Brad Wyble - Academia.edu (original) (raw)

Papers by Brad Wyble

There is evidence that conscious perception during the attentional blink is all-or-none, which co... more There is evidence that conscious perception during the attentional blink is all-or-none, which contrasts with the finding of a continuum of perceptual strength in masking experiments. This seems to reveal the underlying representation of strength that can be found in the brain in the absence of attentional enhancement. We provide electrophysiological support for this all-or-none theory. Then, using principles from the ST 2 model of temporal attention and working memory, we show how this all-or-none pattern can be explained by the delayed target consolidation that is known to arise during the attentional blink.

Temporal feature binding in vision refers to the process by which features of objects presented o... more Temporal feature binding in vision refers to the process by which features of objects presented one after the other at the same spatial location are correctly bound together. In this paper, we describe a computational model of putative neural mechanisms that would produce this behaviour. These simulations highlight the role of transient attentional enhancement in mediating the temporal binding of features into working memory. This model builds upon previous approaches, and explains a range of behavioural findings relating to the patterns of illusory conjunctions observed in experiments. Further, it provides a parsimonious account of a counter-intuitive pattern of reaction time data.

Journal of Experimental Psychology-human Perception and Performance, 2011

In whole report, a sentence presented sequentially at the rate of about 10 words/s can be recalle... more In whole report, a sentence presented sequentially at the rate of about 10 words/s can be recalled accurately, whereas if the task is to report only two target words (e.g., red words), the second target suffers an attentional blink if it appears shortly after the first target. If these two tasks are carried out simultaneously, is there an attentional blink, and does it affect both tasks? Here, sentence report was combined with report of two target words (Experiments 1 and 2) or two inserted target digits, Arabic numerals or word digits (Experiments 3 and 4). When participants reported only the targets an attentional blink was always observed. When they reported both the sentence and targets, sentence report was quite accurate but there was an attentional blink in picking out the targets when they were part of the sentence. When targets were extra digits inserted in the sentence there was no blink when viewers also reported the sentence. These results challenge some theories of the attentional blink: Blinks result from online selection, not perception or memory.

Neuroscience and Biobehavioral Reviews, 2010

A wealth of neurophysiological data has demonstrated that visual attention can selectively enhanc... more A wealth of neurophysiological data has demonstrated that visual attention can selectively enhance target representations early in the visual processing pathway. In addition, behavioural evidence tells us that the extent to which irrelevant items interfere with target processing depends on their featural similarity to the target. In this context, how does target discriminability influence temporal selection? We present results from an electrophysiology study that addresses this question by investigating the time course of the neural processes involved in target selection as target distinctiveness is varied. The results suggest that, in line with previous findings, making discrimination harder reduces the accuracy of target identification. We find that there are significant differences in the perceptual processing of the target in the two conditions, as indexed by early visual ERPs and the P3 ERP. We ground this and previous empirical evidence within a theoretical framework for understanding the mechanism of attentional selection represented in the ST 2 model, a neural network model of temporal attention and working memory. By simulating both experimental conditions, we show that the model provides a convincing explanation of the pattern of experimental results, in addition to informing questions about the nature and time course of attentional selection.

The attentional blink (AB) refers to the finding that observers often miss the second of two mask... more The attentional blink (AB) refers to the finding that observers often miss the second of two masked visual targets (T1 and T2, e.g., letters) appearing within 200-500 ms. Although the presence of a T1 mask is thought to be required for this effect, we recently found that an AB deficit can be observed even in the absence of a T1 mask if T2 is shown very briefly and followed by a pattern mask (M. R. Nieuwenstein, M. C. Potter, & J. Theeuwes, 2009). Using such a sensitive T2 task, the present study sought to determine the minimum requirements for eliciting an AB deficit. To this end, we examined if the occurrence of an AB depends on T1 exposure duration, the requirement to perform a task for T1, and awareness of T1. The results showed that an AB deficit occurs regardless of the presentation duration of T1, and regardless of whether there is a T1 task. A boundary condition for the occurrence of an AB was found in conscious awareness of T1. With a nearthreshold detection task for T1, attention blinked when T1 was seen, but not when T1 was missed. Accordingly, we conclude that the minimum requirement for an AB deficit is T1 awareness. * ARVO T1 was not masked and T2 was presented for 100 ms, whereas a 100-ms T2 did show an AB deficit when T1 was masked. However, when T2 was presented for only 58 ms, the results for the Unmasked T1 condition showed a substantial attentional blink effect for T2.

PLOS Computational Biology, 2009

What role does attention play in ensuring the temporal precision of visual perception? Behavioura... more What role does attention play in ensuring the temporal precision of visual perception? Behavioural studies have investigated feature selection and binding in time using fleeting sequences of stimuli in the Rapid Serial Visual Presentation (RSVP) paradigm, and found that temporal accuracy is reduced when attentional control is diminished. To reduce the efficacy of attentional deployment, these studies have employed the Attentional Blink (AB) phenomenon. In this article, we use electroencephalography (EEG) to directly investigate the temporal dynamics of conscious perception. Specifically, employing a combination of experimental analysis and neural network modelling, we test the hypothesis that the availability of attention reduces temporal jitter in the latency between a target's visual onset and its consolidation into working memory. We perform time-frequency analysis on data from an AB study to compare the EEG trials underlying the P3 ERPs (Event-related Potential) evoked by targets seen outside vs. inside the AB time window. We find visual differences in phase-sorted ERPimages and statistical differences in the variance of the P3 phase distributions. These results argue for increased variation in the latency of conscious perception during the AB. This experimental analysis is complemented by a theoretical exploration of temporal attention and target processing. Using activation traces from the Neural-ST 2 model, we generate virtual ERPs and virtual ERPimages. These are compared to their human counterparts to propose an explanation of how target consolidation in the context of the AB influences the temporal variability of selective attention. The AB provides us with a suitable phenomenon with which to investigate the interplay between attention and perception. The combination of experimental and theoretical elucidation in this article contributes to converging evidence for the notion that the AB reflects a reduction in the temporal acuity of selective attention and the timeliness of perception.

Journal of Experimental Psychology-human Perception and Performance, 2009

Transient attention to a visually salient cue enhances processing of a subsequent target in the s... more Transient attention to a visually salient cue enhances processing of a subsequent target in the same spatial location between 50 to 150 ms after cue onset . Do stimuli from a categorically defined target set, such as letters or digits, also generate transient attention? Participants reported digit targets among keyboard symbols in a changing array of 8 items. When one target preceded a second target in the same location at an SOA of 107 ms (but not 213 ms), the second target was reported more often than in a condition in which there was no leading target. When the two targets were at different locations, report of the second target was impaired. With both letters and digits as targets, the enhancement effect was shown not to be due to category priming. Critically, the attentional benefit was present whether or not participants reported the leading target. Transient attention, contingent attentional capture, popout, and lag 1 sparing in the attentional blink may involve a common mechanism for orienting processing resources towards salient and task relevant stimuli.

To explore the degree which attentional set in one task interferes with performance in a secondar... more To explore the degree which attentional set in one task interferes with performance in a secondary task, we have developed a prototype SRRI test system. This comprises a central task involving driving through a virtual maze and the presentation of an intermittent stream of competing stimuli of varying levels of salience. Centrally presented arrows are followed in the driving task and the stream of competing stimuli is presented via a head mounted display. The colour relationship between the central arrows and stimuli in the competing stream is varied. How this "task prescribed" colour relationship impinges upon attentional capture by stimuli in the competing stream is investigated. This experiment has revealed no discernible carryover effect of attentional set from one task to the other in either accuracy or reaction time for detecting the targets in the stream. Thus, the attention system seems to be adept at allocating feature based attention in a way that does not spontaneously migrate from one task to another.

There has been considerable recent interest in the identification of neural correlates of the Att... more There has been considerable recent interest in the identification of neural correlates of the Attentional Blink (AB), and the development of neurally explicit computational models. A prominent example is the Simultaneous Type Serial Token (ST 2 ) model, which suggests that when the visual system detects a task-relevant item, a spatially specific Transient Attentional Enhancement (TAE), called the blaster, is triggered. This paper reports on our investigations into EEG activity during the AB, and a hypothesized correlation between the blaster and the N2pc ERP component. Specifically, we demonstrate that the temporal firing pattern of the blaster in the model matches the N2pc component in human ERP recordings, for targets that are seen and missed inside and outside the attentional blink window. Such a correlation between a computational account of the AB and ERP data provides useful insights into the processes underlying selectivity in temporal attention.

PLOS One, 2010

Background: Most people show a remarkable deficit in reporting the second of two targets (T2) whe... more Background: Most people show a remarkable deficit in reporting the second of two targets (T2) when presented 200-500 ms after the first (T1), reflecting an 'attentional blink' (AB). However, there are large individual differences in the magnitude of the effect, with some people, referred to as 'non-blinkers', showing no such attentional restrictions.

Journal of Experimental Psychology-human Perception and Performance, 2010

A pictured object can be readily detected in an RSVP sequence when the target is specified by a s... more A pictured object can be readily detected in an RSVP sequence when the target is specified by a superordinate category name such as animal or vehicle. Are category features the initial basis for detection, with identification of the specific object occurring in a second stage , or is identification of the object the basis for detection? When two targets in the same superordinate category are presented successively (lag 1), only the identification-first hypothesis predicts lag 1 sparing of the second target. The results of two experiments with novel pictures and a wide range of categories supported the identification-first hypothesis and a transient-attention model of lag 1 sparing and the attentional blink ).

Journal of Vision, 2010

Potter, Nieuwenstein, & Strohminger (2008) found that there was an attentional blink for repo... more Potter, Nieuwenstein, & Strohminger (2008) found that there was an attentional blink for report of the second of two red (or uppercase) words at a short SOA, in an RSVP sentence presented for 93 ms per word. If participants simply reported the whole sentence without looking for ...

This paper illustrates a way for applying formal methods techniques to specifying and verifying n... more This paper illustrates a way for applying formal methods techniques to specifying and verifying neural networks, with applications in the area of neural network based controllers. Formal methods have some of the characteristics of symbolic models. We describe a communicating automata model of neural networks, where the standard Backpropagation (BP) algorithm is applied. Then we undertake a verification of this model using the model checker Uppaal , in order to predict the performance of the learning process. We discuss broad issues of integrating symbolic techniques with complex neural systems. We also argue that symbolic verifications may give theoretically well-founded ways to evaluate and justify neural learning systems.

Psychological Review, 2007

A detailed description of the simultaneous type, serial token (ST 2 ) model is presented. ST 2 is... more A detailed description of the simultaneous type, serial token (ST 2 ) model is presented. ST 2 is a model of temporal attention and working memory that encapsulates 5 principles: (a) M. M. Chun and M. C. Potter's (1995) 2-stage model, (b) a Stage 1 salience filter, (c) N. G. types-tokens distinction, (d) a transient attentional enhancement, and (e) a mechanism for associating types with tokens called the binding pool. The authors instantiate this theoretical position in a connectionist implementation, called neural-ST 2 , which they illustrate by modeling temporal attention results focused on the attentional blink (AB). They demonstrate that the ST 2 model explains a spectrum of AB findings. Furthermore, they highlight a number of new temporal attention predictions arising from the ST 2 theory, which are tested in a series of behavioral experiments. Finally, the authors review major AB models and theories and compare them with ST 2 . for discussions and input that have contributed to the development of the ST 2 model.

Journal of Vision, 2010

Abstract In a real-world context, brief glimpses of moving forms, especially people, are both pre... more Abstract In a real-world context, brief glimpses of moving forms, especially people, are both prevalent and salient. Yet in studies of search and selective attention, targets are typically static stimuli, such as characters, words, or pictures. In the present experiments, targets were briefly presented point-light walkers (PLWs), each consisting of a coherent set of moving dots that outline a person carrying out one of four actions (Serre & Giese 2007). The attentional blink (AB) is a deficit in reporting the second of two targets with an SOA of ...

Journal of Vision, 2010

A wealth of neurophysiological data has demonstrated that visual attention can selectively enhanc... more A wealth of neurophysiological data has demonstrated that visual attention can selectively enhance target representations early in the visual processing pathway. In addition, behavioural evidence tells us that the extent to which irrelevant items interfere with target processing depends on their featural similarity to the target. In this context, how does target discriminability influence temporal selection? We present results from an electrophysiology study that addresses this question by investigating the time course of the neural processes involved in target selection as target distinctiveness is varied. The results suggest that, in line with previous findings, making discrimination harder reduces the accuracy of target identification. We find that there are significant differences in the perceptual processing of the target in the two conditions, as indexed by early visual ERPs and the P3 ERP. We ground this and previous empirical evidence within a theoretical framework for understanding the mechanism of attentional selection represented in the ST 2 model, a neural network model of temporal attention and working memory. By simulating both experimental conditions, we show that the model provides a convincing explanation of the pattern of experimental results, in addition to informing questions about the nature and time course of attentional selection.

Journal of Vision, 2010

... Brad Wyble bw5{at}kent ... Abstract. It has recently been disputed whether working memory has... more ... Brad Wyble bw5{at}kent ... Abstract. It has recently been disputed whether working memory has a fixed capacity of 4 objects. Alvarez & Cavanagh (2004), for example, demonstrate that complex items appear to consume more resources than simple ones, reducing storage capacity. ...

This paper explores the feasibility of using EEG in the context of Stimulus Rich Reactive Interfa... more This paper explores the feasibility of using EEG in the context of Stimulus Rich Reactive Interfaces (SRRI's), as a source of feedback on the cognitive state of the user. We have run experiments to evaluate the utility of two potential EEG measures of whether a stimulus has been perceived: 1) reduced EEG power in the alpha band at posterior brain areas and 2) a P3-like positive deflection over parietal areas. Such measures would enable re-presentation of a critical stimulus that has been missed.

There is evidence that conscious perception during the attentional blink is all-or-none, which co... more There is evidence that conscious perception during the attentional blink is all-or-none, which contrasts with the finding of a continuum of perceptual strength in masking experiments. This seems to reveal the underlying representation of strength that can be found in the brain in the absence of attentional enhancement. We provide electrophysiological support for this all-or-none theory. Then, using principles from the ST 2 model of temporal attention and working memory, we show how this all-or-none pattern can be explained by the delayed target consolidation that is known to arise during the attentional blink.

Temporal feature binding in vision refers to the process by which features of objects presented o... more Temporal feature binding in vision refers to the process by which features of objects presented one after the other at the same spatial location are correctly bound together. In this paper, we describe a computational model of putative neural mechanisms that would produce this behaviour. These simulations highlight the role of transient attentional enhancement in mediating the temporal binding of features into working memory. This model builds upon previous approaches, and explains a range of behavioural findings relating to the patterns of illusory conjunctions observed in experiments. Further, it provides a parsimonious account of a counter-intuitive pattern of reaction time data.

Journal of Experimental Psychology-human Perception and Performance, 2011

In whole report, a sentence presented sequentially at the rate of about 10 words/s can be recalle... more In whole report, a sentence presented sequentially at the rate of about 10 words/s can be recalled accurately, whereas if the task is to report only two target words (e.g., red words), the second target suffers an attentional blink if it appears shortly after the first target. If these two tasks are carried out simultaneously, is there an attentional blink, and does it affect both tasks? Here, sentence report was combined with report of two target words (Experiments 1 and 2) or two inserted target digits, Arabic numerals or word digits (Experiments 3 and 4). When participants reported only the targets an attentional blink was always observed. When they reported both the sentence and targets, sentence report was quite accurate but there was an attentional blink in picking out the targets when they were part of the sentence. When targets were extra digits inserted in the sentence there was no blink when viewers also reported the sentence. These results challenge some theories of the attentional blink: Blinks result from online selection, not perception or memory.

Neuroscience and Biobehavioral Reviews, 2010

A wealth of neurophysiological data has demonstrated that visual attention can selectively enhanc... more A wealth of neurophysiological data has demonstrated that visual attention can selectively enhance target representations early in the visual processing pathway. In addition, behavioural evidence tells us that the extent to which irrelevant items interfere with target processing depends on their featural similarity to the target. In this context, how does target discriminability influence temporal selection? We present results from an electrophysiology study that addresses this question by investigating the time course of the neural processes involved in target selection as target distinctiveness is varied. The results suggest that, in line with previous findings, making discrimination harder reduces the accuracy of target identification. We find that there are significant differences in the perceptual processing of the target in the two conditions, as indexed by early visual ERPs and the P3 ERP. We ground this and previous empirical evidence within a theoretical framework for understanding the mechanism of attentional selection represented in the ST 2 model, a neural network model of temporal attention and working memory. By simulating both experimental conditions, we show that the model provides a convincing explanation of the pattern of experimental results, in addition to informing questions about the nature and time course of attentional selection.

The attentional blink (AB) refers to the finding that observers often miss the second of two mask... more The attentional blink (AB) refers to the finding that observers often miss the second of two masked visual targets (T1 and T2, e.g., letters) appearing within 200-500 ms. Although the presence of a T1 mask is thought to be required for this effect, we recently found that an AB deficit can be observed even in the absence of a T1 mask if T2 is shown very briefly and followed by a pattern mask (M. R. Nieuwenstein, M. C. Potter, & J. Theeuwes, 2009). Using such a sensitive T2 task, the present study sought to determine the minimum requirements for eliciting an AB deficit. To this end, we examined if the occurrence of an AB depends on T1 exposure duration, the requirement to perform a task for T1, and awareness of T1. The results showed that an AB deficit occurs regardless of the presentation duration of T1, and regardless of whether there is a T1 task. A boundary condition for the occurrence of an AB was found in conscious awareness of T1. With a nearthreshold detection task for T1, attention blinked when T1 was seen, but not when T1 was missed. Accordingly, we conclude that the minimum requirement for an AB deficit is T1 awareness. * ARVO T1 was not masked and T2 was presented for 100 ms, whereas a 100-ms T2 did show an AB deficit when T1 was masked. However, when T2 was presented for only 58 ms, the results for the Unmasked T1 condition showed a substantial attentional blink effect for T2.

PLOS Computational Biology, 2009

What role does attention play in ensuring the temporal precision of visual perception? Behavioura... more What role does attention play in ensuring the temporal precision of visual perception? Behavioural studies have investigated feature selection and binding in time using fleeting sequences of stimuli in the Rapid Serial Visual Presentation (RSVP) paradigm, and found that temporal accuracy is reduced when attentional control is diminished. To reduce the efficacy of attentional deployment, these studies have employed the Attentional Blink (AB) phenomenon. In this article, we use electroencephalography (EEG) to directly investigate the temporal dynamics of conscious perception. Specifically, employing a combination of experimental analysis and neural network modelling, we test the hypothesis that the availability of attention reduces temporal jitter in the latency between a target's visual onset and its consolidation into working memory. We perform time-frequency analysis on data from an AB study to compare the EEG trials underlying the P3 ERPs (Event-related Potential) evoked by targets seen outside vs. inside the AB time window. We find visual differences in phase-sorted ERPimages and statistical differences in the variance of the P3 phase distributions. These results argue for increased variation in the latency of conscious perception during the AB. This experimental analysis is complemented by a theoretical exploration of temporal attention and target processing. Using activation traces from the Neural-ST 2 model, we generate virtual ERPs and virtual ERPimages. These are compared to their human counterparts to propose an explanation of how target consolidation in the context of the AB influences the temporal variability of selective attention. The AB provides us with a suitable phenomenon with which to investigate the interplay between attention and perception. The combination of experimental and theoretical elucidation in this article contributes to converging evidence for the notion that the AB reflects a reduction in the temporal acuity of selective attention and the timeliness of perception.

Journal of Experimental Psychology-human Perception and Performance, 2009

Transient attention to a visually salient cue enhances processing of a subsequent target in the s... more Transient attention to a visually salient cue enhances processing of a subsequent target in the same spatial location between 50 to 150 ms after cue onset . Do stimuli from a categorically defined target set, such as letters or digits, also generate transient attention? Participants reported digit targets among keyboard symbols in a changing array of 8 items. When one target preceded a second target in the same location at an SOA of 107 ms (but not 213 ms), the second target was reported more often than in a condition in which there was no leading target. When the two targets were at different locations, report of the second target was impaired. With both letters and digits as targets, the enhancement effect was shown not to be due to category priming. Critically, the attentional benefit was present whether or not participants reported the leading target. Transient attention, contingent attentional capture, popout, and lag 1 sparing in the attentional blink may involve a common mechanism for orienting processing resources towards salient and task relevant stimuli.

To explore the degree which attentional set in one task interferes with performance in a secondar... more To explore the degree which attentional set in one task interferes with performance in a secondary task, we have developed a prototype SRRI test system. This comprises a central task involving driving through a virtual maze and the presentation of an intermittent stream of competing stimuli of varying levels of salience. Centrally presented arrows are followed in the driving task and the stream of competing stimuli is presented via a head mounted display. The colour relationship between the central arrows and stimuli in the competing stream is varied. How this "task prescribed" colour relationship impinges upon attentional capture by stimuli in the competing stream is investigated. This experiment has revealed no discernible carryover effect of attentional set from one task to the other in either accuracy or reaction time for detecting the targets in the stream. Thus, the attention system seems to be adept at allocating feature based attention in a way that does not spontaneously migrate from one task to another.

There has been considerable recent interest in the identification of neural correlates of the Att... more There has been considerable recent interest in the identification of neural correlates of the Attentional Blink (AB), and the development of neurally explicit computational models. A prominent example is the Simultaneous Type Serial Token (ST 2 ) model, which suggests that when the visual system detects a task-relevant item, a spatially specific Transient Attentional Enhancement (TAE), called the blaster, is triggered. This paper reports on our investigations into EEG activity during the AB, and a hypothesized correlation between the blaster and the N2pc ERP component. Specifically, we demonstrate that the temporal firing pattern of the blaster in the model matches the N2pc component in human ERP recordings, for targets that are seen and missed inside and outside the attentional blink window. Such a correlation between a computational account of the AB and ERP data provides useful insights into the processes underlying selectivity in temporal attention.

PLOS One, 2010

Background: Most people show a remarkable deficit in reporting the second of two targets (T2) whe... more Background: Most people show a remarkable deficit in reporting the second of two targets (T2) when presented 200-500 ms after the first (T1), reflecting an 'attentional blink' (AB). However, there are large individual differences in the magnitude of the effect, with some people, referred to as 'non-blinkers', showing no such attentional restrictions.

Journal of Experimental Psychology-human Perception and Performance, 2010

A pictured object can be readily detected in an RSVP sequence when the target is specified by a s... more A pictured object can be readily detected in an RSVP sequence when the target is specified by a superordinate category name such as animal or vehicle. Are category features the initial basis for detection, with identification of the specific object occurring in a second stage , or is identification of the object the basis for detection? When two targets in the same superordinate category are presented successively (lag 1), only the identification-first hypothesis predicts lag 1 sparing of the second target. The results of two experiments with novel pictures and a wide range of categories supported the identification-first hypothesis and a transient-attention model of lag 1 sparing and the attentional blink ).

Journal of Vision, 2010

Potter, Nieuwenstein, & Strohminger (2008) found that there was an attentional blink for repo... more Potter, Nieuwenstein, & Strohminger (2008) found that there was an attentional blink for report of the second of two red (or uppercase) words at a short SOA, in an RSVP sentence presented for 93 ms per word. If participants simply reported the whole sentence without looking for ...

This paper illustrates a way for applying formal methods techniques to specifying and verifying n... more This paper illustrates a way for applying formal methods techniques to specifying and verifying neural networks, with applications in the area of neural network based controllers. Formal methods have some of the characteristics of symbolic models. We describe a communicating automata model of neural networks, where the standard Backpropagation (BP) algorithm is applied. Then we undertake a verification of this model using the model checker Uppaal , in order to predict the performance of the learning process. We discuss broad issues of integrating symbolic techniques with complex neural systems. We also argue that symbolic verifications may give theoretically well-founded ways to evaluate and justify neural learning systems.

Psychological Review, 2007

A detailed description of the simultaneous type, serial token (ST 2 ) model is presented. ST 2 is... more A detailed description of the simultaneous type, serial token (ST 2 ) model is presented. ST 2 is a model of temporal attention and working memory that encapsulates 5 principles: (a) M. M. Chun and M. C. Potter's (1995) 2-stage model, (b) a Stage 1 salience filter, (c) N. G. types-tokens distinction, (d) a transient attentional enhancement, and (e) a mechanism for associating types with tokens called the binding pool. The authors instantiate this theoretical position in a connectionist implementation, called neural-ST 2 , which they illustrate by modeling temporal attention results focused on the attentional blink (AB). They demonstrate that the ST 2 model explains a spectrum of AB findings. Furthermore, they highlight a number of new temporal attention predictions arising from the ST 2 theory, which are tested in a series of behavioral experiments. Finally, the authors review major AB models and theories and compare them with ST 2 . for discussions and input that have contributed to the development of the ST 2 model.

Journal of Vision, 2010

Abstract In a real-world context, brief glimpses of moving forms, especially people, are both pre... more Abstract In a real-world context, brief glimpses of moving forms, especially people, are both prevalent and salient. Yet in studies of search and selective attention, targets are typically static stimuli, such as characters, words, or pictures. In the present experiments, targets were briefly presented point-light walkers (PLWs), each consisting of a coherent set of moving dots that outline a person carrying out one of four actions (Serre & Giese 2007). The attentional blink (AB) is a deficit in reporting the second of two targets with an SOA of ...

Journal of Vision, 2010

A wealth of neurophysiological data has demonstrated that visual attention can selectively enhanc... more A wealth of neurophysiological data has demonstrated that visual attention can selectively enhance target representations early in the visual processing pathway. In addition, behavioural evidence tells us that the extent to which irrelevant items interfere with target processing depends on their featural similarity to the target. In this context, how does target discriminability influence temporal selection? We present results from an electrophysiology study that addresses this question by investigating the time course of the neural processes involved in target selection as target distinctiveness is varied. The results suggest that, in line with previous findings, making discrimination harder reduces the accuracy of target identification. We find that there are significant differences in the perceptual processing of the target in the two conditions, as indexed by early visual ERPs and the P3 ERP. We ground this and previous empirical evidence within a theoretical framework for understanding the mechanism of attentional selection represented in the ST 2 model, a neural network model of temporal attention and working memory. By simulating both experimental conditions, we show that the model provides a convincing explanation of the pattern of experimental results, in addition to informing questions about the nature and time course of attentional selection.

Journal of Vision, 2010

... Brad Wyble bw5{at}kent ... Abstract. It has recently been disputed whether working memory has... more ... Brad Wyble bw5{at}kent ... Abstract. It has recently been disputed whether working memory has a fixed capacity of 4 objects. Alvarez & Cavanagh (2004), for example, demonstrate that complex items appear to consume more resources than simple ones, reducing storage capacity. ...

This paper explores the feasibility of using EEG in the context of Stimulus Rich Reactive Interfa... more This paper explores the feasibility of using EEG in the context of Stimulus Rich Reactive Interfaces (SRRI's), as a source of feedback on the cognitive state of the user. We have run experiments to evaluate the utility of two potential EEG measures of whether a stimulus has been perceived: 1) reduced EEG power in the alpha band at posterior brain areas and 2) a P3-like positive deflection over parietal areas. Such measures would enable re-presentation of a critical stimulus that has been missed.