Ovid J L Tzeng

Academia Sinica, T’ai-pei, Taipei, Taiwan

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Publications (77)407.95 Total impact

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    ABSTRACT: Emotional faces are often salient cues of threats or other important contexts, and may therefore have a large effect on cognitive processes of the visual environment. Indeed, many behavioral studies have demonstrated that emotional information can modulate visual attention and eye movements. The aim of the present study was to investigate (1) how irrelevant emotional face distractors affect saccadic behaviors and (2) whether such emotional effects reflect a specific neural mechanism or merely biased selective attention. We combined a visual search paradigm that incorporated manipulation of different types of distractor (fearful faces or scrambled faces) and delivered anodal transcranial direct current stimulation (tDCS) over the superior temporal sulcus and the frontal eye field to investigate the functional roles of these areas in processing facial expressions and eye movements. Our behavioral data suggest that irrelevant emotional distractors can modulate saccadic behaviors. The tDCS results showed that while rFEF played a more general role in controlling saccadic behavior, rSTS is mainly involved in facial expression processing. Furthermore, rSTS played a critical role in processing facial expressions even when such expressions were not relevant to the task goal, implying that facial expressions and processing may be automatic irrespective of the task goal.
    Neuropsychologia 09/2014; · 3.48 Impact Factor
  • Yi-hui Hung, Daisy L. Hung, Ovid J.-L. Tzeng, Denise H. Wu
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    ABSTRACT: The majority of Chinese characters are composed of a semantic and a phonetic radical. Although pre-lexical involvement of the phonetic radical in Chinese character recognition has been established, there is little agreement on the contribution of the semantic radical. We used magnetoencephalography (MEG) to investigate the temporal dynamics of the priming effect elicited by repetition of phonetic and semantic radicals in the tasks of homophone and synonym judgment, respectively. The behavioral results revealed robust priming induced by both kinds of radicals. As for the MEG results, the repetition effect of phonetic radicals was obtained in the M170, M250 and M350 components. However, the repetition effect of semantic radicals was only marginally interactive with other variables in the M170, M350 and M450 components. The present findings suggest that phonetic radicals play a predominant role in early lexical access and phonological computation of Chinese character recognition, while semantic radicals have relatively weak effect on lexical access and semantic retrieval.
    Journal of Neurolinguistics 05/2014; · 1.12 Impact Factor
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    ABSTRACT: The effect of hand proximity on vision and visual attention has been well documented. In this study we tested whether such effect(s) would also be present in the auditory modality. With hands placed either near or away from the audio sources, participants performed an auditory-spatial discrimination (Experiment 1: left or right side), pitch discrimination (Experiment 2: high, med, or low tone), and spatial-plus-pitch (Experiment 3: left or right; high, med, or low) discrimination task. In Experiment 1, when hands were away from the audio source, participants consistently responded faster with their right hand regardless of stimulus location. This right hand advantage, however, disappeared in the hands-near condition because of a significant improvement in left hand's reaction time (RT). No effect of hand proximity was found in Experiments 2 or 3, where a choice RT task requiring pitch discrimination was used. Together, these results that the perceptual and attentional effect of hand proximity is not limited to one specific modality, but applicable to the entire "space" near the hands, including stimuli of different modality (at least visual and auditory) within that space. While these findings provide evidence from auditory attention that supports the multimodal account originally raised by Reed et al. (2006), we also discuss the possibility of a dual mechanism hypothesis to reconcile findings from the multimodal and magno/parvocellular account.
    Frontiers in Psychology 01/2014; 5:527. · 2.80 Impact Factor
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    ABSTRACT: In this study, we examine the neural substrates underlying Tone 3 sandhi and tone sequencing in Mandarin Chinese using fMRI. Tone 3 sandhi is traditionally described as the substitution of Tone 3 with Tone 2 when followed by another Tone 3 (i.e., 33→23). According to current speech production models, target substitution is expected to engage the posterior inferior frontal gyrus. Since Tone 3 sandhi is, to some extent, independent of segments, which makes it more similar to singing, right-lateralized activation in this region was predicted. As for tone sequencing, based on studies in sequencing, we expected the involvement of the supplementary motor area. In the experiments, participants were asked to produce twelve four-syllable sequences with the same tone assignment (the repeated sequences) or a different tone assignment (the mixed sequences). We found right-lateralized posterior inferior frontal gyrus activation for the sequence 3333 (Tone 3 sandhi) and left-lateralized activation in the supplementary motor area for the mixed sequences (tone sequencing). We proposed that tones and segments could be processed in parallel in the left and right hemispheres, but their integration, or the product of their integration, is hosted in the left hemisphere.
    PLoS ONE 01/2014; 9(1):e83126. · 3.53 Impact Factor
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    ABSTRACT: Many studies have used event-related potential and neural oscillations to probe the underlying neural mechanisms of inhibitory control in adults, but little has been done in typically developing preschoolers. In this study we tested healthy preschool children between the ages of 5 and 6, and observed better response inhibition in 6-year-olds compared to 5-year-olds. Importantly, this age-related difference could not be explained by the N2 component from event-related potential, but was reflected in an increase in right frontal beta power from electroencephalogram. These results suggest that frontal beta power during the preschool period may reflect neural development of inhibitory control.
    Developmental Neuropsychology 07/2013; 38(5):301-16. · 2.90 Impact Factor
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    ABSTRACT: Inhibitory control, or the ability to suppress planned but inappropriate prepotent actions in the current environment, plays an important role in the control of human performance. Evidence from empirical studies utilizing a sport-specific design has shown that athletes have superior inhibitory control. However, less is known about whether this superiority might (1) still be seen in a general cognitive task without a sport-related context; (2) be modulated differentially by different sporting expertise (e.g., tennis versus swimming). Here we compared inhibitory control across tennis players, swimmers and sedentary non-athletic controls using a stop-signal task without a sport-specific design. Our primary finding showed that tennis players had shorter stop-signal reaction times (SSRTs) when compared to swimmers and sedentary controls, whereas no difference was found between swimmers and sedentary controls. Importantly, this effect was further confirmed after considering potential confounding factors (e.g., BMI, training experience, estimated levels of physical activity and VO2max), indicative of better ability to inhibit unrequired responses in tennis players. This suggests that fundamental inhibitory control in athletes can benefit from open skill training. Sport with both physical and cognitive demands may provide a potential clinical intervention for those who have difficulties in inhibitory control.
    PLoS ONE 02/2013; 8(2):e55773. · 3.53 Impact Factor
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    ABSTRACT: The dorsal attentional network is known for its role in directing top-down visual attention toward task-relevant stimuli. This goal-directed nature of the dorsal network makes it a suitable candidate for processing and extracting predictive information from the visual environment. In this review we briefly summarize some of the findings that delineate the neural substrates that contribute to predictive learning at both levels within the dorsal attentional system: including the frontal eye field (FEF) and posterior parietal cortex (PPC). We also discuss the similarities and differences between these two regions when it comes to learning predictive information. The current findings from the literature suggest that the FEFs may be more involved in top-down spatial attention, whereas the parietal cortex is involved in processing task-relevant attentional influences driven by stimulus salience, both contribute to the processing of predictive cues at different time points.
    Frontiers in Human Neuroscience 01/2013; 7:404. · 2.91 Impact Factor
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    ABSTRACT: Do the neural circuits for reading vary across culture? Reading of visually complex writing systems such as Chinese has been proposed to rely on areas outside the classical left-hemisphere network for alphabetic reading. Here, however, we show that, once potential confounds in cross-cultural comparisons are controlled for by presenting handwritten stimuli to both Chinese and French readers, the underlying network for visual word recognition may be more universal than previously suspected. Using functional magnetic resonance imaging in a semantic task with words written in cursive font, we demonstrate that two universal circuits, a shape recognition system (reading by eye) and a gesture recognition system (reading by hand), are similarly activated and show identical patterns of activation and repetition priming in the two language groups. These activations cover most of the brain regions previously associated with culture-specific tuning. Our results point to an extended reading network that invariably comprises the occipitotemporal visual word-form system, which is sensitive to well-formed static letter strings, and a distinct left premotor region, Exner's area, which is sensitive to the forward or backward direction with which cursive letters are dynamically presented. These findings suggest that cultural effects in reading merely modulate a fixed set of invariant macroscopic brain circuits, depending on surface features of orthographies.
    Proceedings of the National Academy of Sciences 11/2012; · 9.81 Impact Factor
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    ABSTRACT: The limits of human visual short-term memory (VSTM) have been well documented, and recent neuroscientific studies suggest that VSTM performance is associated with activity in the posterior parietal cortex. Here we show that artificially elevating parietal activity via positively charged electric current through the skull can rapidly and effortlessly improve people's VSTM performance. This artificial improvement, however, comes with an interesting twist: it interacts with people's natural VSTM capability such that low performers who tend to remember less information benefitted from the stimulation, whereas high performers did not. This behavioral dichotomy is explained by event-related potentials around the parietal regions: low performers showed increased waveforms in N2pc and contralateral delay activity (CDA), which implies improvement in attention deployment and memory access in the current paradigm, respectively. Interestingly, these components are found during the presentation of the test array instead of the retention interval, from the parietal sites ipsilateral to the target location, thus suggesting that transcranial direct current stimulation (tDCS) was mainly improving one's ability to suppress no-change distractors located on the irrelevant side of the display during the comparison stage. The high performers, however, did not benefit from tDCS as they showed equally large waveforms in N2pc and CDA, or SPCN (sustained parietal contralateral negativity), before and after the stimulation such that electrical stimulation could not help any further, which also accurately accounts for our behavioral observations. Together, these results suggest that there is indeed a fixed upper limit in VSTM, but the low performers can benefit from neurostimulation to reach that maximum via enhanced comparison processes, and such behavioral improvement can be directly quantified and visualized by the magnitude of its associated electrophysiological waveforms.
    Journal of Neuroscience 08/2012; 32(31):10554-61. · 6.91 Impact Factor
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    ABSTRACT: Witnessing emotional events such as arousal or pain may impair ongoing cognitive processes such as inhibitory control. We found that this may be true only half of the time. Erotic images and painful video clips were shown to men and women shortly before a stop signal task, which measures cognitive inhibitory control. These stimuli impaired inhibitory control only in men and not in women, suggesting that emotional stimuli may be processed with different weights depending on gender.
    Cognition 05/2012; 124(2):251-5. · 3.63 Impact Factor
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    ABSTRACT: Many studies have used static and non-biologically related stimuli to investigate bistable perception and found that the percept is usually dominated by their intrinsic nature with some influence of voluntary control from the viewer. Here we used a dynamic stimulus of a rotating human body, the silhouette spinner illusion, to investigate how the viewers' intentions may affect their percepts. In two experiments, we manipulated observer intention (active or passive), fixation position (body or feet), and spinning velocity (fast, medium, or slow). Our results showed that the normalized alternating rate between two bistable percepts was greater when (1) participants actively attempted to switch percepts, (2) when participants fixated at the spinner's feet rather than the body, inducing as many as 25 switches of the bistable percepts within 1 min, and (3) when they watched the spinner at high velocity. These results suggest that a dynamic biologically-bistable percept can be quickly alternated by the viewers' intention. Furthermore, the higher alternating rate in the feet condition compared to the body condition suggests a role for biological meaningfulness in determining bistable percepts, where 'biologically plausible' interpretations are favored by the visual system.
    Vision research 03/2012; 60:34-9. · 2.29 Impact Factor
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    ABSTRACT: The interaction between goal-directed and stimulus-driven attentional control allows humans to rapidly reorient to relevant objects outside the focus of attention-a phenomenon termed contingent reorienting. Neuroimaging studies have observed activation of the ventral and dorsal attentional networks, but specific involvement of each network remains unclear. The present study aimed to determine whether both networks are critical to the processes of top-down contingent reorienting. To this end, we combined the contingent attentional capture paradigm with the use of transcranial magnetic stimulation (TMS) to interfere with temporoparietal junction (TPJ; ventral network) and frontal eye field (dorsal network) activity. The results showed that only right TPJ (rTPJ) TMS modulated contingent orienting. Furthermore, this modulation was highly dependent on visual fields: rTPJ TMS increased contingent capture in the left visual field and decreased the effect in the right visual field. These results demonstrate a critical involvement of the ventral network in attentional reorienting and reveal the spatial selectivity within such network. Hum Brain Mapp, 2012. © 2012 Wiley Periodicals, Inc.
    Human Brain Mapping 03/2012; · 6.88 Impact Factor
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    ABSTRACT: The present study examined the use of statistical cues for word boundaries during Chinese reading. Participants were instructed to read sentences for comprehension with their eye movements being recorded. A two-character target word was embedded in each sentence. The contrast between the probabilities of the ending character (C2) of the target word (C12) being used as word beginning and ending in all words containing it was manipulated. In addition, by using the boundary paradigm, parafoveal overlapping ambiguity in the string C123 was manipulated with three types of preview of the character C3, which was a single-character word in the identical condition. During preview, the combination of C23′ was a legal word in the ambiguous condition and was not a word in the control condition. Significant probability and preview effects were observed. In the low-probability condition, inconsistency in the frequent within-word position (word beginning) and the present position (word ending) lengthened gaze durations and increased refixation rate on the target word. Although benefits from the identical previews were apparent, effects of overlapping ambiguity were negligible. The results suggest that the probability of within-word positions had an influence during character-to-word assignment, which was mainly verified during foveal processing. Thus, the overlapping ambiguity between parafoveal words did not interfere with reading. Further investigation is necessary to examine whether current computational models of eye movement control should incorporate statistical cues for word boundaries together with other linguistic factors in their word processing system to account for Chinese reading. KeywordsChinese reading–Eye movements–Word processing–Word segmentation cues
    Reading and Writing 01/2012; 25(5):1007-1029. · 1.44 Impact Factor
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    ABSTRACT: To reproduce the duration of an event precisely, one needs to represent the temporal information without being influenced by other magnitude attributes (e.g., size) of the event. In the present study, however, task-irrelevant numerical magnitude automatically affected participants' reproduction of the duration of a stimulus. In Experiment 1, participants made key-press responses to reproduce the duration of numbers. Reproduced durations were shorter for small numbers (e.g., 1) than for large numbers (e.g., 9). In contrast, in Experiment 2, participants' reproductions of a standard duration were longer when their key-press response was accompanied by visual presentation of a small number than when it was accompanied by presentation of a large number. These results clearly demonstrate that number-time interference extends beyond simple mapping between stimulus categories and response alternatives. The findings support the notion that either a common magnitude representation or closely connected magnitude representations underlie numerical and temporal processing.
    Psychological Science 12/2011; 22(12):1567-73. · 4.43 Impact Factor
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    ABSTRACT: The antisaccade task, where eye movements are made away from a target, has been used to investigate the flexibility of cognitive control of behavior. Antisaccades usually have longer saccade latencies than prosaccades, the so-called antisaccade cost. Recent studies have shown that this antisaccade cost can be modulated by event probability. This may mean that the antisaccade cost can be reduced, or even reversed, if the probability of surrounding events favors the execution of antisaccades. The probabilities of prosaccades and antisaccades were systematically manipulated by changing the proportion of a certain type of trial in an interleaved pro/antisaccades task. We aimed to disentangle the intertwined relationship between trial type probabilities and the antisaccade cost with the ultimate goal of elucidating how probabilities of trial types modulate human flexible behaviors, as well as the characteristics of such modulation effects. To this end, we examined whether implicit trial type probability can influence saccade latencies and also manipulated the difficulty of cue discriminability to see how effects of trial type probability would change when the demand on visual perceptual analysis was high or low. A mixed-effects model was applied to the analysis to dissect the factors contributing to the modulation effects of trial type probabilities. Our results suggest that the trial type probability is one robust determinant of antisaccade cost. These findings highlight the importance of implicit probability in the flexibility of cognitive control of behavior.
    Journal of Neurophysiology 05/2011; 106(2):515-26. · 3.30 Impact Factor
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    ABSTRACT: Most people find it easy to perform rhythmic movements in synchrony with music, which reflects their ability to perceive the temporal periodicity and to allocate attention in time accordingly. Musicians and non-musicians were tested in a click localization paradigm in order to investigate how grouping and metrical accents in metrical rhythms influence attention allocation, and to reveal the effect of musical expertise on such processing. We performed two experiments in which the participants were required to listen to isochronous metrical rhythms containing superimposed clicks and then to localize the click on graphical and ruler-like representations with and without grouping structure information, respectively. Both experiments revealed metrical and grouping influences on click localization. Musical expertise improved the precision of click localization, especially when the click coincided with a metrically strong beat. Critically, although all participants located the click accurately at the beginning of an intensity group, only musicians located it precisely when it coincided with a strong beat at the end of the group. Removal of the visual cue of grouping structures enhanced these effects in musicians and reduced them in non-musicians. These results indicate that musical expertise not only enhances attention to metrical accents but also heightens sensitivity to perceptual grouping.
    Experimental Brain Research 03/2011; 210(2):269-82. · 2.22 Impact Factor
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    ABSTRACT: The executive control of voluntary action involves not only choosing from a range of possible actions but also the inhibition of responses as circumstances demand. Recent studies have demonstrated that many clinical populations, such as people with attention-deficit hyperactivity disorder, exhibit difficulties in inhibitory control. One prefrontal area that has been particularly associated with inhibitory control is the pre-supplementary motor area (Pre-SMA). Here we applied non-invasive transcranial direct current stimulation (tDCS) over Pre-SMA to test its role in this behavior. tDCS allows for current to be applied in two directions to selectively excite or suppress the neural activity of Pre-SMA. Our results showed that anodal tDCS improved efficiency of inhibitory control. Conversely, cathodal tDCS showed a tendency towards impaired inhibitory control. To our knowledge, this is the first demonstration of non-invasive intervention tDCS altering subjects' inhibitory control. These results further our understanding of the neural bases of inhibitory control and suggest a possible therapeutic intervention method for clinical populations.
    NeuroImage 03/2011; 56(4):2249-57. · 6.25 Impact Factor
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    ABSTRACT: The visual system possesses a remarkable ability in learning regularities from the environment. In the case of contextual cuing, predictive visual contexts such as spatial configurations are implicitly learned, retained, and used to facilitate visual search-all without one's subjective awareness and conscious effort. Here we investigated whether implicit learning and its facilitatory effects are sensitive to the statistical property of such implicit knowledge. In other words, are highly probable events learned better than less probable ones even when such learning is implicit? We systematically varied the frequencies of context repetition to alter the degrees of learning. Our results showed that search efficiency increased consistently as contextual probabilities increased. Thus, the visual contexts, along with their probability of occurrences, were both picked up by the visual system. Furthermore, even when the total number of exposures was held constant between each probability, the highest probability still enjoyed a greater cuing effect, suggesting that the temporal aspect of implicit learning is also an important factor to consider in addition to the effect of mere frequency. Together, these findings suggest that implicit learning, although bypassing observers' conscious encoding and retrieval effort, behaves much like explicit learning in the sense that its facilitatory effect also varies as a function of its associative strengths.
    Perception 01/2011; 40(7):822-9. · 1.31 Impact Factor
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    ABSTRACT: Predictability in the visual environment provides a powerful cue for efficient processing of scenes and objects. Recently, studies have suggested that the directionality and magnitude of saccade curvature can be informative as to how the visual system processes predictive information. The present study investigated the role of the right posterior parietal cortex (rPPC) in shaping saccade curvatures in the context of predictive and non-predictive visual cues. We used an orienting paradigm that incorporated manipulation of target location predictability and delivered transcranial magnetic stimulation (TMS) over rPPC. Participants were presented with either an informative or uninformative cue to upcoming target locations. Our results showed that rPPC TMS generally increased saccade latency and saccade error rates. Intriguingly, rPPC TMS increased curvatures away from the distractor only when the target location was unpredictable and decreased saccadic errors towards the distractor. These effects on curvature and accuracy were not present when the target location was predictable. These results dissociate the strong contingency between saccade latency and saccade curvature and also indicate that rPPC plays an important role in allocating and suppressing attention to distractors when the target demands visual disambiguation. Furthermore, the present study suggests that, like the frontal eye fields, rPPC is critically involved in determining saccade curvature and the generation of saccadic behaviors under conditions of differing target predictability.
    Human Brain Mapping 01/2011; 32(11):1961-72. · 6.88 Impact Factor
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    ABSTRACT: Inhibitory control mechanisms are important in a range of behaviors to prevent execution of motor acts which, having been planned, are no longer necessary. Ready examples of this can be seen in a range of sports, such as cricket and baseball, where the choice between execution or inhibition of a bat swing must be made in a brief time interval. The role of the FEFs, an area typically described in relation to eye movement functions but also involved in visual processes, was investigated in an inhibitory control task using transcranial magnetic stimulation (TMS). A stop signal task with manual responses was used, providing measures of impulsivity and inhibitory control. TMS over FEF had no effect on response generation (impulsivity, indexed by go signal RT) but disrupted inhibitory control (indexed by stop signal RT). This is the first demonstration of a role for FEF in this type of task in normal subjects in a task which did not require eye movements and complements previous TMS findings of roles for pre-SMA and inferior frontal gyrus (IFG) in inhibitory control.
    Journal of Cognitive Neuroscience 12/2010; 22(12):2804-12. · 4.49 Impact Factor

Publication Stats

1k Citations
407.95 Total Impact Points

Institutions

  • 2005–2014
    • Academia Sinica
      • Institute of Linguistics
      T’ai-pei, Taipei, Taiwan
  • 2001–2014
    • National Yang Ming University
      • Institute of Neuroscience
      T’ai-pei, Taipei, Taiwan
  • 2010–2011
    • National Central University
      • Graduate Institute of Cognitive Neuroscience
      Taoyuan City, Taiwan, Taiwan
    • University College London
      • Institute of Cognitive Neuroscience
      London, ENG, United Kingdom
  • 2009
    • University of California, Santa Cruz
      • Department of Psychology
      Santa Cruz, CA, United States
  • 2007
    • Taipei City Hospital
      T’ai-pei, Taipei, Taiwan
  • 2006
    • Taipei Veterans General Hospital
      • Department of Medical Research and Education
      Taipei, Taipei, Taiwan
  • 1990–1991
    • University of California, Riverside
      • Department of Psychology
      Riverside, CA, United States
  • 1978
    • CSU Mentor
      Long Beach, California, United States