Episodic theory of the dynamics of spatial attention.

Previous measurements of visual attention in simple reaction time, choice reaction time and complex discrimination experiments in which attention was purported to move continuously across space are reanalyzed. These data and data from attention gating experiments are quantitatively predicted by an episodic (quantal) theory of spatial attention that proposes instead: (1) visual attention can be resolved into a sequence of discrete attentional acts (episodes), (2) each attentional episode i is defined by its spatial attention function fi(x,y), (3) the smooth transition at time t? between episodes is described by a temporal transition function G(t–t?), and (4) f and G are space-time separable. In new experiments, which use a concurrent motor reaction time task to control for nonattentional factors, the duration of an attention transition is shown to be independent of the distance traversed and of the presence of interposed visual obstacles. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Categorically defined targets trigger spatiotemporal visual attention.

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 (K. Nakayama & M. Mackeben, 1989). 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 1 target preceded a second target in the same location at a stimulus onset asynchrony 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 2 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. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The attentional blink provides episodic distinctiveness: Sparing at a cost.

The attentional blink (J. E. Raymond, K. L. Shapiro, & K. M. Arnell, 1992) refers to an apparent gap in perception observed when a second target follows a first within several hundred milliseconds. Theoretical and computational work have provided explanations for early sets of blink data, but more recent data have challenged these accounts by showing that the blink is attenuated when subjects encode strings of stimuli (J. Kawahara, T. Kumada, & V. Di Lollo, 2006; M. R. Nieuwenstein & M. C. Potter, 2006; C. N. Olivers, 2007) or are distracted (C. N. Olivers & S. Nieuwenhuis, 2005) while viewing the rapid serial visual presentation stream. The authors describe the episodic simultaneous type, serial token model, a computational account of encoding visual stimuli into working memory that suggests that the attentional blink is a cognitive strategy rather than a resource limitation. This model is composed of neurobiologically plausible elements and simulates the attentional blink with a competitive attentional mechanism that facilitates the formation of episodically distinct representations within working memory. In addition to addressing the blink, the model addresses the phenomena of repetition blindness and whole report superiority, producing predictions that are supported by experimental work. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The Role of the Locus Coeruleus in Mediating the Attentional Blink: A Neurocomputational Theory.

The attentional blink refers to the transient impairment in perceiving the 2nd of 2 targets presented in close temporal proximity. In this article, the authors propose a neurobiological mechanism for this effect. The authors extend a recently developed computational model of the potentiating influence of the locus coeruleus-norepinephrine system on information processing and hypothesize that a refractoriness in the function of this system may account for the attentional blink. The model accurately simulates the time course of the attentional blink, including Lag 1 sparing. The theory also offers an account of the close relationship of the attentional blink to the electrophysiological P3 component. The authors report results from two behavioral experiments that support a critical prediction of their theory regarding the time course of Lag 1 sparing. Finally, the relationship between the authors' neurocomputational theory and existing cognitive theories of the attentional blink is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The beneficial effects of additional task load, positive affect, and instruction on the attentional blink.

The attentional blink reflects the impaired ability to identify the 2nd of 2 targets presented in close succession--a phenomenon that is generally thought to reflect a fundamental cognitive limitation. However, the fundamental nature of this impairment has recently been called into question by the counterintuitive finding that task-irrelevant mental activity improves attentional blink performance (C. N. L. Olivers & S. Nieuwenhuis, 2005). The present study found a reduced attentional blink when participants concurrently performed an additional memory task, viewed pictures of positive affective content, or were instructed to focus less on the task. These findings support the hypothesis that the attentional blink is due to an overinvestment of attentional resources in stimulus processing, a suboptimal processing mode that can be counteracted by manipulations promoting divided attention. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Diazepam impairs temporal dynamics of visual attention.

The effect of benzodiazepines on attention has been the object of few investigations. Studies using the spatial cueing paradigm (Posner's paradigm) have reported inconsistent results, which are likely due to methodological and/or dose differences but suggest impaired disengagement of attention from the cue to the target. The authors investigated the effect of a benzodiazepine (diazepam) on attentional shifting in the temporal domain. The attentional blink effect refers to difficulties in detecting a target if it follows the identification of a previous target occurring within a temporal window of 200-400 ms. The authors assessed whether the duration of the attentional blink was affected by diazepam. Streams of 15 real-world scenes displaying a road were presented for 50 ms each. A city name (target) appeared at Serial Positions 2, 3, or 4 of each stream. A vehicle (probe) appeared at different intervals following the city name. In a dual-task condition, participants were asked to report the city name and whether a vehicle was present. In a control condition, participants had to report only the presence of a vehicle and ignore the city name. Thirty-six healthy volunteers were assigned to 3 groups (placebo, diazepam 0.1 mg/kg, or 0.3 mg/kg). Diazepam increased both the magnitude and duration of the attentional blink effect. Participants treated with a high dose of diazepam needed more than 600 ms to detect a vehicle following identification of the name. Results suggest that diazepam at a therapeutic dosage affects attentional shifting in the temporal domain and impairs dual-task performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attention to visual pattern information produces the attentional blink in rapid serial visual presentation.

To investigate the temporal allocation of attention, a series of 7 experiments using rapid serial visual presentation was designed to examine the relationship of the attentional demands of various target tasks to the production of the subsequent visual attentional deficit, or "attentional blink" (AB), recently reported by J. E. Raymond et al (see record 1992-41685-001). The principal finding is that AB occurs only when a target is an object and does not occur when the target is defined by a temporal interval. Target detection difficulty as estimated by d′ analysis reveals no relationship between the attentional demands of the target and the production of the AB. A late-selection account of this phenomenon is offered in place of the early-selection account advanced in the previous report of Raymond et al. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Delayed Attentional Engagement in the Attentional Blink.

Observers often miss the 2nd of 2 visual targets (first target [T1] and second target [T2]) when these targets are presented closely in time; the attentional blink (AB). The authors hypothesized that the AB occurs because the attentional response to T2 is delayed by T1 processing, causing T2 to lose a competition for attention to the item that follows it. The authors investigated this hypothesis by determining whether the AB is attenuated when T2 is precued. The results from 4 experiments showed that the duration and magnitude of the AB were substantially reduced when T2 was precued. The observed improvement in T2 report did not occur at the expense of T1 report, suggesting that processing of T1 was already completed or was at least protected when the cue was presented. The authors conclude that, during the AB, there is a delay between detection and the selection of target candidates for consolidation in short-term memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Top-down contingencies in peripheral cuing: The roles of color and location.

According to contingent-processing accounts, peripheral cuing effects are due to the cues' inadvertent selection for processing by control settings set up for targets (e.g., C. L. Folk, R. W. Remington, & J. C. Johnston, 1992). Consequently, cues similar to targets should have stronger effects than do dissimilar cues. In the current study, this prediction is confirmed for cue-target combinations similar or dissimilar in the static features of color (Experiments 1-3) and location (Experiment 4), even when both cues and targets share the dynamic feature of abrupt onset. Perceptual priming (Experiment 2) and reallocation of attention did not account for similar-dissimilar differences (Experiments 3 and 4). The results are best explained by top-down-contingent attentional effects of the similar cues. Implications for bottom-up accounts of peripheral cuing effects are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Picture detection in rapid serial visual presentation: Features or identity?

A pictured object can be readily detected in a rapid serial visual presentation 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 (Evans & Treisman, 2005), or is identification of the object the basis for detection? When 2 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 2 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 (Wyble, Bowman, & Potter, 2009). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Relations as rules: The role of attention in the Dimensional Change Card Sort task.

Preschoolers are typically unable to switch sorting rules during the Dimensional Change Card Sort task. One explanation for this phenomenon is attentional inflexibility (Kirkham, Cruess, & Diamond, 2003). In 4 experiments with 3- to 4-year-olds, we tested this hypothesis by examining the influence of dimensional salience on switching performance. Results from these experiments demonstrated that it was more difficult for children to redirect attention from attribute-based rule sets, such as color and shape, than from spatial relational rule sets. Overall, these findings point to a role for attention in performance on the Dimensional Change Card Sort task. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effects of attention on age-related relational memory deficits: Evidence from a novel attentional manipulation.

Healthy aging is often accompanied by episodic memory decline. Prior studies have consistently demonstrated that older adults show disproportionate deficits in relational memory (RM) relative to item memory (IM). Despite rich evidence of an age-related RM deficit, the source of this deficit remains unspecified. One of the most widely investigated factors of age-related RM impairment is a reduction in attentional resources. However, no prior studies have demonstrated that reduced attentional resources are the critical source of age-related RM deficits. Here, we used qualitatively different attention tasks and tested whether reduced attention for relational processing underlies the RM deficit observed in aging. In Experiment 1, we imposed either item-detection or relation-detection attention tasks on young adults during episodic memory encoding and found that only the concurrent attention task that involves relational processing disproportionately impaired RM performance in young adults. Moreover, by ruling out the possible confound of task difficulty on the disproportionate RM impairment, we further demonstrated that reduced relational attention is a key factor for the age-related RM deficit. In Experiment 2, we replicated the results from Experiment 1 by using different materials of stimuli and found that the effect of relational attention on RM is material general. The results of Experiment 2 also showed that reducing attentional resources for relational processing in young adults strikingly equated their RM performance to that of older adults. Thus, this study documents the first evidence that reduced attentional resources for relational processing are a critical factor for the relational memory impairment observed in aging. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Semantic priming in young and older adults: Evidence for age constancy in automatic and attentional processes.

Automatic and attentional components of semantic priming and the relation of each to episodic memory were evaluated in young and older adults. Category names served as prime words, and the relatedness of the prime to a subsequent lexical decision target was varied orthogonally with whether the target category was expected or unexpected. At a prime-target stimulus-onset asynchrony (SOA) of 410 ms, target words in the same category had faster lexical decision latencies than did different category targets. This effect was not significant at a 1,550-ms SOA and was attributed to automatic processes. Expected category targets had faster latencies than unexpected category targets at the 410-ms SOA, and the magnitude of the effect increased at the 1,550-ms SOA. This effect was attributed to attentional processes. These patterns of priming were obtained for both age groups, but in a surprise memory test older adults had poorer recall of primes and targets. We discuss the implications of these results for the hypothesis that older adults suffer deficits in selective attention and for the related hypothesis that attentional deficits impair semantic processing, which causes memory decrements in old age. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Indirect Learning of Event Sequences: The Effects of Divided Attention and Stimulus Continuity.

In a serial reaction time (SRT) task, the learning curve is steeper when the stimuli are presented in a repeating sequential manner rather than in random order (Nissen & Bullemer, 1987). This is true even when subjects report being unaware of the presence of the repeating sequence. The present study examines the nature of this learning under conditions designed to reduce attentional resources and to disrupt the continuity of stimuli. In the first three experiments, subjects were trained in the SRT task, with or without the addition of a secondary tone counting task, and with repeating or non-repeating sequences. The results suggest that some sequence learning occurred despite the presence of a secondary task. Experiment 4 examined the extent of sequence learning when the inter-stimulus interval was varied between trials. The overall results suggest that despite reduced attentional allocation and discontinuous stimulus presentation, some sequence learning occurs. This result supports other work suggesting a dissociation between learning when measured explicitly, and when assessed through performance indicators. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Unmasking the attentional blink.

When asked to identify 2 visual targets (T1 and T2 for the 1st and 2nd targets, respectively) embedded in a sequence of distractors, observers will often fail to identify T2 when it appears within 200-500 ms of T1--an effect called the attentional blink. Recent work shows that attention does not blink when the task is to encode a sequence of consecutive targets, suggesting that distractor interference plays a causal role in the attentional blink. Here, however, the authors show that an attentional blink occurs even in the absence of distractors, with 2 letter targets separated by a blank interval. In addition, the authors found that the impairment for identification of the 2nd of 2 targets separated by a blank interval is substantially attenuated either when the intertarget interval is filled with additional target items or when the 2nd target is precued by an additional target. These findings show that the root cause of the blink lies in the difficulty of engaging attention twice within a short period of time for 2 temporally discrete target events. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Factors contributing to attentional impairments after traumatic brain injury.

The aim of the present study was to investigate the contribution of impaired information processing speed and strategic control of attention to performance on attentional tasks after traumatic brain injury (TBI). Forty moderately to severely injured rehabilitation inpatients and 40 healthy controls completed a selection of attentional tasks. Slowed processing speed in the TBI group was identified on the Symbol Digit Modalities Test (SDMT), 2&7 Selective Attention Test (2&7), Selective Attention (SAT), and Four Choice Reaction Time (4CRT) tasks. Impaired working memory was evident on the Letter Number Sequencing (LNS) task. Structural equation modeling revealed that the group difference in RT on the complex SAT was accounted for by slowed speed of processing on the simple SAT, and not working memory. TBI participants made more errors and missed responses on the complex version of the SAT, suggesting impairment in some aspects of strategic control of attention, and appeared unable to benefit from the automatic condition of the 2&7 Test. There was little evidence of deficit on the Sustained Attention to Response Task (SART). The present study provides evidence for a significant contribution of slowed processing speed to impaired performance on attentional tasks after TBI. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Crossmodal links between vision and touch in covert endogenous spatial attention.

The authors report a series of 6 experiments investigating crossmodal links between vision and touch in covert endogenous spatial attention. When participants were informed that visual and tactile targets were more likely on one side than the other, speeded discrimination responses (continuous vs. pulsed, Experiments 1 and 2; or up vs. down, Experiment 3) for targets in both modalities were significantly faster on the expected side, even though target modality was entirely unpredictable. When participants expected a target on a particular side in just one modality, corresponding shifts of covert attention also took place in the other modality, as evidenced by faster elevation judgments on that side (Experiment 4). Larger attentional effects were found when directing visual and tactile attention to the same position rather than to different positions (Experiment 5). A final study with crossed hands revealed that these visuotactile links in spatial attention apply to common positions in external space. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perception of Objects in Natural Scenes: Is It Really Attention Free?

Studies have suggested attention-free semantic processing of natural scenes in which concurrent tasks leave category detection unimpaired (e.g., F. Li, R. VanRullen, C. Koch, & P. Perona, 2002). Could this ability reflect detection of disjunctive feature sets rather than high-level binding? Participants detected an animal target in a rapid serial visual presentation (RSVP) sequence and then reported its identity and location. They frequently failed to identify or to localize targets that they had correctly detected, suggesting that detection was based only on partial processing. Detection of targets was considerably worse in sequences that also contained humans, presumably because of shared features. When 2 targets were presented in RSVP, a prolonged attentional blink appeared that was almost eliminated when both targets were detected without being identified. The results suggest rapid feature analysis mediating detection, followed by attention-demanding binding for identification and localization. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

To look or not to look: An eye movement study of hypervigilance during change detection in high and low spider fearful students.

Previous eye movement studies of attentional bias in spider fear reported inconsistent results with respect to early attentional capture, suggesting that overt attentional capture only reliably occurs under specific circumstances. In addition, none of these studies explored covert attention. The present study examined attentional bias in spider phobia using a change detection paradigm that was expected to provide good conditions for documenting attentional capture. In contrast to our expectations, eye movement data showed that all participants' first fixations were fastest on general negative targets, whereas participants' first fixations on spider targets were slower in the spider fearful than in the nonfearful group. In addition, spider fearful participants made more nontarget fixations before fixating on a spider target than did nonfearful participants. Thus, we found that participants' overt attention was more quickly focused on general negative targets, whereas covert attentional processes enabled initial avoidance of fear-relevant (i.e. spider) stimuli. The present findings have important implications for research on attention and fear as they indicate that fearful individuals are not characterized by static attentional orienting toward threat but, under certain conditions, may avert attention from threat automatically. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

A Psychophysical Measure of Attention Deficit in Children With Attention-Deficit/Hyperactivity Disorder.

The authors explored the temporal mechanism of attention deficit in children with attention-deficit/hyperactivity disorder (ADHD). In rapid serial visual presentation tasks in which two targets (T? and T?) were presented in close temporal proximity among distractors, participants tried to identify T? and detect T? in one (dual-task) experiment and only to detect T? in a second control (single-task) experiment. The sensitivity of T? detection was analyzed using signal detection theory. The attentional blink--the impairment in T? detection following the identification of T?--was increased in magnitude and protracted in the patients. Moreover, some ADHD children appeared to have a blink largely normal in magnitude but temporally displaced toward a later time. The authors hypothesize that a slower closing of the attention gate may mediate this specific attention impairment in ADHD children. (PsycINFO Database Record (c) 2010 APA, all rights reserved)