No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Influence of reading habits on line bisection
Abstract
The effect of scanning direction on perception of space is studied with a visuo-motor bisection task, among 120 normal dextrals with opposite reading habits (60 French subjects, 60 Israeli subjects). Bisection is found to depend upon subject's reading habits. Israeli bisected the line to the right of the objective centre, while French subjects placed their subjective middle to the left of the objective one. Results are discussed with respect to hemispheric activation theories, directional hypotheses and the neglect syndrome.
... Other proposed factors include scanning habits, which stem from the reading direction of participants; these are thought to govern scanning strategies used during the task and as the final result of perceptual asymmetries (Manning et al., 1990;Abed, 1991). In support of this, previous studies have found consistent leftward bias in native left to right readers and central or rightward bias in right to left readers in various visuospatial tasks (Abed, 1991;Morikawa and McBeath, 1992;Fagard and Dahmen, 2003;Heath et al., 2005;Chokron et al., 2009;Friedrich and Elias, 2014), including those of line bisection (Chokron and Imbert, 1993;Chokron and De Agostini, 1995;Chokron et al., 1997). ...
... Perhaps among the most important factors in line bisection outcomes is native reading habits. A study conducted on 120 normal right-handed Israeli and French subjects (Chokron and Imbert, 1993) revealed that Israeli subjects bisected the line to the right of the center, whereas French subjects bisected the line to the left of the center. This demonstrates that reading habits' may influence bisection, with a rightward bisection for rightto-left readers and a leftward deviation for left-to-right readers. ...
... This finding resembles those described in a previous study of native right-to-left readers who did not have a demonstrable pseudoneglect (Friedrich and Elias, 2014) when performing the gray scale task. Rightward deviation has also been seen in older studies, such as in Chokron and Imbert (1993), in which Hebrew and French readers were compared using a line bisection test that displayed a rightward bias in Hebrew readers. We can assume that the lack of pseudoneglect found here and the rightward deviation found in Middle Eastern participants, among other studies mentioned, is likely to be caused by the reading direction of their native language and Middle Eastern and Islamic cultural favoritism to the right. ...
Objectives: Arabs have a right-to-left language and engage in favoring of the right side or limb when implementing daily routine practices. The purpose of this research is to explore the effect this cultural attitude might have on pseudoneglect, by comparing with a southeast Asian sample that has a left-to-right language structure.
Methods: Participants were from two separate ethnic groups (Arabs and Filipinos), residing in Saudi Arabia, healthy individals 18 years and above were allowed to volunteer in the study. The participants were recruited at King Saud University Medical City and the general community by both convenience and snowball sampling. Social demographic information such as gender, age, years of education, dominant hand, was also documented. The line bisection task (LBT) contained 36 randomly assorted lines of three different lengths placed at five different locations on a white sheet. The percent deviation score (PDS) was used to quantify pseudo-neglect. Tests of statistical significance including t -tests and mixed-effects regression were performed to determine if differences existed among different demographic variables or among line properties, respectively.
Results: A total of 256 were enrolled (Arabs 52.3%). The overall PDS mean and standard deviation (SD) was −0.64 (2.87), p = 0.0004, which shows a significant leftward deviation in the entire cohort. PDS was −1.26 (2.68) in Filipinos, and −0.08 (2.94) in Arabs. The difference was statically significant ( p < 0.0001). Mixed effects model showed positive changes in the PDS value as the length of the line increased ( p < 0.0001) and as the line was more rightward placed ( p < 0.0001). However, Filipino participants would still exhibit negative changes in the PDS value in comparison to Arabs ( p < 0.0001); There were no significant associations between PDS and other factors such as age, years of education and gender.
Conclusion: Differences found here between two distinct ethnic groups support the hypothesis that certain cultural aspects such as language direction and other cultural practices influence direction and degree of pseudo-neglect.
... Studies involving participants with right-to-left reading habits, however, yield results that conflict a pure lateralisation account of spatial asymmetries. Instead of showing the characteristic leftward bias of left-to-right readers, right-to-left readers demonstrate no or a slight rightward asymmetry in perceptual tasks such as line bisection (Chokron & Imbert, 1993;Rinaldi, Di Luca, Henik, & Girelli, 2014), face judgments (Vaid & Singh, 1989), and aesthetic preference judgments (Friedrich & Elias, 2016;Nachson, Argaman, & Luria, 1999). These findings have led to suggestions that participants' habitual script direction is a key factor underlying observed spatial biases (Kazandjian & Chokron, 2008;Maass & Russo, 2003; but see Nicholls & Roberts, 2002, for conflicting findings). ...
... While habitual reading direction is known to influence visuospatial biases (Chokron & Imbert, 1993;Maass et al., 2014), it is poorly understood how immediate prior experiences shape perceptual asymmetries. Studies on how people conceptualise abstract concepts suggest that the bias might be highly malleable. ...
... The current study tests the influence of a mirror-reading manipulation on perceptual asymmetry within two groups with opposite long-term reading direction habits. Demonstrating a highly flexible and adaptive attentional system will have important implications for current theories of spatial biases, which do not currently consider the influence of recent experience (Bowers & Heilman, 1980;Chokron & Imbert, 1993;Kazandjian & Chokron, 2008;Reuter-Lorenz et al., 1990). ...
An accurate perception of the space surrounding us is central for effective and safe everyday functioning. Understanding the factors influencing spatial perception is therefore vital. Here, we first confirm previous reports that our cultural reading habits shape the perception of space. Twenty-four left-to-right readers (tested in Australia) and 23 right-to-left readers (tested in Israel) over-attend to information presented on the left and right side of space, respectively. We then show that this cultural bias is highly malleable. By employing a simple mirror-reading task prior to the spatial judgments, we demonstrate that the supposed cultural bias can be easily overridden. These findings question hardwired, lateralisation models of spatial-attentional biases and highlight the need for a dynamic model that takes into account hemispheric lateralisation, cultural habits and situational context.
... Indeed, many lateralized biases have been shown to be influenced by an individual's habitual reading direction: left-to-right readers have a leftward bias in tasks such as line bisection (Rinaldi, et al., 2014), number line processing (Shaki, Fischer, & Petrusic, 2009), and the light source bias (Andrews et al., 2013). Moreover, habitual reading direction alters typically leftward spatial biases in a number of non-linguistic tasks, generating rightward biases in right-to-left readers (e.g., Chokron & De Agostini, 2000;Chokron & Imbert, 1993). However, if the development of the leftward bias does not depend upon visual experience such as scanning habits, changes in the assumed light source direction should not be related to reading experience. ...
... A range of lateralized biases, including the light source direction, are reliably affected by reading direction (Andrews et al., 2013;Chokron & Imbert, 1993;Friedrich & Elias, 2014;Rinaldi et al., 2014;Smith et al., 2015) suggesting that they are influenced by scanning habits. We measured the relationship between scanning habits (e.g., reading proficiency and the tendency to start cancellation on the left) and the assumed light source direction. ...
The light-from-above prior enables observers to infer an object’s three-dimensional shape-from-shading information. Young, Western adults implicitly assume the light source is placed not only above, but also to the left of, the observer. Previous evidence reached conflicting conclusions regarding the development of the assumed light source direction. In the present study, we measured the light source prior cross-sectionally in children aged 5–11 years, using an explicit shape judgement task. The light-from-above prior, and the left bias, were present as soon as children became sensitive to shading information, regardless of their age. Global processing preference was not related to the ability to perform the task. Similarly, scanning habits, as measured by reading proficiency and starting position in a cancellation task, were not related to the magnitude of the left bias. Children’s ability to report shape-from-shading judgements increased with age, but age did not affect the direction of light priors. Thus, we concluded that the development of the light-from-above prior and leftward bias do not require an extended maturation period, but rather the direction of the light-source priors may be developmentally stable once measurable.
... Habits such as reading have a strong influence on the cognitive system and can introduce spatial biases at both the perceptual and representational levels of a wide range of stimuli. Specifically, biases towards the left have been found in readers of French origin [32] and towards the right in readers of Hebrew [33]. This might be related to attentional issues, but different strategies might also be expected in a participant profile. ...
... The patterns between the two suggested groups showed differences between latencies or response times, so a more conservative pattern will be found for one of the profiles. From a qualitative approach, these results could support sensitivity to oblique information in the near horizontal range or biases [48,49] or preferences towards one of the orientations [32,33]. ...
Face recognition is a crucial subject for public health, as socialization is one of the main characteristics for full citizenship. However, good recognizers would be distinguished, not only by the number of faces they discriminate but also by the number of rejected stimuli as unfamiliar. When it comes to face recognition, it is important to remember that position, to some extent, would not entail a high cognitive cost, unlike other processes in similar areas of the brain. The aim of this paper was to examine participant’s recognition profiles according to face position. For this reason, a recognition task was carried out by employing the Karolinska Directed Emotional Faces. Reaction times and accuracy were employed as dependent variables and a cluster analysis was carried out. A total of two profiles were identified in participants’ performance, which differ in position in terms of reaction times but not accuracy. The results can be described as follows: first, it is possible to identify performance profiles in visual recognition of faces that differ in position in terms of reaction times, not accuracy; secondly, results suggest a bias towards the left. At the applied level, this could be of interest with a view to conducting training programs in face recognition.
... Letter strings and sentences were therefore bisected more leftward compared to lines. The smaller rightward deviation shown by USN patients with readable sentences might be indicative of a less asymmetrical spatial exploration, mediated by the linguistic features of the stimuli, and is in line with the left-to-right Italian reading habits (Chokron and Imbert, 1993;Girelli et al., 2017). The readability of the stimulus may be a factor to explain the ortho-phonological effect found in sentence bisection, with a reduction of the rightward deviation for sentential material compared to letter strings and lines in USN patients, and a leftward bias for control participants (see Veronelli et al., 2014a, for details). ...
... Healthy participants exhibited a leftward deviation with all stimuli, namely different types of sentences, letter strings and lines, showing larger leftward biases with orthographic readable sentences, as compared to unreadable letter strings. These findings confirm previous evidence (Fischer, 1996;Veronelli et al., 2014a) that the presence of readable material may induce a more pronounced leftward shift of attention, possibly through an activation of left hemisphere-based linguistic processes, that orient more leftward, toward the beginning of the to-be-bisected letter string, readable in Italian from left to right (see Chokron et al., 1998;Chokron and Imbert, 1993). Furthermore, the leftward biases in bisection for lines and words, that mark the performance of neurologically unimpaired adults, develop with different directional patterns between three and eight years of age, suggesting that different factors, including visuo-spatial attention and linguistic processes, may be involved . ...
... Specific forms of visuospatial asymmetry have been documented, notably with regard to the apparent nearness (Adair & Bartley, 1958) or center (Bowers & Heilman, 1980) of portrayed elements. However, these results do not necessarily imply an asymmetry of the pictorial space, nor do they agree on the contribution of the reading/writing system (Chokron & Imbert, 1993;Ishii et al., 2011). ...
... Finally, our finding that the Syrian population has an opposite asymmetry strongly suggests a cultural origin linked to the directionality of the reading/writing system. Writing/reading habits had already been shown to affect our esthetic preferences for pictures (Chokron & De Agostini 2000;Ishii et al. 2011;Nachson et al., 1999;Smith & Elias 2013), but their role in the perceptual domain remained controverted (Chokron & Imbert, 1993;Ishii et al., 2011). Contrary to those previous studies, our approach addresses pictorial space through its scaling effect on the perceived sizes (Boring, 1964;Gibson, 1950). ...
Art experts have argued that the mirror reversal of pictorial artworks produces an alteration of their spatial content. However, this putative asymmetry of the pictorial space remains to be empirically proved and causally explained. Here, we address these issues with the “corridor illusion,” a size illusion triggered by the pictorial space of a receding corridor. We show that mirror-reversed corridors—receding respectively leftward and rightward—induce markedly different illusion strengths and thus convey distinct pictorial spaces. Remarkably, the illusion is stronger with the rightward corridor among native left-to-right readers (French participants, n = 40 males) but conversely stronger with the leftward corridor among native right-to-left readers (Syrian participants, n = 40 males). Together, these results demonstrate an asymmetry of the pictorial space and point to our reading/writing habits as a major cause of this phenomenon.
... In conjunction with hemispheric asymmetries, pseudoneglect is believed to result from, or is conversely attenuated by, native reading direction (NRD). Neurotypical participants with a right-to-left (RTL) NRD display an opposite rightward bias on the line bisection task (Chokron & Imbert, 1993) and attenuated leftward lighting preferences (Smith & Elias, 2013). We present a spatial location task and an aesthetic task executed in a functionally similar way by both left-to-right (LTR) and RTL reading participants. ...
... Just as leftward aesthetic preferences and pseudoneglect may be related, RTL NRD may attenuate leftward aesthetic preference in the same way seen in pseudoneglect (Chokron & Imbert, 1993;Fagard & Dahmen, 2003;Rinaldi et al., 2014). In one of the clearest examples of the influence of NRD, Rinaldi et al. report leftward biases among LTR monolinguals, rightward biases by RTL monolinguals, and no spatial biases by bilinguals on the line bisection and star cancellation tasks. ...
People exhibit consistent leftward spatial biases across a variety of tasks. However, individuals with a native reading direction other than left-to-right (LTR) show an attenuation of the leftward bias. The current study used procedurally similar tasks to examine spatial ability and aesthetic preferences in LTR and right-to-left (RTL) groups. In the spatial task participants viewed a centred rectangle partially occluded by an overlapping circle and estimated the centre of the circle with a single mouse click. In the aesthetic task participants used the mouse to control a “virtual flashlight” to light images of abstract paintings in the most aesthetically pleasing way. Contrary to predictions, smaller errors were made for circles on the right and estimations were progressively less accurate as circle size increased in the spatial task. On the aesthetic task, light placements of LTR participants were biased to the left and significantly different from the slightly rightward placements of RTL participants. As predicted, when completing the aesthetics task amounts of time scanning left or right visual space were different between groups. Findings support the theory that directional scanning biases attenuate leftward lateral biases and further, the nature of the visuospatial task may vary the strength of lateral bias.
... Future directions examining spatial lateral biases in driving may also include determining if individual differences like age, sex, handedness (Jewell & McCourt, 2000) and native reading direction (e.g., right-to-left readers; Chokron & Imbert, 1993) that have been found to influence lateral spatial attention also effect driving. Further, investigation into the lateral allocation of overt visual attention relating to driving performance has yet to occur, even though several studies have measured eye movements when driving (e.g., Benedetto et al., 2013;Robertshaw & Wilkie, 2008;Zheng et al., 2020). ...
Whereas a rightward bump is more likely than a leftward bump when walking through a doorway, investigations into potential similar asymmetries for drivers are limited. The research presented here aims to determine the influence of innate lateral spatial biases when driving. Data from the Strategic Highway Research Program Naturalistic Driving Study (SHRP 2 NDS) and a driving simulation were used to address our research questions. Data points from SHRP 2 were aggregated within relevant variables (e.g., left/right obstacles). In the simulation, participants drove in ways that were consistent with their everyday driving in urban and rural environments. Collision frequency, collision severity and average lateral lane position were analyzed with rightward biases throughout both analyzes. SHRP 2 data indicated greater likelihoods of collisions when vehicles crossed the right line/edge of the road and when making a right turn. There were more collisions with obstacles on the right side, which were also more severe, and greater rightward lane deviations in the driving simulation, contrasted with more severe collisions on the left side in SHRP 2 data, possibly because of the presence of traffic. These findings suggest that previously observed rightward biases in distant space when walking are also present when driving.
... It is possible that the sources of the leftward and upward biases differ from the central bias and may be potentially related to the temporal distribution of spatial attention and scanning patterns (47,60,61). As suggested by prior work (43,44), a potential cause of the leftward bias is the reading habits, since most of our participants read from left to right and up to down (62,63). Thus, although speculative, the temporal rise and fall of these biases observed in Experiment 4 ( Figure 9) may reflect initial 'hard-wired' transitory biases in spatial processing, followed by inhibition and subsequent re-engagement with similar biases (64-66). ...
The human brain can rapidly represent sets of similar stimuli by their ensemble summary statistics, like the average orientation or size. Classic models assume that ensemble statistics are computed by integrating all elements with equal weight. Challenging this view, here we show that ensemble statistics are estimated by combining parafoveal and foveal statistics in proportion to their reliability. In a series of experiments, observers reproduced the average orientation of an ensemble of stimuli under varying levels of visual uncertainty. Ensemble statistics were affected by multiple spatial biases. In particular, a strong and persistent bias toward the center of the visual field. This bias, evident in the majority of subjects and in all experiments, scaled with uncertainty: the higher the uncertainty in the ensemble statistics the larger the bias towards the element shown at the fovea. Our findings indicate that ensemble perception cannot be explained by simple uniform pooling. The visual system weights information anisotropically from both the parafovea and the fovea, taking the intrinsic spatial anisotropies of vision into account to compensate for visual uncertainty.
... They proposed to investigate the influence of reading direction on regulating the functional organization of the human brain as well as related neurocognitive processes [19]. Reading direction has been found to influence many cognitive functions, such as directional differences in facial expression perception [20], aesthetic preference [21] and utilization of visual space [22]. Especially, visuospatial attention could be modulated by the habitual reading direction. ...
Cognitive processes can influence the characteristics of saccadic eye movements. Reading habits, including habitual reading direction, also affect cognitive and visuospatial processes, favouring attention to the side where reading begins. Few studies have investigated the effect of habitual reading direction on saccade directionality of low-cognitive-demand stimuli (such as dots). The current study examined horizontal prosaccade, antisaccade, and self-paced saccade in subjects with two primary habitual reading directions. We hypothesised that saccades responding to the stimuli in subject's habitual reading direction would show a longer prosaccade latency and lower antisaccade error rate (errors being a reflexive glance to a sudden-appearing target, rather than a saccade away from it). Sixteen young Chinese participants with primary habitual reading direction from left to right and sixteen young Arabic and Persian participants with primary habitual reading direction from right to left were recruited. All subjects spoke/read English as their second language. Subjects needed to look towards a 5°/10° target in the prosaccade task or look towards the mirror image location of the target in the antisaccade task and look between two 10° targets in the self-paced saccade task. Only Arabic and Persian participants showed a shorter and directional prosaccade latency towards 5° stimuli against their habitual reading direction. No significant effect of reading direction on antisaccade latency towards the correct directions was found. Chinese readers were found to generate significantly shorter prosaccade latencies and higher antisaccade directional errors compared with Arabic and Persian readers for stimuli appearing at their habitual reading side. The present pilot study provides insights into the effect of reading habits on saccadic eye movements of low-cognitive-demand stimuli and offers a platform for future studies to investigate the relationship between reading habits and eye movement behaviours.
... Importantly, in Experiment 2 of Fantoni et al. 18 the spatial congruity anisotropy was found to be particularly evident when emotional pairs were displayed tachistoscopically rather than until participant response. The reason for such a difference remained unsolved, although authors hypothesized that such a difference resulted from an endogenous factor of attention modulating PAF [41][42][43][44][45][46][47][48][49][50] . This endogenous factor of attention might be driven by the scanning habit, that prioritizes stimuli either on the left or on the right visual hemifield depending on the temporal phase of the scanning of the visual scene. ...
Humans are predisposed to attend to emotions conveyed by facial expressions. However, compulsory attraction to emotions gets challenging when multiple emotional stimuli compete for attention, as in the emotion comparison task. In this task, participants are asked to choose which of two simultaneously presented faces displays the most positive (happiest) or negative (angriest) emotion. Participants usually respond faster to the face displaying the most intense emotion. This effect is stronger for face pairs that contain globally positive rather than negative emotional faces. Both effects are consistent with an attentional capture phenomenon driven by the perceptual salience of facial expressions. In the present experiment, we studied the temporal dynamics of attentional capture in the emotion comparison task by tracking participants’ eye movements using gaze-contingent displays and responses. Our results show that, on the first fixation, participants were more accurate and dwelled longer on the left target face when it displayed the most intense emotion within the pair. On the second fixation, the pattern was reversed, with higher accuracy and longer gaze time on the right target face. Overall, our pattern of gazing behavior indicates that the typical results observed in the emotion comparison task arise from the optimal combination over time of two low-level attentional factors: the perceptual salience of emotional stimuli and the scanning habit of participants.
... Some studies have found that reading habits and scanning direction could affect pseudo-neglect. Chokron and Imbert (1993) discussed the pseudo-neglect of French and Israeli participants and found that the Israeli participants bisected the line to the right of the objective center, while the French participants placed their subjective middle to the left of the objective. Friedrich and Elias (2014) reported that scanning habits affected spatial biases in attention with a greyscale task. ...
Previous studies have demonstrated that spatial location impacts temporal order perception, and that the effect of spatial location on temporal order perception varies across cultures. English and Spanish speakers can perceive left-side stimuli occur earlier than right-side stimuli, while native Hebrew speakers do not express this characteristic. Likewise, only a few studies have investigated the effect of spatial location on temporal order perception in Chinese culture, which would be the main aim of this research. In Experiments 1–3, a temporal order judgment (TOJ) task, simultaneity judgment (SJ) task, and TOJ-SJ dual-task were used to test the effect of spatial location on temporal order perception. On the horizontal axis, the effect of spatial location on temporal order perception was observed only in the TOJ task, with Mandarin speakers perceiving left-side stimuli occur earlier than right-side stimuli. On the vertical axis, Mandarin speakers consistently perceived the top-side stimuli occur earlier than the bottom-side stimuli in every task. In Experiment 4, an ‘orthogonal’ (location-unrelated) TOJ task was used, where the participants were required to judge the color order that appeared. We also observed the effect of spatial location (top or left) on temporal order perception in this experiment. The results indicated that the effects of spatial location on temporal order perception were robust in both horizontal and vertical directions.
... Directional spatial biases in this task were attributed to right hemisphere specialization for visuospatial processing and thus a greater allocation of attention to the left side of visual space (Bryden, 1982;Kinsbourne, 1970). However, the typical pattern of leftward displacement was not observed when the line bisection task was conducted with right-to-left readers (Chokron & Imbert, 1993). Thus, spatial biases need not always-or only-reflect cerebral laterality effects but could more parsimoniously be interpreted as script directionality effects-that is, effects arising from (left to right) directional reading and writing habits (Vaid, 2011). ...
Becoming literate has been argued to have a range of social, economic and psychological effects. Less examined is the extent to which repercussions of becoming literate may vary as a function of writing system variation. A salient way in which writing systems differ is in their directionality. Recent studies have claimed that directional biases in a variety of spatial domains are attributable to reading and writing direction. This claim is the focus of the present paper, which considers the scope and possible mechanisms underlying script directionality effects in spatial cognition, with particular attention to domains with real-world relevance. Three questions are addressed: (1) What are possible mediating and moderator variables relevant to script directionality effects in spatial cognition? (2) Does script directionality exert a fixed or a malleable effect? and (3) How can script directionality effects be appropriately tested? After discussing these questions in the context of specific studies, we highlight general methodological issues in this literature and provide recommendations for the design of future research.
... To our knowledge, this is the first investigation of the feasibility of doing so, and of the data quality that can be expected. The vast majority of bisection data in the literature has come from left-to-right reading cultures, and the leftward bias of pseudoneglect may be reduced or even reversed in right-to-left readers (Chokron & De Agostini, 1995;Chokron & Imbert, 1993;Muayqil et al., 2021;Rinaldi, Di Luca, Henik, & Girelli, 2014; but see Nicholls & Roberts, 2002, for a contrary result). To test the validity of our online tasks for the measurement of pseudoneglect, we will concentrate on leftto-right (dextrad) readers, for whom we can most confidently expect a leftward bias. ...
This study assessed pseudoneglect using line bisection and perceptual landmark tasks in two matched online sessions. Line bisection bias was characterized by the traditional measure of Directional Bisection Error (DBE), and by Endpoint Weightings Bias (EWB), derived from an "endpoint weightings" analysis, made possible by the independent manipulation of left and right endpoints. EWB is proposed to index the relative attentional allocation to the two ends of the line. The expected leftward bias (pseudoneglect) was found, with larger effect sizes for EWB (d = -0.34 in both sessions) than for DBE (-0.22 in Session 1 and -0.14 in Session 2). Although EWB was slightly less reliable than DBE, it was more sensitive to pseudoneglect, and the endpoint weightings method has further advantages, including the option of an additional measure of non-lateralized attention. A substantial proportion of participants had difficulty following the instructions for the landmark task, which highlights the need for clear instructions and performance checks for this task. This study shows that line bisection can be used to measure pseudoneglect online, and provides grounds to suggest that the task should routinely include the independent manipulation of left and right endpoints, so that an endpoint weightings analysis can be performed.
... An imbalance of hemispheric activity is hypothesized to be the neural underpinning of pseudoneglect, directing attention contralateral to the most activated hemisphere, with a predominant role of the right hemisphere in visuospatial processing (Benwell, Harvey, & Thut, 2014;Bultitude & Aimola Davies, 2006;de Schotten et al., 2005;Kinsbourne, 1970). The tendency toward underestimating one side relative to the other is reported to be relatively stable intra-individually (e.g., Learmonth, Gallagher, Gibson, Thut, & Harvey, 2015, but differs between individuals across age and other demographic variables such as reading habits (Chokron & Imbert, 1993;Friedrich, Hunter, & Elias, 2018;Jewell & McCourt, 2000;Learmonth & Papadatou-Pastou, 2021;M€ arker, Learmonth, Thut, & Harvey, 2019). Besides the manual line bisection task, other paper-andpencil based tasks, like the greyscales task (Mattingley et al., 2004), have shown to be sensitive to pseudoneglect. ...
Spatial attention is generally slightly biased leftward (“pseudoneglect”), a phenomenon typically assessed with paper-and-pencil tasks, limited by the requirement of explicit responses and the inability to assess on a sub-second timescale. Pseudoneglect is often stable within experiments, but differs vastly between investigations and is sometimes directed to the left, sometimes to the right. To date, no exhaustive explanation to this phenomenon has been provided. Here, we objectively assessed lateralized attention over time, exploiting the phenomenon that changes in the pupil reflect the allocation of attention in space. Pupil sizes of 41 healthy participants fixating the center were influenced stronger by the differential background luminance of the left side compared to the right side of the visual display. These differences were mainly driven by visual information in the periphery. Differences in pupil sizes positively related with greyscales scores. Time-based analyses within trials show strongest effects early on. With increasing trial number (not time), the initial leftward bias shifted central in pupillometry-based and greyscales measures. This suggests that the orienting response determines the degree of attention bias. In our amplification hypothesis we pose that the quality of pseudoneglect (i.e. the direction) is determined by higher order factors such as hemispheric imbalances, whereas the quantity (i.e. the degree) is determined by the orienting network. This account might explain numerous - previously thought opposing - findings. We here show how pupil light responses reveal pseudoneglect, in a next step, this might allow clinical diagnosis of hemispatial neglect.
... Ishii, Okubo, Nicholls, & Imai, 2011;Kazandjian, Cavézian, Zivotofsky, & Chokron, 2010;Tversky, Kugelmass, & Winter, 1991;Vaid & Singh, 1989). Chokron & Imbert (1993) compared French and Israeli subjects in a line bisection task and found that French-speakers, that is LR readers, tended to place the subjective centre of a line to the left of its actual centre whereas Hebrew-speakers, RL readers, showed the opposite tendency. English speakers seem to exhibit strong LR preferences. ...
Directional preferences in moving images are primarily theorized as deriving from 'cultural' factors, principally the dominant language's reading/writing direction. This study examines the origins of this notion and positions it within recent analytical thinking. In order to expand the context of analysis it draws in research from neurology and practical knowledge of typical production tools. Two manifestations of directionality-camera panning movements (pans) and soundbite gaze direction-are compared, data is drawn from two countries, Japan and the UK, where directional conventions may differ. Results suggest there is a limited degree of support for the hypothesis that reading/writing direction is linked to directional preferences in television news image creation, but the processes involved may be subconscious rather than conscious and analysts should therefore be wary of attributing semiotic significance to these variations, of 'over-reading' manifestations of directionality in news images.
... This is true even for abstract stimuli that have no intrinsic directionality (Harcum & Friedman, 1963;Nachshon et al., 1977). The leftwards or rightwards bias in visual exploration extends to equivalent biases in line bisection (Chokron & De Agostini, 1995;Chokron & Imbert, 1993), the mental representation of actions (Dobel et al., 2007), the execution of spatially directed movements (such as drawing a circle clockwise or counterclockwise; Fagard & Dahmen, 2003), and aesthetic preference (Chokron & De Agostini, 2000). It biases even relatively low-level mechanisms, such as inhibition of return (Spalek & Hammad, 2005) and the shape of the perceptual span (Paterson et al., 2014). ...
Visuo-spatial reasoning tests, such as Raven’s matrices, Cattell’s culture-fair test, or various subtests of the Wechsler scales, are frequently used to estimate intelligence scores in the context of inter-racial comparisons. This has led to several high-profile works claiming that certain ethnic groups have lower intelligence than others, presumably due to genetic inferiority. This logic is predicated on the assumption that such visuo-spatial tests, because they are non-verbal, must be culture-fair: that their solution process does not significantly draw on factors that vary from one culture to the next. This assumption of culture-fairness is dubious at best and has been questioned by many authors. In this article, I review the substantial body of psychological and ethnographic literature which has demonstrated that the perception, manipulation and conceptualization of visuo-spatial information differs significantly across cultures, in a way that is relevant to intelligence tests. I then outline a model of how these inter-cultural differences can affect seven major steps of the solution process for Raven’s matrices, with a brief discussion of other visuo-spatial reasoning tests. Overall, a number of cultural assumptions appear to be deeply ingrained in all visuo-spatial reasoning tests, to the extent that it disqualifies the view of such tests as intrinsically culture-fair and makes it impossible to draw clear-cut conclusions from average score differences between ethnic groups.
... Furthermore, evidence of a leftward bias in preverbal infants would challenge the notion that cultural experience drives attentional asymmetries. Although there is ample evidence that reading and writing habits modulate directional biases (Chokron & Imbert, 1993), this evidence speaks for the plastic nature of such biases (West & McCrink, 2021) but cannot rule out their origins and early development (Rinaldi, Di Luca, Henik, & Girelli, 2014). Finally, the finding of a leftward bias in visuospatial attention would prove to be critical to the claim that attentional asymmetries, particularly in oculomotor scanning behavior, would act in conjunction with the early emerging right hemispheric dominance in the control of visuospatial attention to promote visual learning in the first year of life (Bulf, de Hevia, Gariboldi, & Macchi Cassia, 2017). ...
Adults present a large number of asymmetries in visuospatial behavior that are known to be supported by functional brain lateralization. Although there is evidence of lateralization for motor behavior and language processing in infancy, no study has explored visuospatial attention biases in the early stages of development. In this study, we tested for the presence of a leftward visuo-spatial bias (i.e., pseudoneglect) in 4- and 5-month-old infants using an adapted version of the line bisection task. Infants were trained to identify the center of a horizontal line (Experiment 1)while their eye gazes were monitored using a remote eye-tracking procedure to measure their potential gazing error. Infants exhibited a robust pseudoneglect, gazing leftward with respect to the veridical midpoint of the horizontal line. To investigate whether infants’ pseudoneglect generalizes to any given object or is dependent on the horizontal dimension, in Experiment 2 we assessed infants’ gaze deployment in vertically oriented lines. No leftward bias was found, suggesting that early visuospatial attention biases in infancy are constrained by the orientation of the visual plane in which the information is organized.The interplay between biological and cultural factors that might contribute to the early establishment of the observed leftward bias in the allocation of visuospatial attention is discussed.
... An important factor which researchers should be aware of is that maybe this tendency could be due to the reading habit and thus to cultural backgrounds. For example, Chokron and Imbert [34] found that Israeli subjects bisected the line to the right of the objective center, while French subjects placed their subjective middle to the left of the objective one, according to the direction of the reading preferences (left-to-right for French and right-to left for Israeli). Similar results [35] came out comparing monolingual and bilingual readers: according to their mother-tongue reading habits, results showed that monolingual readers deviated leftward (for left-to-right), or rightward (for right-to-left); bilingual readers show no significant bias. ...
Spatial abilities allow humans to perceive and act in the world around them. Combining technology with a wide used neuropsychological test, the E-Baking Tray Task have proved to be very versatile and useful. Here we examine its properties and potentialities, trying to propose new challenges in visuospatial cognition. Firstly, we address to actual algorithms of data analysis and propose new ones. Then we propose several new variables that could be inspected related to spatial exploration measured with this new device: verticality, stress, emotions, explored areas in peri-personal space and so on.
... The cause of this leftward bias remains unresolved but could be due to hemispheric asymmetries in visuospatial attention (Bowers & Heilman, 1980;Jewell & McCourt, 2000). An alternative explanation is that the leftward bias is due to reading direction habits (Afsari et al., 2016;Chokron & Imbert, 1993). As we did not assess the initial spatial bias in a group of neurologically healthy controls, we cannot conclude whether the initial bias shifted toward the left in patients with left-sided brain damage and toward the right in patients with right-sided brain damage, or whether a shift was present for one of the groups only. ...
Introduction:
Impairments in visual search are a common symptom in visuospatial neglect (VSN). The severity of the lateralized attention bias in visual search tasks can vary depending on the number of distractors: the more distractors, the more targets are missed. However, little is known about how the number of targets affect search performance in VSN. The aim of the current study was to examine the effect of the number of targets on hit rate in VSN.
Methods:
We included 23 stroke patients with right-brain damage and VSN, 55 with right-brain damage without VSN, and 49 with left-brain damage without VSN, all admitted for inpatient rehabilitation. In a visual search task, patients had to find and tap targets, presented along with non-targets. The location and number of targets varied from trial to trial, allowing the evaluation of the effects of number and location of targets on hit rate.
Results:
VSN patients detected a lower percentage of targets when more targets were present. For patients with right-brain damage without VSN, adding targets only reduced the hit rate of the most contralesional target. No effect of number of targets on hit rate was seen in patients with left-brain damage. Additionally, VSN patients found less contralesional targets than ipsilesional targets, made more delayed revisits, and had an initial rightward bias when compared to the other groups. There were no differences in search time, search consistency, or immediate revisits between groups. There was a moderate positive relation between the hit rate asymmetry score in our search task and conventional paper-and-pencil VSN tasks, and neglect behavior in daily life.
Conclusions:
In VSN patients, a higher number of targets reduces the hit rate. The reduced hit rate in visual search evoked by additional targets should be taken into account when assessing visual search in VSN.
... This explanation is backed up by the observation that bisection errors shift to the right of the veridical center when scanning direction is manipulated to start from the right-end side of the line (Jewell & McCourt, 2000). Even more compelling evidence is that right-to-left readers demonstrate rightward bisection deviations during free-viewing conditions (Chokron and De Agostini, 1995;Chokron and Imbert, 1993;Muayqil et al., 2019;Nachshon, 1985;Rinaldi et al., 2014; but for a conflicting report, see Nicholls and Roberts, 2002). ...
... Critically, evidence for a cultural shaping of pseudoneglect-like biases is also not lacking. That is, reading habits have been found to influence line bisection tasks with readers of left-to-right oriented languages showing a leftward bias and readers of right-to-left oriented languages displaying an opposite, rightward bias [88][89][90]. These cross-cultural differences indicate that visuospatial asymmetries would reflect the tendency to scan information in the direction in which one reads. ...
The human cerebral cortex is asymmetrically organized with hemispheric lateralization pervading nearly all neural systems of the brain. Whether the lack of normal visual development affects hemispheric specialization subserving the deployment of visuospatial attention asymmetries is controversial. In principle, indeed, the lack of early visual experience may affect the lateralization of spatial functions, and the blind may rely on a different sensory input compared to the sighted. In this review article, we thus present a current state-of-the-art synthesis of empirical evidence concerning the effects of visual deprivation on the lateralization of various spatial processes (i.e., including line bisection, mirror symmetry, and localization tasks). Overall, the evidence reviewed indicates that spatial processes are supported by a right hemispheric network in the blind, hence, analogously to the sighted. Such a right-hemisphere dominance, however, seems more accentuated in the blind as compared to the sighted as indexed by the greater leftward bias shown in different spatial tasks. This is possibly the result of the more pronounced involvement of the right parietal cortex during spatial tasks in blind individuals compared to the sighted, as well as of the additional recruitment of the right occipital cortex, which would reflect the cross-modal plastic phenomena that largely characterize the blind brain.
... The opposite preferential representation of agency (i.e., evolving from right-to-left) has been largely reported in leftward flowing languages in distinct attentional and cognitive processes. For instance, line bisection (Chokron and Imbert, 1993), directionality in drawing side view objects (Kebbe and Vinter, 2012), time and number line representation (Dehaene et al., 1993;Ouellet et al., 2010), thematic role drawing tasks (Maass and Russo, 2003), are all heterogeneous but converging examples of how leftward speaking populations preferentially conceived movement as unfolding from rightto-left. However, most reported reversals are considerably weaker in cultures where writing is leftward (Román et al., 2013), likely due to their frequent exposure to westernized spatial layouts whereas exposure to leftward cultures in the West is less frequent. ...
We examined whether reading and writing habits known to drive agency perception also shape the attribution of other agency-related traits, particularly for faces oriented congruently with script direction (i.e., left-to-right). Participants rated front-oriented, left-oriented and right-oriented faces on 14 dimensions. These ratings were first reduced to two dimensions, which were further confirmed with a new sample: power and social-warmth. Both dimensions were systematically affected by head orientation. Right-oriented faces generated a stronger endorsement of the power dimension (e.g., agency, dominance), and, to a lesser extent, of the social-warmth dimension, relative to the left and frontal-oriented faces. A further interaction between the head orientation of the faces and their gender revealed that front-facing females, relative to front-facing males, were attributed higher social-warmth scores, or communal traits (e.g., valence, warmth). These results carry implications for the representation of people in space particularly in marketing and political contexts. Face stimuli and respective norming data are available at www.osf.io/v5jpd.
... The directionality of our writing system also influences the way we scan (nonlinguistic) visual information (e.g., a picture array), an effect that is absent in illiterates (Padakannaya et al. 2002). More generally, script directionality influences visuospatial attention (e.g., Chokron and Imbert 1993;Rinaldi et al. 2014) and the spatial representation of actions and scenes, when subjects have to draw or arrange toy figures in response to spoken descriptions (Dobel et al. 2014;Roman et al. 2013). It also induces spatial biases at abstract representational levels. ...
The present paper, which is the first of two twin opinion papers, offers a theoretical approach of literacy and critical literacy in relation to language, thought, and reasoning. Literacy acquisition and practice proceed through two stages, which partially overlap in terms of processing abilities: the first is achieved when the learner becomes a skilled reader and writer, characterized by automatic word processing; the second, when reading comprehension and written production become expert instruments in the communication of progressively more abstract and sophisticated, but always linguistically-mediated, knowledge and ideas. The destiny of literacy, depending on educational and social factors, is thus to be to fused with language, thought and reasoning. Oral language becomes literate language; and our cognitive activity becomes—as indicated in the title—“seeing thought”, which paves the way, we will argue, for reasoning skills. Making of literacy an epistemic and social tool of our own collective history requires a critical stance that raises itself and ourselves to a stage called critical literacy. In this paper we focus on some of the favorable and unfavorable factors influencing this achievement. The main challenge is to bring literate cognition up to the capacity of choosing between accept and verify, between belief and disbelief, by weighting evidence and reasoning, by arguing and debunking errors and falsities. Accordingly, our objective is essentially to narrate how literacy gives birth to critical literacy and explain why, at the end of this process, critical literacy becomes hard to distinguish from thinking and reasoning.
... Yet, despite the fact that this neurobiological interpretation can account for most of the findings across Western populations, its strength and alleged universality have been firmly challenged during the past two decades by increasing cross-cultural evidence (for a review, see Chokron, Kazandjian, & De Agostini, 2011). In a series of studies involving adults with opposite reading habits, reading direction has been shown to affect visuospatial performance in line bisection paradigms (Chokron, Bernard, & Imbert, 1997;Chokron & Imbert, 1993;Kazandjian, Cavézian, Zivotofsky, & Chokron, 2010; but see Nicholls & Roberts, 2002). For instance, whereas French participants (reading from left to right) typically display the expected leftward bias, Israeli participants (reading from right to left) generally show a reduced or even opposite tendency, that is, a rightward bias (see Chokron et al., 2011). ...
A tendency to over-attend the left side of the space (i.e., pseudoneglect) has been repeatedly reported in Western adult populations and is supposed to reflect a right hemisphere dominance in the control of visuospatial attention. This neurobiological hypothesis has been partially challenged by growing evidence showing that pseudoneglect is profoundly triggered by cultural practices such as reading and writing habits. Accordingly, more recent theoretical accounts suggest a strict coupling between nature and nurture dimensions at the origins of such bias. To further explore this possibility, here we first administered a digitized cancellation task to right-handed Western children before and after literacy acquisition. Results showed an incremental leftward shift of attention in the cancellation of the first target and an increasing preference for a left-to-right visual search from preschoolers to second graders. Yet, despite these differences, the overall distribution of visuospatial attention was biased to the left in both groups. To explore the role of handedness in visuospatial asymmetries, we also tested a group of left-handed second graders. Results showed an impact of handedness on visuospatial performance, with an accentuated rightward-oriented visual search for left-handed children, although the overall distribution of attention was again biased to the left hemispace. Taken together, these findings do not provide support to a pure neurobiological view of visuospatial biases. Rather, our study indicates that the control of visuospatial attention is mediated by a dynamic interplay among biological (i.e., right hemisphere dominance), biomechanical (i.e., hand dominance), and cultural (i.e., reading habits) factors.
... Regarding the sex-related effects, some researchers reported that men showed greater deviation to the left than women (Roig & Cicero, 1994), others reported that men transected the lines further to the right (Jewell & McCourt, 2000;Wolfe, 1923). Many of the researchers failed to find significant effects of sex on line bisection performance (Asenova, 2014;Bradshaw, Nettleton, Nathan, & Wilson, 1985;Brodie & Pettigrew, 1996;Chokron & Imbert, 1993;Luh, 1995;Scarisbrick, Tweedy, & Kuslansky, 1987;Shuren, Wertman, & Heilman, 1994). ...
Eighty-eight Bulgarian children (range 5 – 7 years old), 40 left handers (18 boys) and 48 right handers (26 boys), completed line-bisection test one time with each hand. In accordance with previous studies the results show that the majority of children demonstrated deviation to the left of the true center with the left hand and to the right with the right hand, suggesting symmetrical neglect. Sex, handedness and their interaction had no main effect on mean percentage deviation scores at the group level, but only sex had a significant impact on the frequency of symmetrical neglect (p < .05), with higher one in girls than in boys.
... The effect of reading/writing direction has also been reported in the direction of drawing vehicles or animals (Vaid, 1995) or human facial profiles (Tosun & Vaid, 2014), and in the placement in space of symmetrical figures (Faghihi et al., 2019). A reading/writing direction effect has also been noted in tasks involving speeded dot production proceeding in different directions (Vaid, 1998), in line length estimation (Singh, Vaid, & Sakhuja, 2000), line bisection (Chokron & Imbert, 1993), figure perception in the orientation of published drawings and pictures (Lee & Oh, 2016), aesthetic judgments of motion trajectories (Friedrich et al., 2014;Maass, Pagani, & Berta, 2007), and even in number representation (for a review, see G€ obel, Shaki, & Fischer, 2011;N uñez, 2011). Directional biases related to reading/writing direction may also be temporarily induced (or reversed) by exposure to mirror-reversed script (Roman, Flumini, Lizano, Escobar, & Santiago, 2015). ...
We examined the performance of right- and left-handed brain-intact adult readers of English or Farsi on a hemi-image generation task in which participants were to imagine and then draw halves of objects using either their dominant or nondominant hand. Which half of the object was drawn was examined in relation to biomechanical, cerebral laterality, and cultural predictors. Findings showed a differential side bias as a function of reading/writing direction and hand used to draw. Specifically, when the dominant hand was used to draw (Experiment 1), English left-handers produced more left hemi-images while Farsi right-handers produced more right hemi-images. Body specificity associated with hand used, however, drove spatial preference when enlisting the nondominant hand (Experiment 2) with English right-handers now showing a significant left hemi-image bias and English left-handers showing a right hemi-image bias. Farsi right-handers using their nondominant hand did not show a significant bias in either direction. Taken together, the findings suggest a joint influence of handedness and reading/writing direction, aligned with an embodiment account of directional spatial biases.
... Indeed, when line bisections were significantly biased, it was systematically towards the left side of lines. Such deviation towards the left side of space has already been documented in neurologically healthy participants, including during line bisection tests ( [49][50][51][52]; for a review see [53,54]). This leftward spatial bias so-called pseudoneglect has been discussed as reflecting attentional asymmetry due to hemispheric dominance in spatial attention control [55] and an involvement of the right cortical hemisphere controlling the allocation of attention towards both the contralateral and ipsilateral hemispaces [56]. ...
Complex Regional Pain Syndrome (CRPS) is characterized by pain, motor and inflammatory symptoms usually affecting one limb. Cognitive difficulties have been reported to affect patients’ ability to represent, perceive and use their affected limb. It is debated whether these difficulties result from deficits in controlling goal-directed movements in space or from a learned strategy to protect the affected limb. In order to dissociate the two hypotheses, patients with upper-limb CRPS were asked to move with their unaffected hand towards visual targets projected at different positions on a horizontal semi-reflexive mirror. By means of a robotic handle placed below the screen, they were asked to move a cursor, to reach and cross lines at their estimated midpoint. In some of the stimulation series, the affected hand was placed below the mirror so that some lines appeared projected onto that hand. Vision of the hands and the robotic handle was preserved or prevented by opening or closing a shutter below the mirror. Lines were displayed on the mirror according to which part of the body was affected (ispi- vs. contralateral) and the actual position of the affected hand (inside vs. outside the workspace). Comparatively to control participants, CRPS patients generally biased their estimation by bisecting the lines towards their left side, irrelative of which part of the body was affected and the position of the affected hand, both in ipsi- and contralateral space, with only a few exceptions. Our results are in line with previous studies having described a visuospatial deficit in CRPS patients and discard the explanation of observed symptoms in terms of learned nonuse strategies, as only the unaffected hand was used to perform the task. It is suggested that CRPS patients can display difficulties to perform tasks requesting visuo-motor coordination, reflecting the complex cortical reorganization occurring in CRPS.
... Bisection performance has been extensively studied also in healthy individuals. Several factors may influence their performance, such as spatial orientation [3,4], learned reading direction [5], presence of contextual stimuli [6][7][8], and the age of the subjects [9]. Some researchers found a tendency of healthy subjects to bisect horizontal lines to the left of the true midpoint [4], others reported considerable interindividual variability in the direction and extent of errors [10,11]. ...
Under visual guidance, healthy subjects usually misbisect radial lines farther than, and vertical lines above the true center. It was suggested that radial and vertical misbisection depended on the presence of an attentional bias toward far/upper space. The aim of the present study was to investigate whether such attentional bias depends on a single mechanism or on separate mechanisms. Ninety participants were asked to bisect lines radially and vertically oriented. The results confirmed the presence of a consistent bisection bias farther than (radial lines), and above (vertical lines) the true center. Furthermore, there was a significant correlation between radial and vertical bisection errors. These findings suggest that a single neural mechanism is involved in producing the attentional bias toward far/upper space.
... Furthermore, ageing effects on spatial attention are reportedly stronger in males than females (Barrett & Craver-Lemley, 2008;Varnava & Halligan, 2007). Also, healthy subjects with left-to-right reading pattern generally show a leftward bias, whereas right-to-left readers show a reduced leftward or a rightward bias (Chokron & De Agostini, 1995;Chokron & Imbert, 1993). While neither age, gender and reading directions has been studied in the context of interactions between alertness and spatial attention, such studies might provide an interesting avenue to refine the mechanisms underlying these interactions. ...
... Script directionality effects have also been noted in a range of production tasks, including figure bisection (e.g., Rinaldi, Di Luca, Henik, & Girelli, 2014;Zivotofsky, 2004) and representational drawing. For example, Chokron and Imbert (1993) found in a line bisection task that French readers placed the middle to the left of the actual midpoint while Hebrew readers bisected the line to the right of the actual midpoint. Similarly, objects with a distinct front, such as a bicycle or an elephant, tend to be drawn facing leftward by left-to-right readers and rightward by right-to-left readers (Kebbe & Vinter, 2013;Vaid, 1995;Vaid, Singh, Sakhuja, & Gupta, 2002). ...
Spatial biases in graphomotor production tasks such as figure drawing may reflect biological (cerebral lateralization), biomechanical (limb movement), and/or cultural (reading/writing direction) influences. The present study examined sources of bias in the placement in graphic space of a symmetrical drawn figure (a tree). A previous study using a child sample found an overall leftward placement bias, independent of participants’ reading/writing direction experience [Picard & Zarhbouch, 2014 Picard, D., & Zarhbouch, B. (2014). Leftward spatial bias in children's drawing placement: Hemispheric activation versus directional hypotheses. Laterality: Asymmetries of Body, Brain and Cognition, 19(1), 96–112.[Taylor & Francis Online], [Web of Science ®] , [Google Scholar]. Leftward spatial bias in children's drawing placement: Hemispheric activation versus directional hypotheses. Laterality: Asymmetries of Body, Brain and Cognition, 19(1), 96–112]; moreover, the left-side bias was greater in right handers. Using an adult sample, the present study also found an overall left placement bias. This effect was significantly greater in right-handed than left-handed participants. Importantly, a left placement bias was significantly greater in left-to-right readers (English) than in participants whose first learned language was from right-to-left (Urdu, Arabic or Farsi). The fact that script directionality is associated with figure placement in our study but not in the previous study suggests that a certain threshold of experience in reading/writing in a given direction may be needed for scanning biases to exert a demonstrable effect on representational drawing. These findings suggest that biomechanical and cultural factors offer a more parsimonious account of spatial biases in drawing.
... Although this behavioral leftward bias is a reliable phenomenon (Jewell and McCourt, 2000), inter-individual variability exists both in the magnitude and the direction of the bias (Manning et al., 1990), and the demonstration of the factors that contribute to the variability of this bias remains open. For example, some studies have shown that visuospatial factors, such as the direction of the visual scanning of the line (Chokron and Imbert, 1993;Brodie and Pettigrew, 1996), the visual hemispace, and the hemispatial body field in which the line is presented (Bowers and Heilman, 1980;Luh, 1995;Mennemeier et al., 1997;McCourt, 1999) contribute to the behavioral attentional bias. When the visual scanning is initially performed from the left, it induced greater leftward deviations compared to right scanning (Brodie and Pettigrew, 1996;Chokron et al., 1998). ...
In a sample of 60 French participants, we examined whether the variability behavioral deviation measured during the classical “paper and pencil” line bisection
task was explained by individual laterality factors such as handedness and eye sighting
dominance, as well as the hand used to bisect, and the spatial position of the line to
bisect. The results showed the expected main effects of line position and hand used
to bisect, as well as some interactions between factors. Specifically, the effect of the
hand used to bisect on the deviation bias was different as a function of handedness and
line position. In right-handers, there was a strong difference between the biases elicited
by each hand, producing a hand-used asymmetry, observed for each spatial position
of the line. In left-handers, there was no difference in deviation as a function of hand
used to perform the bisection, except when all factors triggered attention toward the
left side such as bisecting left-displaced lines, with the left dominant hand, producing a
strong leftward deviation as compared to the reduced bias exhibited with the right nondominant hand. Finally, the eye sighting dominance interacted with handedness and line position. Left-handers with a right sighting dominance showed a leftward bias when they bisected left-displaced lines, while right-handers with a left sighting dominance showed an inversed bias when they bisected rightward lines. Taken together, these findings suggest that the behavioral deviation bias relies on the integration of the hemispheric weights of the visuospatial processing of the stimuli, and the motoric component of the hand used to bisect, as well as those linked to individual laterality factors. When all these factors producing asymmetric cerebral activation coincide in the same direction, then their joint effect will provide the strongest asymmetric behavioral biases.
... Indeed, when line bisections were significantly biased, it was systematically towards the left side of lines. Such deviation towards the left side of space has already been documented in neurologically healthy participants, including during line bisection tests ( [49][50][51][52]; for a review see [53,54]). This leftward spatial bias so-called pseudoneglect has been discussed as reflecting attentional asymmetry due to hemispheric dominance in spatial attention control [55] and an involvement of the right cortical hemisphere controlling the allocation of attention towards both the contralateral and ipsilateral hemispaces [56]. ...
There is growing evidence in the literature suggesting that sensori-motor deficits have a detrimental impact on cognitive abilities, such as the perception and representation of space. Most of the tasks classically used to assess spatial perception abilities after brain damage seem however not adequate to reveal potentially more discrete impairments in patients that are predominantly suffering from sensori-motor symptoms. To this aim we adapted the classic line bisection task in a virtual reality environment for the use with patients with upper-limb sensory-motor deficits. Here, we report the results from two pre-clinical experiments with healthy volunteers. Lines were projected horizontally on a semi-reflective mirror. Participants were asked to bisect the lines at their estimated midpoint by means of a robotic handle. Manipulated factors were the static hand, the position of the static hand (inside or outside of workspace), the visibility of the hands and the location of the lines. Results showed that participants neglected the most lateral part of the lines when they were projected distantly from the starting point. Bisection biases were in general more important when participants could see their hands. Additionally, participants took more time to initiate movements when they had to cover a short distance to reach the lines. We conclude that our robotic adaptation of the line bisection task was able to highlight subtle perceptual asymmetries in healthy individuals and that its use to reveal discrete cognitive deficits in patients with sensory-motor impairments seems therefore promising.
Contextual cueing can depend on global configuration or local item position. We investigated the role of these two kinds of cues in the lateralization of contextual cueing effects. Cueing by item position was tested by recombing two previously learned displays, keeping the individual item locations intact, but destroying the global configuration. In contrast, cueing by configuration was investigated by rotating learned displays, thereby keeping the configuration intact but changing all item positions. We observed faster search for targets in the left display half, both for repeated and new displays, along with more first fixation locations on the left. Both position and configuration cues led to faster search, but the search time reduction compared to new displays due to position cues was comparable in the left and right display half. In contrast, configural cues led to increased search time reduction for right half targets. We conclude that only configural cues enabled memory-guided search for targets across the whole search display, whereas position cueing guided search only to targets in the vicinity of the fixation. The right-biased configural cueing effect is a consequence of the initial leftward search bias and does not indicate hemispheric dominance for configural cueing.
There is a longstanding and widely held misconception about the relative remoteness of abstract concepts from concrete experiences. This review examines the current evidence for external influences and internal constraints on the processing, representation, and use of abstract concepts, like truth, friendship, and number. We highlight the theoretical benefit of distinguishing between grounded and embodied cognition and then ask which roles do perception, action, language, and social interaction play in acquiring, representing and using abstract concepts. By reviewing several studies, we show that they are, against the accepted definition, not detached from perception and action. Focussing on magnitude-related concepts, we also discuss evidence for cultural influences on abstract knowledge and explore how internal processes such as inner speech, metacognition, and inner bodily signals (interoception) influence the acquisition and retrieval of abstract knowledge. Finally, we discuss some methodological developments. Specifically, we focus on the importance of studies that investigate the time course of conceptual processing and we argue that, because of the paramount role of sociality for abstract concepts, new methods are necessary to study concepts in interactive situations. We conclude that bodily, linguistic, and social constraints provide important theoretical limitations for our theories of conceptual knowledge.
Cognitive processes can influence the characteristics of saccadic eye movements. Reading habits, including habitual reading direction, also affects cognitive and visuospatial processes, favouring attention to the side where reading begins. Few studies have investigated the effect of habitual reading direction on saccade directionality of low-cognitive-demand stimuli (such as dots). The current study examined horizontal prosaccade, antisaccade and self-paced saccade in subjects with two primary habitual reading directions. We hypothesised that saccades responding to the target in subject’s habitual reading direction would show a longer prosaccade latency and lower antisaccade error rate (errors being a reflexive glance to a sudden-appearing target, rather than a saccade away from it). Sixteen young Chinese participants with primary habitual reading direction from left to right and sixteen young Arabic and Persian participants with primary habitual reading direction from right to left were recruited. Subjects needed to look towards a 5 o / 10 o target in the prosaccade task or look towards the mirror image location of the target in the antisaccade task and look between two 10-degree targets in the self-paced saccade task. Only Arabic and Persian participants showed a shorter and directional prosaccade latency towards 5 o target against their habitual reading direction. No significant effect of primary reading direction on antisaccade latency towards the correct directions was found. However, we found that Chinese readers generated significantly shorter prosaccade latencies and higher antisaccade directional errors compared with Arabic and Persian readers. The present study provides an insight into the effect of reading habits on saccadic eye movements in response to low-cognitive-demand stimuli and offers a platform for future studies to investigate the relationship between reading habits and neural mechanisms of eye movement behaviours.
The spatial agency bias predicts that people whose native language is rightward written will predominantly envisage action along the same direction. Two mechanisms contribute jointly to this asymmetry: (a) an embodied process related to writing/reading; (b) a linguistic regularity according to which sentence subjects (typically the agent) tend to precede objects (typically the recipient). Here we test a novel hypothesis in relation to the second mechanism, namely, that this asymmetry will be most pronounced in languages with rigid word order. A preregistered study on 14 European languages ( n = 420) varying in word order flexibility confirmed a rightward bias in drawings of interactions between two people (agent and recipient). This bias was weaker in more flexible languages, confirming that embodied and linguistic features of language interact in producing it.
Most people tend to explore space starting from the left side, a bias that can also be found in cancellation and line bisection tasks. This spatial bias, known as pseudoneglect, is modulated by biological and cultural factors. Traditional paper-and-pencil tests are affected by ecological and sensitivity issues. Recently, we developed an enhanced version of the Baking Tray Task (BTT), based on E-TAN a digital platform that supports tangible interfaces. The E-BTT, enhanced version of the BTT, aims to investigate visuospatial behaviors in the proximal space in an ecological way through a more precise, informative and automatic data collection. Given the evidence from the scientific literature of a task effect on pseudoneglect, the aim of the present study is to explore the spatial behavior in peripersonal space in a sample of university students aged from 18 to 26, by means of different visuospatial tasks, using tangible tools, such as the E-BTT, and digital ones based on touch-sensitive devices, such as cancellation, line bisection and digitized radial arm maze tasks. Forms of pseudoneglect, except for the radial arm maze, were detected in all the examined tasks although there are no significant correlations between them. This could be related to inherent differences in tasks, non-linear relationships, or specific anatomical asymmetries. Clusters analysis results seem to support these last two hypotheses, because in two clusters out of four we found moderate to strong positive correlations between E-BTT, cancellation and line bisection tasks.
In the adult brain, biases in the allocation of spatial attention can be measured using a line bisection task and are directly relatable to neural attention signals in the fronto‐parietal attention network. Behavioral studies on the development of spatial biases have yielded a host of inconsistent results, likely due to variance in sample size, definition of experimental groups, and motor confounds introduced by using a paper‐and‐pencil version of a line bisection task. Here, we used a perceptual, computerized version of this task and examined the development of spatial biases in 459 children from grades 1‐8 and 61 college freshmen. We found that children in early elementary grades exerted a significant leftward bias that gradually diminished with advancing grade level. We further show that among children in early elementary school grades, the degree of leftward spatial bias predicted better performance on a rapid automatized naming (RAN) test, a predictor of reading ability. Significant leftward biases in early elementary school grades may be due to reading experience, thereby reflecting an interaction of the attention network with the evolving reading network.
Pseudoneglect refers to a tendency of neurologically healthy individuals to produce leftward perceptual biases during spatial tasks, which is traditionally measured using line bisection tasks. This behavioral asymmetry is often explained as a consequence of right hemispheric dominance for visuospatial attention. The present study directly tested this notion by comparing line bisection performance between left-handers with either right hemispheric dominance (RVSD, N = 40) or “atypical” left hemispheric dominance (LVSD, N = 23) for visuospatial attention as determined by fMRI. Although we expected a reversal of pseudoneglect in participants with LVSD, our results show that they equally often err to the left of the true center compared to RVSD controls (74% of LVSD participants and 80% of RVSD participants). However, the magnitude of misbisections was found to be slightly, but significantly, smaller in the LVSD subgroup.We conclude that hemispheric asymmetry for visuospatial attention is not the main determinant of pseudoneglect as is commonly thought, but rather only constitutes one of the multiple factors which (subtly) contributes to its direction and magnitude.
Virtual Reality environments provide an immersive experience for the user. Since humans see the real world in 3D, being placed in a virtual environment allows the brain to perceive the virtual world as a real environment. This paper examines the contrasts between two different user interfaces by presenting test subjects with the same 3D environment through a traditional flat screen (pancake) and an immersive virtual reality (VR) system. The participants (n = 31) are computer literate and familiar with computer generated virtual worlds. We recorded each user’s interactions while they undertook a short-supervised play session with both hardware options to gathering objective data; with a questionnaire to collect subjective data, to gain an understanding of their interaction in a virtual world. The information provided an opportunity to understand how we can influence future interface implementations used in the technology. Analysis of the data has found that people are open to using VR to explore a virtual space with some unconventional interaction abilities such as using the whole body to interact. Due to modern VR being a young platform very few best practice conventions are known in this space compared to the more established flat screen equivalent.
Visual perception is often not homogenous across the visual field and can vary depending on situational demands. The reasons behind this inhomogeneity are not clear. Here we show that directing attention that is consistent with a western reading habit from left to right, results in a ~32% higher sensitivity to detect transient visual events in the right hemifield. This right visual field advantage was largely reduced in individuals with reading difficulties from developmental dyslexia. Similarly, visual detection became more symmetric in skilled readers, when attention was guided opposite to the reading pattern. Taken together, these findings highlight a higher sensitivity in the right visual field for detecting the onset of sudden visual events that is well accounted for by left hemisphere dominated reading habit.
Neurologically healthy individuals exhibit subtle attentional asymmetries, such that attention is preferentially directed leftwards for objects in near space and rightwards for objects in far space. These attentional biases also affect navigation and cause people to deviate to the right when passing through an aperture. The current study examined whether the rightward deviations observed in real-world environments translate to simulated environments. As proof of concept and to determine whether rightward biases could be further exacerbated, the degree of cognitive load imposed on participants was manipulated. Experiment 1 asked participants to navigate through the centre of a computer-based doorway. In one block of trials, participants completed the task by itself (baseline condition), while in another block of trials they also completed a simple auditory discrimination task (load condition). While analyses revealed rightward biases for both conditions, the difference between conditions was not significant. Experiment 2 therefore increased the difficulty of the auditory task. Analyses revealed a significant difference between conditions, suggesting that the degree of cognitive load further exacerbates rightward biases, demonstrating that the rightward asymmetries in navigation observed in the real world generalises to a simulated environment and that this phenomenon behaves in a way that is consistent with pseudoneglect.
A visual attention span (VAS) deficit has been widely reported in the Developmental Dyslexia (DD) literature, however, consensus regarding what underlies this problem and the nature of its relationship with reading ability remains elusive. Thirty-two children with DD (15 females) were compared with 23 age matched (12 females) and 17 reading matched controls (9 females) on the combined Theory of Visual Attention (CombiTVA) paradigm with traditional letter and novel symbol conditions. The DD group performed more slowly than the age matched controls in terms of processing speed, but similarly to reading matched controls. Moderation analyses revealed that the difference between the DD group and age matched controls was driven by children with equivalent, or relatively poorer, lexical compared with sublexical reading profiles. Results suggest that reduced processing speed indexes reading immaturity, particularly in DD individuals with relative lexical reading deficits, rather than being a unique contributor to reading dysfunction.
The objective of this study was to administer line bisection (LB) and symbol cancellation (SC) tasks on a sample of healthy Arabs in Saudi Arabia, to determine if normative performance would differ from that of the Western population. A total of 136 healthy individuals were enrolled. Deviation direction from the veridical center and percentage deviation scores (PDS) were determined for LB. The overall performance on SC was calculated. Differences according to gender, education and age were measured. Out of the 2,287 times lines were bisected, 1025 (44.82%) deviated rightward (p < 0.0001). Mean (SD) PDS showed a rightward bias 1.57(3.4), (p < 0.0001). Rightward deviation odds modestly increased with age (OR 1.04, P 0.038). In SC, 63% started searching from the left and 67.5% used a horizontal strategy. The mean (SD) performance score was 0.468 (0.248) with no significant cancellation asymmetry. Female gender, education, and age significantly associated with performance. No correlation was found between the two tasks (p = 0.09). Line bisection error biases in Arabs are opposite of Western biases. Scanning for symbols started on the left side; however, this was smaller than that seen in existing Western reports. Normative performances are different from Western studies, but similarly influenced by the same demographic variables.
Previous studies showed that the small leftward bias found in healthy humans’ spatial judgments of lines (“pseudoneglect”) shifts to the right with increasing distance between stimuli and observer. In this study, we investigated whether such a modulation of attentional asymmetry can also be observed in free visual exploration. Participants freely explored photographs of naturalistic scenes for 7 s in near (60 cm) and far (140 cm) space. After an initial leftward bias, followed by a compensatory rightward bias, gaze positions were significantly more leftward in near compared to far space (around 4 s from scene onset). Our results show that the modulation of attentional asymmetries by viewing distance previously reported for spatial judgments generalizes to free visual exploration, and we revealed the temporal dynamics of these asymmetries by fine-grained eye movement analysis. In contrast, an effect of viewing distance was reduced or absent when eye movements are under strong top-down control, as in systematic serial visual search (Sensitive Negelct Test). Finally, there was no effect of viewing distance in the landmark task (as also reported in a minority of other studies), suggesting that this effect may depend on specific, yet unidentified task characteristics.
Previous studies showed that healthy individuals bisect radial lines oriented along the midsagittal plane farther than the true center (distal bisection bias). It was proposed that the distal bisection bias depended on the presence of an attention bias directed toward far space (distal attention bias) and that this bias is related to the activity of the occipitotemporal visual processing stream. Other studies have also suggested that a similar distal attention bias is linked to the activity of the right hemisphere. In the present experiment we investigated whether distal bisection bias increased when radial lines were placed in the left hemispace. Furthermore, we also examined whether the bisection bias was enhanced by the use of the left hand, as left hand movements are mainly controlled by the right hemisphere. Right-handed participants were asked to bisect radial lines presented below eye level along the midsagittal plane (central lines), or laterally and parallel to the midsagittal plane, in the left or right hemispace (left and right lines, respectively). Participants used their right or left hand. The results showed that participants consistently bisected left and central radial lines farther than (i) the true center and (ii) the subjective midpoint of right radial lines. Conversely, they bisected accurately right radial lines. The hand did not influence bisection error. The present study suggests that the distal bisection bias found in the bisection of left radial lines might depend on the presence of a distal attention bias related to right hemisphere activity. The relative contribution of retinotopic and spatiotopic factors in producing the distal bisection bias is discussed.
Our motor behavior and interactions with the external world are mediated by many spatial systems. This study investigated the absence of visual control of performance in the manual line bisection task, with the goal of teasing apart the role of the motor component of the visuomotor spatial system. Results show a rightward bias when right-handed individuals bisect lines using their right hand. This effect is traced back to a motor-spatial representation of space centered on the dominant hand. This finding was replicated and further explored in 4 experiments, with the same “open loop” bisection procedure. The mechanism underlying the rightward bias does not interact with the visuo-perceptual processing involved in visual illusions of extension. Besides, this bias no longer appears when perceptual judgments of prebisected lines are required, and is substantially reduced when the influence of visual feedback is minimized by a ballistic movement. The emergence of a leftward shift in left-handed individuals, when using their left hand, confirms the hypothesis of a dominant-hand-centered motor-spatial bias. Finally, when the lines to be bisected are placed to the left or to the right of the midsagittal plane of the participants’ trunk, the error shifts overall toward the side of displacement of the stimulus, both in left- and right-handers, independent of the bisection bias, which does not appear related to the egocentric position of the stimulus. We reexamined the spatial biases occurring both in healthy (i.e., pseudoneglect) and neurological (i.e., neglect) populations, by emphasizing the integration mechanism of different spatial coordinate systems.
Native Israeli readers read Hebrew and English text as their eye movements were monitored. A window of text moved in synchrony with their eye movements and the window was either symmetrical about the fixation point or offset to the left or right. When subjects were reading Hebrew, the perceptual span was asymmetric to the left and when they were reading English it was asymmetric to the right. The results point out the importance of attentional factors in reading.
When solving verbal problems, right-handed people usually turn head and eyes to the right, whereas with numerical and spatial problems, these people look up and left. Left-handed people differ in all these respects. The results suggest that the direction in which people look while thinking reflects the lateralization of the underlying cerebral activity.
Unilateral neglect may be considered with reference to several spatial-coordinate systems, e.g., those relating to the body midline, head and retina, and seems to involve alterations in the deployment of attention. Left hemineglect may be more frequent or, possibly, merely more salient than right hemineglect, perhaps because of asymmetries in the representation of extracorporeal space. In normal subjects we have reported a number of analogous phenomena. Visually presented lines or tactually/kinesthetically presented rods were typically transected slightly to the left of the true midpoint, an effect which could be manipulated by varying the salience of the two extremities. In a variety of tactuomotor tasks involving the fingers, the position in space to left or right of the body was found to be more important than the actual hand (left or right) employed, which was placed either on its own side of the body or across the midline to the opposite side. In vibrotactile reaction time experiments, performance was also found to be determined by the position of the responding hand, though hand asymmetries replaced hemispace asymmetries under conditions of stimulus uncertainty. In the auditory modality, it was the position, real or perceived (as under conditions of visual capture) of a sound source (loudspeaker) which determined performance asymmetries. In all these experiments asymmetries were lost by dissociating the head and body coordinate systems, through the maintenance of a 90° head turn to left or right, or by the dissociation of the gravitational and corporeal coordinate systems, when lying horizontallly upon the left or right side. The hemispheres may map both proximal sensory (and motor) events involving the body surface and more distal events occurring out in extracorporeal space. These two representations may be experimentally dissociated.
Visual scanning studies involving more than one cultural group have demonstrated differences in scanning behavior. These studies have all used recall to test for scanning patterns. Eye movement research, which directly records scanning behavior, has traditionally employed Western subjects. The present experiment used eye movement photography to study cultural influences on visual scanning patterns. Thirty adult subjects were tested, representing the Western, Middle Eastern, and East Asian cultures. Data on location of fixations and direction of saccades (horizontal or vertical and right to left or left to right) were collected. No significant differences were found for location of fixations. Data on the direction of saccades revealed significant differences, all of which reflected the reading habits of the different cultures. These data corroborated the results of previous cross-cultural studies.
English and Hebrew words were exposed tachistoscopically to native Hebrew readers to the left or right of fixation. English was invariably better recognized in the right visual field though right-handers showed a greater recognition differential than left-handers. No significant recognition differential was obtained using Hebrew words. However, right-handers recognized more Hebrew words in the right visual field and left-handers identified more Hebrew words in the left visual field, and this difference was significant. It is argued that directional scanning, selective attention, cerebral dominance and structural factors all influence the left-right recognition differential.
Two versions of a line bisection task were given to patients with posterior right-hemisphere damage and normal control subjects. One, which we refer to as the directed-manual task, was the traditional bisection task in which lines were transected with a pen held in the right hand. In the other task, referred to as the directed-visual task, subjects observed the experimenter move a pen along a line from right-to-left (the left-scan task) or from left-to-right (the right-scan task) and they verbally indicated the subjective midpoint. Patients showed significant left neglect in the manual and the left-scan tasks only. Controls showed no consistent biases and no influence of scanning direction. Right and left cues biased bisection for both groups. The results indicate that when the directed manual response is eliminated, scan direction determined the presence or absence of neglect on bisection. The findings are discussed in terms of the efficiency of visual orienting.
The purpose of this study was to determine whether tactile laterality effects can be attributed to an anatomical pathway-transmission model or to some hemispheric mechanism involved in the perception and/or mediation of activities in the contralateral hemispatial field. Hemispace is not the same as the visual half field, but refers to the external space to the left or right of body midline. To differentiate between these two hypotheses, 24 normal dextrals performed a tactile line bisection task using the left or right hand in each of three spatial conditions: at midline, in left hemispace and right hemispace. The findings indicated that both hemisphere-hemispace mechanisms and hemisphere-hand connections contributed to laterality effects. Furthermore, a pseudoneglect phenomenon was observed.
Handedness was assessed in 620 men and 487 women, using both the CrovitzZener and Oldfield questionnaires. Factor analysis of the individual items revealed three factors: a primary handedness factor, and two factors that are idiosyncratic to the wording of the questions. On the basis of the analysis, shortened versions of the two tests are recommended. These shortened versions are both reliable and valid, and show significant correlations with parental handedness. Men are consistently more likely to be left-handed than women, but much of this is due to a tendency for men to avoid extreme responses.
Two experiments were carried out to examine specific hand contribution to pseudoneglect and reversed pseudoneglect phenomena in dextrals and sinistrals when bisection tasks were conducted exclusively in the midline spatial condition. Both dextrals and sinistrals showed the same overall pattern deviation: in the tactile scanning task, both right and left hands deviated to the left of the midpoint and in the kinesthetic scanning tasks, the right hand deviated to the left and the left hand to the right of the midpoint. However, when these deviations were tested against zero (i.e. the objective midpoint) clear differences appeared related to hand, task and handedness. These results were discussed with respect to "enhancement theory".
Two experiments were conducted with right-handed adult subjects to investigate motor and sensory components of a tactual line bisection task performed under three conditions: at midline, in the left, and in the right hemispaces. In the sensory experiment we found a left-hand rather than a right-hand superiority under the midline condition and, in the motor experiment, a right-hand rather than a left-hand superiority. The results were discussed with respect to hemispheric specialization and hemispace theories. Furthermore, we found a pseudoneglect (subjects bisected to the left of the midpoint) in the sensory experiment and a surprising reversed pseudoneglect (subjects bisected to the right of the midpoint) in the motor experiment.
We report a case of mild visuo-spatial neglect consequent upon right-hemisphere stroke. At the time of testing, the patient had a complete left visual field deficit but only a very slight left hemiparesis. Under conventional testing conditions, line bisection performed with the right hand showed more severe left neglect than when performed with the left hand. This pattern of performance could, however, be modified, both quantitatively and qualitatively, by changing the starting position of the patient's hand when bisecting horizontal lines. The results suggest that spatio-motor cueing has a more profound effect upon task performance than does differential hemispheric activation per se. We also provide a demonstration that, in a normal subject, the starting position of the hand is likewise a crucial determinant of task performance. In this case, however, there is also an interaction between the hand (and hence hemisphere) deployed and the position of that hand in space.
Investigations of left visuo-spatial neglect are reviewed with special reference to line bisection performance. Attention is then drawn to inconsistencies in the direction and magnitude of transection displacements in group studies of normal controls. We argue that the lack of reliable information about normal mechanisms for line bisection makes it impossible to interpret pathological performance in neglect. Accordingly, we report a case-series of 22 normal young adults, each of whom bisects 10 lines of differing lengths 10 times each. There is very substantial between-subject variation in both the magnitude and direction of the linear regression of transection displacement on line length; there are likewise considerable differences in the magnitude of the linear regression of standard deviation on line length. These two sources of individual variation are uncorrelated. We propose a psychophysical theory of line bisection, and suggest that the basic mechanisms responsible for task-performance are qualitatively intact in visuo-spatial neglect, albeit quantitatively impaired.
The aim of this study was to assess whether perceptual representation along the horizontal axis is affected by hemispace position of the stimulus or by orienting attention to one side. Ten control subjects and 10 right brain damaged patients with left unilateral spatial neglect (USN) were asked to bisect lines of five lengths in three space positions (left, center, right) and under three cueing conditions (no cue, left cue, right cue). Normal controls showed significant displacement of bisection opposite to the side of hemispace presentation and toward the side of cueing. USN patients showed a bisection error toward the right end which increased with lines placed in the left hemispace and decreased with lines placed in the right hemispace and when attention was oriented toward the left side. We conclude that (1) In absence of cues normal subjects tend to overestimate the portions of space closer to their body midline; (2) both normal and USN patients tend to overestimate portions of space that they direct their attention to; (3) USN patients' performance without cueing is consistent with an attentional shift toward the right hemispace implying a gradient of overestimation of the right-most portions of space. A common neural substratum for directing attention and space representation can explain these findings.
Subjects set the extremities of a horizontal rod to appear equidistant from a central reference point, with or without central fixation. On either side, the contrast (salience) of the rod against the background was high or low. Extents to the left were set smaller than those to the right, an effect (LSU) which was stronger with central fixation, indicating that both hemispatial and anatomical pathway factors contribute. Reduced salience on the left increased rather than decreased the LSU, indicating the importance of attentional factors.
Right- and left-handed subjects performed a visual line bisection task with each hand. When bisecting horizontal lines, both groups bisected left of true center regardless of hand used. Regardless of hand preference, bisections were significantly left of center only when subjects performed with their left hand. Left-handed subjects using their left hand deviated significantly further left than right-handed subjects using their left hand. Regardless of hand used, right-handers bisected vertical lines significantly above veridical center. Left-handed subjects were not significantly above center with either hand. The results require both hemispheric advantage and lateralized activation effects for a complete explanation.
In Experiment I normal subjects performed the classical clinical line-bisection task, and demonstrated a left-side underestimation. In Experiment II subjects maintained fixation upon a central position and adjusted a rod passing through this fixation point so that both extremities were judged equal. The left-side underestimation was very much greater under these conditions, but was considerably reduced when retinal and gravitational coordinates were dissociated by making the subjects lie horizontally on one or other side. Subjects then demonstrated greater left-side and top-half underestimation when lying on the left than on the right side. Gravitational coordinates and the apparent locus of events in extrapersonal space are determinants of perceptual asymmetries at least as important as anatomical connectivities.
Asymmetries in the processing of input to either side of the midline are related to hemispheric specialization in man. These asymmetries arise when preponderant activation of one hemisphere biases attention to the contralateral side. This unbalanced cerebral activation is a function of the nature of the subject's task or expectancy. A model of hemispheric integration is proposed.
In this study, the role of lateral cerebral dominance in the consistent finding of lower tachistoscopic thresholds in the right than in the left visual field for alphabetic material was tested for readers of Hebrew and English. Twenty Israeli Ss were presented with Hebrew and English three-letter words, printed vertically, through a monocular tachistoscope, displaced to left or right of fixation by 2°21′. Ten American Ss were also tested for three-letter English words, under similar conditions. Significantly lower thresholds in the right field were found for both groups and for both languages, despite the fact that Hebrew, unlike English, is read from right to left. These findings tend to support the hypothesis that alphabetic stimuli arriving in the major cerebral hemisphere are more readily recognized than similar stimuli arriving in the hemisphere contralateral to the language areas.
Laterally presented verbal stimuli nowadays frequently include words and letter strings, as well as the more traditional single-character alphanumeric materials. In addition to studying hemisphere differences in word processing in their own right, these studies often use word materials as tools in investigating such factors as sex, handedness, practice, familiarity, and developmental aspects. Doubt has been expressed, partly on the basis of some earlier studies involving unilaterally and bilaterally presented word and letter strings, English, Hebrew, and Yiddish, in normal and mirror-reversed orientation, whether the obtained right-visual-field (RVF) superiorities are a function of cerebral dominance or of left-to-right directional processing or scanning, associated with Western reading habits. More recent and better controlled studies are reviewed which bear upon this issue, including some where words are presented in a vertical organization, together with current theories of word recognition. It is concluded that at least with unilateral presentations, in the absence of any central “fixation” digit, single-syllable words can safely be employed in the knowledge that any resultant field differences are likely to reflect neural organization, and that any directional scanning or processing artifacts make, at the most, a minor contribution.
Normal dextrals performed tactilo-kinesthetic bisection tasks in a median position, at three directions of gaze: 30 degrees to the left, 30 degrees to the right, 0 degree. Instead of pseudoneglect phenomenon, a deviation of the subjective middle to the side opposite to the direction of gaze and hand use was found, whichever hand was used. The results are interpreted in terms of displacement of the position of the egocentric reference and are discussed with respect to activation theory. It is argued that pseudoneglect is part of a more general asymmetric perception of space phenomenon which depends on the position of the egocentric reference.
Pseudoneglect: effects of hemispace on a tactile bisection line task
- Bowers
Scanning direction and line bisection
- Chokron
Pseudoneglect and reversed pseudoneglect
- Sampaio