Thomas M Spalek

Publications of Thomas M Spalek

• LCDs are better: Psychophysical and photometric estimates of the temporal characteristics of CRT and LCD monitors.

  Authors: Hayley E P Lagroix, Matthew R Yanko, Thomas M Spalek

  Attention, perception & psychophysics. 02/2012;

  Many cognitive and perceptual phenomena, such as iconic memory and temporal integration, require brief displays. A critical requirement is that the image not remain visible after its offset. It isMany cognitive and perceptual phenomena, such as iconic memory and temporal integration, require brief displays. A critical requirement is that the image not remain visible after its offset. It is commonly believed that liquid crystal displays (LCD) are unsuitable because of their poor temporal response characteristics relative to cathode-ray-tube (CRT) screens. Remarkably, no psychophysical estimates of visible persistence are available to verify this belief. A series of experiments in which white stimuli on a black background produced discernible persistence on CRT but not on LCD screens, during both dark- and light-adapted viewing, falsified this belief. Similar estimates using black stimuli on a white background produced no visible persistence on either screen. That said, photometric measurements are available that seem to confirm the poor temporal characteristics of LCD screens, but they were obtained before recent advances in LCD technology. Using current LCD screens, we obtained photometric estimates of rise time far shorter (1-6 ms) than earlier estimates (20-150 ms), and approaching those of CRTs (<1 ms). We conclude that LCDs are preferable to CRTs when visible persistence is a concern, except when black-on-white displays are used.

• The attentional blink is not affected by backward masking of T2, T2-mask SOA, or level of T2 impoverishment.

  Authors: Ali Jannati, Thomas M Spalek, Hayley E P Lagroix, Vincent Di Lollo

  Journal of experimental psychology. Human perception and performance. 11/2011; 38(1):161-8.

  Identification of the second of two targets (T2) is impaired when presented shortly after the first (T1). This attentional blink (AB) is thought to arise from a delay in T2 processing during which T2Identification of the second of two targets (T2) is impaired when presented shortly after the first (T1). This attentional blink (AB) is thought to arise from a delay in T2 processing during which T2 is vulnerable to masking. Conventional studies have measured T2 accuracy which is constrained by the 100% ceiling. We avoided this problem by using a dynamic threshold-tracking procedure that is inherently free from ceiling constraints. In two experiments we examined how AB magnitude is affected by three masking-related factors: (a) presence/absence of T2 mask, (b) T2-mask stimulus onset asynchrony (SOA), and (c) level of T2 impoverishment (signal-to-noise ratio [SNR]). In Experiment 1, overall accuracy decreased with T2-mask SOA. The magnitude of the AB, however, was invariant with SOA and with mask presence/absence. Experiment 2 further showed that the AB was invariant with T2 SNR. The relationship among mask presence/absence, SOA, and T2 SNR and the AB is encompassed in a qualitative model.

• Perception of temporal order is impaired during the time course of the attentional blink.

  Authors: Thomas M Spalek, Hayley E P Lagroix, Matthew R Yanko, Vincent Di Lollo

  Journal of experimental psychology. Human perception and performance. 09/2011;

  Identification accuracy for the second of two target (T2) is impaired when presented shortly after the first (T1). Does this attentional blink (AB) also impair the perception of the order ofIdentification accuracy for the second of two target (T2) is impaired when presented shortly after the first (T1). Does this attentional blink (AB) also impair the perception of the order of presentation? In four experiments, three letter targets (T1, T2, T3) were inserted in a stream of digit distractors displayed in rapid serial visual presentation (RSVP), with T3 always presented directly after T2. The T1-T2 lag was varied to assess the perception of T2-T3 temporal order throughout the period of the AB. Factorial manipulation of the presence or absence of distractors before T1 and between T1 and T2 had similar effects on accuracy and on perception of temporal order. It is important to note that perception of temporal order suffered even when accuracy was unimpaired. This pattern of results is consistent with prior-entry theories of the perception of temporal order but not with episodic-integration theories. Simulations based on the Episodic Simultaneous Type, Serial Token (eSTST) model (Wyble, Bowman, & Nieuwenstein, 2009) provided excellent fits to the data except for the condition in which no distractors were presented in the RSVP stream. (PsycINFO Database Record (c) 2011 APA, all rights reserved).

• The role of observer strategy in the single-target AB paradigm.

  Authors: Hayley E P Lagroix, Thomas M Spalek, Vincent Di Lollo

  Psychonomic bulletin & review. 07/2011; 18(5):917-22.

  Identification of the second of two targets (T1, T2) inserted in a stream of distractors is impaired when presented 200-500 ms after the first (attentional blink, AB). An AB-like effect has beenIdentification of the second of two targets (T1, T2) inserted in a stream of distractors is impaired when presented 200-500 ms after the first (attentional blink, AB). An AB-like effect has been reported by Nieuwenstein, Potter, and Theeuwes, Journal of Experimental Psychology: Human Perception and Performance, 35, 159-169, (2009, Experiment 2), with a distractor stream that contained only one target and a gap just before the target. Nieuwenstein et al. hypothesized that the gap enhanced the salience of the last distractor, causing it to be processed much like T1 in conventional AB studies. This hypothesis can also account for Lag-1 sparing (enhanced target performance when presented directly after the last distractor, without an intervening gap). We propose an alternative account of the Lag-1 sparing in the single-target paradigm based on observer strategy, and test it by presenting the single-target and dual-target conditions to separate groups (Experiment 2) instead of mixed across trials (Experiment 1 and Nieuwenstein et al.'s study). The single-target condition exhibited Lag-1 sparing when it was mixed with the dual-target condition, but Lag-1 deficit when it was done in isolation. This outcome is consistent with an observer-strategy account but not with an enhanced salience account of the Lag-1 sparing effect in the single-target condition.

• On the labile memory buffer in the attentional blink: masking the T2 representation by onset transients mediates the AB.

  Authors: Ali Jannati, Thomas M Spalek, Vincent Di Lollo

  Journal of experimental psychology. Human perception and performance. 04/2011; 37(4):1182-92.

  Report of a second target (T2) is impaired when presented within 500 ms of the first (T1). This attentional blink (AB) is known to cause a delay in T2 processing during which T2 must be stored in aReport of a second target (T2) is impaired when presented within 500 ms of the first (T1). This attentional blink (AB) is known to cause a delay in T2 processing during which T2 must be stored in a labile memory buffer. We explored the buffer's characteristics using different types of masks after T2. These characteristics were inferred by determining what attributes of T2 are hindered by a given form of masking. In Experiments 1-3, trailing metacontrast and four-dot masks produced ABs of equal magnitudes, implicating the onset-transient triggered by the mask as the mechanism underlying the AB and strongly suggesting a locus in early vision. In Experiment 4, metacontrast and four-dot masks were presented in a common-onset masking (COM) paradigm in which a brief, combined display of T2 and the mask was followed by a longer display of the mask alone. COM is thought to occur late in the sequence of processing events. No AB occurred with COM, confirming the critical role of the mask's onset transients and ruling out a high-level locus for the labile memory buffer.

• Unique sudden onsets capture attention even when observers are in feature-search mode.

  Authors: Thomas M Spalek, Matthew R Yanko, Paola Poiese, Hayley E P Lagroix

  Psychological research. 03/2011; 76(1):8-19.

  Two sources of attentional capture have been proposed: stimulus-driven (exogenous) and goal-oriented (endogenous). A resolution between these modes of capture has not been straightforward. Even suchTwo sources of attentional capture have been proposed: stimulus-driven (exogenous) and goal-oriented (endogenous). A resolution between these modes of capture has not been straightforward. Even such a clearly exogenous event as the sudden onset of a stimulus can be said to capture attention endogenously if observers operate in singleton-detection mode rather than feature-search mode. In four experiments we show that a unique sudden onset captures attention even when observers are in feature-search mode. The displays were rapid serial visual presentation (RSVP) streams of differently coloured letters with the target letter defined by a specific colour. Distractors were four #s, one of the target colour, surrounding one of the non-target letters. Capture was substantially reduced when the onset of the distractor array was not unique because it was preceded by other sets of four grey # arrays in the RSVP stream. This provides unambiguous evidence that attention can be captured both exogenously and endogenously within a single task.

• Alerting enhances target identification but does not affect the magnitude of the attentional blink.

  Authors: Thomas M Spalek, Vincent Di Lollo

  Attention, perception & psychophysics. 02/2011; 73(2):405-19.

  Identification of the second of two targets is impaired when presented less than about 500 ms after the first. The magnitude of this attentional blink (AB) is known to be modulated by tonic factorsIdentification of the second of two targets is impaired when presented less than about 500 ms after the first. The magnitude of this attentional blink (AB) is known to be modulated by tonic factors (e.g., observer's state of relaxation). The present work examined the effects of a phasic change in observer's state brought about by an alerting stimulus (an aggregate of faint rings) presented in temporal proximity to either letter-target inserted in a temporal stream (RSVP) of digit distractors. In four experiments, identification accuracy of each target was substantially improved by presenting the alerting stimulus either in the target's frame or in the preceding RSVP frame. However, alerting did not modulate the magnitude of the AB. The appearance of an alerting effect on the AB in Experiment 1 was ascribed to a ceiling effect in Experiment 2. Experiment 3 ruled out endogenous temporal cueing effects; Experiment 4 examined the temporal gradient of alerting. Independence of the alerting and AB effects suggests that the alerting stimuli and the letter targets may be processed along distinct visual pathways.

• Neither backward masking of T2 nor task switching is necessary for the attentional blink.

  Authors: Ali Jannati, Thomas M Spalek, Vincent Di Lollo

  Psychonomic bulletin & review. 02/2011; 18(1):70-5.

  Identification of the second of two targets (T1, T2, inserted in a stream of distractors) is impaired when presented within 500 ms after the first (attentional blink, AB). Barring a T1-T2Identification of the second of two targets (T1, T2, inserted in a stream of distractors) is impaired when presented within 500 ms after the first (attentional blink, AB). Barring a T1-T2 task-switch, it is thought that T2 must be backward-masked to obtain an AB (Giesbrecht & Di Lollo, Journal of Experimental Psychology: Human Perception and Performance, 24, 1454-1466, 1998). We tested the hypothesis that Giesbrecht & Di Lollo's findings were vitiated by ceiling constraints arising from either response scale (experiment 1) or data limitations (experiment 2). In experiment 1, digit-distractors were replaced with pseudoletters to increase task difficulty, bringing performance below ceiling. An AB occurred without backward masking of T2. In experiment 2, a ceiling-free procedure estimated the number of noise dots needed for 80% T2 identification. An AB was revealed: fewer noise dots were required during the AB period than outside it. Both outcomes confirm that an AB can be obtained without either masking of T2 or task switching.

• On the role of intervening distractors in the attentional blink.

  Authors: Benoit Brisson, Thomas M Spalek, Vincent Di Lollo

  Attention, perception & psychophysics. 01/2011; 73(1):42-52.

  The attentional blink (AB) refers to the decline in accurate report for a second target (T2) when presented within about 500 ms of a first target (T1) embedded in a rapid serial visual presentationThe attentional blink (AB) refers to the decline in accurate report for a second target (T2) when presented within about 500 ms of a first target (T1) embedded in a rapid serial visual presentation stream of distractors. It is debated whether the distractors presented shortly after T1 cause the AB directly, as is proposed by distractor-based models, or can modulate its amplitude only indirectly by increasing T1 difficulty, as is proposed by capacity-based models. To investigate this issue, an intervening distractor was presented at lag 1 (T1 + 1), at lag 2 (T1 + 2), or at neither of these two lags (no distractor). T2 was presented at either lag 3 or 9. An AB was observed even in the absence of intervening distractors, indicating that distractors are not necessary to produce an AB. Nonetheless, the T1 + 2 distractor did modulate the AB directly, without influencing T1 performance. Neither theory can fully account for the results but can do so given some modifications.

• Backward masking during rapid serial visual presentation affects the amplitude but not the latency of the P3 event-related potential.

  Authors: Benoit Brisson, Nicolas Robitaille, Alexandrine Deland-Bélanger, Thomas M Spalek, Vincent Di Lollo, Pierre Jolicoeur

  Psychophysiology. 03/2010; 47(5):942-8.

  Masking of the first target in the attentional blink (AB) paradigm increases the magnitude of the AB relative to when the first target is not masked. We examined the underlying causes of this effectMasking of the first target in the attentional blink (AB) paradigm increases the magnitude of the AB relative to when the first target is not masked. We examined the underlying causes of this effect in an experiment in which a single target was presented in a rapid visual serial presentation stream. The P3 to the target was isolated by subtracting infrequent target category trials from frequent target category trials. The item immediately trailing the target (i.e., the mask) was present in the masked condition and replaced by a blank screen in the not-masked condition, reproducing conditions known to modulate the AB. Masking the target significantly reduced the amplitude of the target-locked P3 but had no effect on P3 latency. Results are discussed in relation to previous findings in the AB literature.

• Flicker is a primitive visual attribute in visual search.

  Authors: Thomas M Spalek, Jun-Ichiro Kawahara, Vincent Di Lollo

  Canadian journal of experimental psychology = Revue canadienne de psychologie expérimentale. 12/2009; 63(4):319-22.

  At the earliest processing stages, visual stimuli are decomposed by a set of filters tuned to specific values of such attributes as colour, orientation, and motion. These filters have beenAt the earliest processing stages, visual stimuli are decomposed by a set of filters tuned to specific values of such attributes as colour, orientation, and motion. These filters have been characterised both neurophysiologically and behaviourally. The single exception is the attribute of flicker that has been characterised neurophysiologically but not behaviourally. Using a visual search paradigm, the authors provide the first behavioural demonstration that flicker is indeed a primitive attribute used by the visual system in stimulus encoding. Consistent with the temporal contrast-sensitivity function, sensitivity to flicker was highest at about 10 Hz and decreased as the flicker rate was either increased or decreased. (PsycINFO Database Record (c) 2009 APA, all rights reserved).

• Turning the process-dissociation procedure inside-out: A new technique for understanding the relation between conscious and unconscious influences.

  Authors: Steve Joordens, Daryl E Wilson, Thomas M Spalek, Dwayne E Paré

  Consciousness and cognition. 10/2009;

  While there is now general agreement that memory gives rise to both conscious and unconscious influences, there remains disagreement concerning the process architecture underlying these distinctWhile there is now general agreement that memory gives rise to both conscious and unconscious influences, there remains disagreement concerning the process architecture underlying these distinct influences. Do they arise from independent underlying systems (e.g., Jacoby, 1991) or from systems that are interactive (e.g., Joordens & Merikle, 1993)? In the current paper we present a novel "inside-out" technique that can be used with the process-dissociation paradigm to arrive at more concrete conclusions concerning this central question and demonstrate this technique via a meta-analysis of currently published findings. Our results suggest that the data presented in these studies vary in ways most consistent with the assumption that conscious and unconscious influences behave independently.

• Are spatial selection and identity extraction separable when attention is controlled endogenously?

  Authors: Shahab Ghorashi, Thomas M Spalek, James T Enns, Vincent Di Lollo

  Attention, perception & psychophysics. 09/2009; 71(6):1233-40.

  Visual search for a target involves two processes: spatial selection and identity extraction. Ghorashi, Enns, and Di Lollo (2008) found these processes to be independent and surmised that they wereVisual search for a target involves two processes: spatial selection and identity extraction. Ghorashi, Enns, and Di Lollo (2008) found these processes to be independent and surmised that they were carried out along distinct visual pathways: dorsal and ventral, respectively. The two experiments that are described in the present article evaluated this hypothesis. Attentional-blink methodology was combined with voluntary spatial cuing in a visual search task: Intertarget lag was used to manipulate identity extraction; predictive cues were used to signal target locations. Central digit cues in Experiment 1 required participants to identify digits before voluntarily directing attention to a corresponding location, whereas flashed dots in Experiment 2 (indicating an opposite location) required attentional redeployment without prior cue identification. Consistent with the dual-pathway hypothesis, cuing was impaired only when the first target and the number cue competed for ventral-pathway mechanisms. Collectively, the results support the dual-pathway account of the separability of spatial selection and identity extraction.

• Spatial cuing does not affect the magnitude of the attentional blink.

  Authors: Shahab Ghorashi, James T Enns, Thomas M Spalek, Vincent Di Lollo

  Attention, perception & psychophysics. 08/2009; 71(5):989-93.

  Identification of the second of two targets is impaired when the second target is presented less than about 500 msec after the first. Nieuwenstein, Chun, van der Lubbe, and Hooge (2005, Experiment 4)Identification of the second of two targets is impaired when the second target is presented less than about 500 msec after the first. Nieuwenstein, Chun, van der Lubbe, and Hooge (2005, Experiment 4) reported that the magnitude of this attentional blink (AB) is reduced when the location of the second target is precued. Here we show how that finding resulted from an artifact brought about by a ceiling imposed by data limitation. Instead of using an accuracy measure, the present work used a dynamic threshold-tracking procedure that was not constrained by a performance ceiling. The results show that, when the ceiling is removed, spatial cuing does not affect and is not affected by the AB. These results are consistent with the hypothesis that cue localization and target identification may take place along separate (dorsal and ventral) visual pathways.

• The attentional blink: Increasing target salience provides no evidence for resource depletion. A commentary on Dux, Asplund, and Marois (2008).

  Authors: Christian N L Olivers, Thomas M Spalek, Jun-Ichiro Kawahara, Vincent Di Lollo

  Psychonomic bulletin & review. 03/2009; 16(1):214-8.

  The authors have argued elsewhere that the attentional blink (AB; i.e., reduced target detection shortly after presentation of an earlier target) arises from blocked or disrupted perceptual input inThe authors have argued elsewhere that the attentional blink (AB; i.e., reduced target detection shortly after presentation of an earlier target) arises from blocked or disrupted perceptual input in response to distractors presented between the targets. When targets replace the intervening distractors, so that three targets (T1, T2, and T3) are presented sequentially, performance on T2 and T3 improves. Dux, Asplund, and Marois (2008) argued that T3 performance improves at the expense of T1, and thus provides evidence for resource depletion. They showed that when T1 is made more salient (and presumably draws more resources), an AB for T3 appears to reemerge. These findings can be better explained, however, by (1) the relationship between T1 and T2 (not T1 and T3) and (2) differential salience for T3 in the long-lag condition of Dux et al.'s study. In conclusion, the Dux et al. study does not present a severe challenge to input control theories of the AB.

• Attentional capture by a salient distractor in visual search: The effect of target-distractor similarity.

  Authors: Paola Poiese, Thomas M Spalek, Vincent Di Lollo

  Canadian journal of experimental psychology = Revue canadienne de psychologie expérimentale. 01/2009; 62(4):233-6.

  Models of attentional selection are based on either stimulus-driven or goal-directed processes. Support for the latter comes from a study showing that a salient singleton in a search display can beModels of attentional selection are based on either stimulus-driven or goal-directed processes. Support for the latter comes from a study showing that a salient singleton in a search display can be ignored when the target has a different defining feature (Kumada, 1999). We show that this finding holds only when the target and the nonsalient distractors are highly dissimilar from one another. When the target and the distractors are made more similar, whilst ensuring that the target still pops out of the display, the salient distractor can no longer be ignored. This outcome is consistent with predictions from stimulus-driven accounts. (PsycINFO Database Record (c) 2008 APA, all rights reserved).

• A direct assessment of the role of expectation in inhibition of return.

  Authors: Thomas M Spalek

  Psychological science : a journal of the American Psychological Society / APS. 10/2007; 18(9):783-7.

  An object hidden among distractors can be found more efficiently if previously searched locations are not reinspected. The inhibition-of-return (IOR) phenomenon indexes the tendency to avoidAn object hidden among distractors can be found more efficiently if previously searched locations are not reinspected. The inhibition-of-return (IOR) phenomenon indexes the tendency to avoid reinspections. Two accounts of IOR, that it is due to inhibition and that it is due to expectation, are generally regarded as incompatible. The relevant evidence to date, however, has been indirect: Inhibition or expectation has been inferred from response times or similar indirect measures. This article reports the first direct measure of IOR, obtained by asking observers to predict the location of the next target in a display containing eight possible locations on an imaginary circle. On any given trial, the previously cued location was chosen less frequently (impairment)--and the opposite location was chosen more frequently (facilitation)--than chance (choice of all other locations was at chance). The impairment is consistent with both inhibition and expectation accounts; the facilitation is consistent only with expectation accounts. This work also shows that inhibition and expectation are not necessarily incompatible: Implementing expectations may entail inhibiting previously cued locations.

• The time required for perceptual (nonmotoric) processing in IOR.

  Authors: Thomas M Spalek, Vincent Di Lollo

  Psychonomic bulletin & review. 05/2007; 14(2):327-31.

  In an inhibition of return (IOR) paradigm, we used a threshold-tracking procedure combined with backward masking to measure the speed of perceptual processing in IOR independent of motoric factors.In an inhibition of return (IOR) paradigm, we used a threshold-tracking procedure combined with backward masking to measure the speed of perceptual processing in IOR independent of motoric factors. Instead of the conventional reaction time measure, this procedure yielded the critical exposure duration (DURc) that is required in order for a target to be identified reliably before the onset of a trailing mask. In Experiment 1, the facilitation effects conventionally found at short cue-target onset asynchrony (CTOA) were evidenced by shorter values of DURc at cued relative to uncued locations. Conversely, the retardation effects conventionally found at long CTOA were evidenced by correspondingly longer values of DURc. In Experiment 2, the DURc results strongly suggest that the directional reading bias previously observed in IOR studies is due, at least in part, to perceptual rather than motoric factors.

• Selective attention versus selection for action: negative priming is not the result of distractors being unattended.

  Authors: Steve Joordens, Itanni Betancourt, Thomas M Spalek

  Perception & psychophysics. 08/2006; 68(6):890-6.

  Using a novel referent size-selection task, MacDonald, Joordens, and Seergobin (1999; MacDonald & Joordens, 2000) found that negative priming persisted even when participants were encouraged toUsing a novel referent size-selection task, MacDonald, Joordens, and Seergobin (1999; MacDonald & Joordens, 2000) found that negative priming persisted even when participants were encouraged to attend to distractors before selectively responding to targets. This finding suggested that negative priming is not caused by processes that operate on stimuli that are to be ignored in the traditional selective attention sense. Mackintosh, Mathews, and Holden's (2002) attempt to replicate the MacDonald et al. study resulted in the discovery of possible artifacts in the referent size-selection task, thereby making the implications with respect to the role of attention less clear. In the present study, we describe a different method for directing attention to distractors in a negative priming context, one that does not suffer from the same potential artifacts as the referent size-selection task. Our results are consistent with those found by MacDonald et al., in that negative priming persisted even when participants were explicitly encouraged to attend to distractors. Implications are discussed in the context of the related concepts of selective attention (e.g., Broadbent, 1965) versus selection for action (e.g., Allport, 1987).

• Attentional blink and attentional capture: endogenous versus exogenous control over paying attention to two important events in close succession.

  Authors: Thomas M Spalek, Laura J Falcon, Vincent Di Lollo

  Perception & psychophysics. 06/2006; 68(4):674-84.

  Identification of the second of two targets is impaired if it is presented less than about 500 msec after the first This attentional blink (AB) occurs under dual-task conditions in which observersIdentification of the second of two targets is impaired if it is presented less than about 500 msec after the first This attentional blink (AB) occurs under dual-task conditions in which observers are required to report both targets. AB magnitude has been estimated by subtracting the accuracy scores in the dual task from the corresponding scores in a single task in which observers are instructed to ignore the first target. Experiment 1 showed this procedure to be inappropriate, because the first target cannot be ignored. The remaining three experiments elaborated on this finding andrevealed separate endogenous and exogenous sources of the second-target deficit. A parallel was drawn between the AB deficit and the deficit observed in attentional capture. Both types of deficit can be explained on the basis of a hybrid input-filtering model in which endogenous and exogenous factors are subserved by different pathways.