Automatic guidance of visual attention from verbal working memory.

Previous studies have shown that visual attention can be captured by stimuli matching the contents of working memory (WM). Here, the authors assessed the nature of the representation that mediates the guidance of visual attention from WM. Observers were presented with either verbal or visual primes (to hold in memory, Experiment 1; to verbalize, Experiment 2; or merely to attend, Experiment 3) and subsequently were required to search for a target among different distractors, each embedded within a colored shape. In half of the trials, an object in the search array matched the prime, but this object never contained the target. Despite this, search was impaired relative to a neutral baseline in which the prime and search displays did not match. An interesting finding is that verbal primes were effective in generating the effects, and verbalization of visual primes elicited similar effects to those elicited when primes were held in WM. However, the effects were absent when primes were only attended. The data suggest that there is automatic encoding into WM when items are verbalized and that verbal as well as visual WM can guide visual attention. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Serial deployment of attention during visual search.

This study examined whether objects are attended in serial or in parallel during a demanding visual search task. A component of the event-related potential waveform, the N2pc wave, was used as a continuous measure of the allocation of attention to possible targets in the search arrays. Experiment 1 demonstrated that the relative allocation of attention shifts rapidly, favoring one item and then another. In Experiment 2, a paradigm was used that made it possible to track the absolute allocation of attention to individual items. This experiment showed that attention was allocated to one object for 100-150 ms before attention began to be allocated to the next object. These findings support models of attention that posit serial processing in demanding visual search tasks. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Do the contents of working memory capture attention? Yes, but cognitive control matters.

There has been a controversy on whether working memory can guide attentional selection. Some researchers have reported that the contents of working memory guide attention automatically in visual search (D. Soto, D. Heinke, G. W. Humphreys, & M. J. Blanco, 2005). On the other hand, G.F. Woodman and S. J. Luck (2007) reported that they could not find any evidence of attentional capture by working memory. In the present study, we tried to find an integrative explanation for the different sets of results. We report evidence for attentional capture by working memory, but this effect was eliminated when search was perceptually demanding or the onset of the search was delayed long enough for cognitive control of search to be implemented under particular conditions. We suggest that perceptual difficulty and the time course of cognitive control as important factors that determine when information in working memory influences attention. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Measuring and modeling the trajectory of visual spatial attention.

In a novel choice attention-gating paradigm, observers monitor a stream of 3x3 letter arrays until a tonal cue directs them to report 1 row. Analyses of the particular arrays from which reported letters are chosen and of the joint probabilities of reporting pairs of letters are used to derive a theory of attention dynamics. An attention window opens 0.15 s following a cue to attend to a location, remains open (minimally) 0.2 s, and admits information simultaneously from all the newly attended locations. The window dynamics are independent of the distance moved. The theory accounts for about 90% of the variance from the over 400 data points obtained from each of the observers in the 3 experiments reported here. With minor elaborations, it applies to all the principal paradigms used to study the dynamics of visual spatial attention. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Infant visual recognition memory: Independent contributions of speed and attention.

Relations between infant visual recognition memory and later cognition have fueled interest in identifying the underlying cognitive components of this important infant ability. The present large-scale study examined three promising factors in this regard--processing speed, short-term memory capacity, and attention. Two of these factors, attention and processing speed (but, surprisingly, not short-term memory capacity), were related to visual recognition memory: Infants who showed better attention (shorter looks and more shifts) and faster processing had better recognition memory. The contributions of attention and processing speed were independent of one another and were similar at all ages studied--5, 7, and 12 months. Taken together, attention and speed accounted for 6%-9% of the variance in visual recognition memory, leaving a considerable, but not unexpected, portion of the variance unexplained. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Infant attention and visual preferences: Converging evidence from behavior, event-related potentials, and cortical source localization.

In this study, we had 3 major goals. The 1st goal was to establish a link between behavioral and event-related potential (ERP) measures of infant attention and recognition memory. To assess the distribution of infant visual preferences throughout ERP testing, we designed a new experimental procedure that embeds a behavioral measure (paired comparison trials) in the modified-oddball ERP procedure. The 2nd goal was to measure infant ERPs during the paired comparison trials. Independent component analysis (ICA) was used to identify and to remove eye-movement components from the electroencephalographic data, thus allowing for the analysis of ERP components during paired comparison trials. The 3rd goal was to localize the cortical sources of infant visual preferences. Equivalent current dipole analysis was performed on the ICA components related to experimental events. Infants who demonstrated novelty preferences in paired comparison trials demonstrated greater amplitude Negative central ERP components across tasks than infants who did not demonstrate novelty preferences. Visual preference also interacted with attention and stimulus type. The cortical sources of infant visual preferences were localized to inferior and superior prefrontal cortex and to the anterior cingulate cortex. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effect of items in working memory on the deployment of attention and the eyes during visual search.

Paying attention to an object facilitates its storage in working memory. The authors investigate whether the opposite is also true: whether items in working memory influence the deployment of attention. Participants performed a search for a prespecified target while they held another item in working memory. In some trials this memory item was present in the search display as a distractor. Such a distractor has no effect on search time if the search target is in the display. In that case, the item in working memory is unlikely to be selected as a target for an eye movement, and if the eyes do land on it, fixation duration is short. In the absence of the target, however, there is a small but significant effect of the memory item on search time. The authors conclude that the target for visual search has a special status in working memory that allows it to guide attention. Guidance of attention by other items in working memory is much weaker and can be observed only if the search target is not present in the display. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual word recognition without central attention: Evidence for greater automaticity with advancing age.

The present experiments examined the automaticity of word recognition. The authors examined whether people can recognize words while central attention is devoted to another task and how this ability changes across the life span. In Experiment 1, a lexical decision Task 2 was combined with either an auditory or a visual Task 1. Regardless of the Task 1 modality, Task 2 word recognition proceeded in parallel with Task 1 central operations for older adults but not for younger adults. This is a rare example of improved cognitive processing with advancing age. When Task 2 was nonlexical (Experiment 2), however, there was no evidence for greater parallel processing for older adults. Thus, the processing advantage appears to be restricted to lexical processes. The authors conclude that greater cumulative experience with lexical processing leads to greater automaticity, allowing older adults to more efficiently perform this stage in parallel with another task. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Characteristics of covert and overt visual orienting: Evidence from attentional and oculomotor capture.

Five visual search experiments found oculomotor and attentional capture consistent with predictions of contingent orienting, contrary to claims that oculomotor capture is purely stimulus driven. Separate saccade and attend-only conditions contained a color target appearing either singly, with an onset or color distractor, or both. In singleton mode, onsets produced oculomotor and attentional capture. In feature mode, capture was absent or greatly reduced, providing evidence for top-down modulation of both types of capture. Although attentional capture by color abstractors was present throughout, oculomotor capture by color occurred only when accompanied by transient change, providing evidence for a dissociation between oculomotor and attentional capture. Oculomotor and attentional capture appear to be mediated by top-down attentional control settings, but transient change may be necessary for oculomotor capture. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Serial and parallel attentive visual searches: Evidence from cumulative distribution functions of response times.

Participants searched a visual display for a target among distractors. Each of 3 experiments tested a condition proposed to require attention and for which certain models propose a serial search. Serial versus parallel processing was tested by examining effects on response time means and cumulative distribution functions. In 2 conditions, the results suggested parallel rather than serial processing, even though the tasks produced significant set-size effects. Serial processing was produced only in a condition with a difficult discrimination and a very large set-size effect. The results support C. Bundesen's (1990) claim that an extreme set-size effect leads to serial processing. Implications for parallel models of visual selection are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reactivity to visual signals and the cerebellar vermis: Evidence from a rare case with rhombencephalosynapsis.

The modulatory role of the cerebellum was investigated in a case with rhombencephalosynapsis (RS), a rare dysplasia characterized by the absence of the cerebellar vermis. The visual psychophysical task involved localizing a target and ignoring a distractor appearing either before, at the same time as, or after the target. It allowed us to assess reactivity to warning signals, distraction, and reactivity to signals appearing during attentive processing. Compared with a control sample, the patient exhibited greater reactivity to warning signals and difficulties interrupting attentive processing, whereas distraction was not increased. Complementary analyses showed that these deficits did not reflect just delayed development of attentional processes. These results suggest that the cerebellum modulates responsiveness and commands attentional/exploratory flexibility in response to sensory signals. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attention, spatial representation, and visual neglect: Simulating emergent attention and spatial memory in the selective attention for identification model (SAIM).

The selective attention for identification model (SAIM) is presented. This uses a spatial window to select visual information for recognition, binding parts to objects and generating translation-invariant recognition. The model provides a qualitative account of both normal and disordered attention. Simulations of normal attention demonstrate 2-object costs and effects of object familiarity on selection, global precedence, spatial cueing, and inhibition of return. When lesioned, SAIM demonstrated either view- or object-centered neglect or spatial extinction, depending on the type and extent of lesion. The model provides a framework to unify (a) object- and space-based theories of normal selection, (b) dissociations within the syndrome of unilateral neglect, and (c) attentional and representational accounts of neglect. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Disentangling the adult attention-deficit hyperactivity disorder endophenotype: Parametric measurement of attention.

Attention deficit hyperactivity disorder (ADHD) persists frequently into adulthood. The decomposition of endophenotypes by means of experimental neuro-cognitive assessment has the potential to improve diagnostic assessment, evaluation of treatment response, and disentanglement of genetic and environmental influences. We assessed four parameters of attentional capacity and selectivity derived from simple psychophysical tasks (verbal report of briefly presented letter displays) and based on a “theory of visual attention.” These parameters are mathematically independent, quantitative measures, and previous studies have shown that they are highly sensitive for subtle attention deficits. Potential reductions of attentional capacity, that is, of perceptual processing speed and working memory storage capacity, were assessed with a whole report paradigm. Furthermore, possible pathologies of attentional selectivity, that is, selection of task-relevant information and bias in the spatial distribution of attention, were measured with a partial report paradigm. A group of 30 unmedicated adult ADHD patients and a group of 30 demographically matched healthy controls were tested. ADHD patients showed significant reductions of working memory storage capacity of a moderate to large effect size. Perceptual processing speed, task-based, and spatial selection were unaffected. The results imply a working memory deficit as an important source of behavioral impairments. The theory of visual attention parameter working memory storage capacity might constitute a quantifiable and testable endophenotype of ADHD. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Anger management: Age differences in emotional modulation of visual processing.

Although positive and negative images enhance the visual processing of young adults, recent work suggests that a life-span shift in emotion processing goals may lead older adults to avoid negative images. To examine this tendency for older adults to regulate their intake of negative emotional information, the current study investigated age-related differences in the perceptual boost received by probes appearing over facial expressions of emotion. Visually-evoked event-related potentials were recorded from the scalp over cortical regions associated with visual processing as a probe appeared over facial expressions depicting anger, sadness, happiness, or no emotion. The activity of the visual system in response to each probe was operationalized in terms of the P1 component of the event-related potentials evoked by the probe. For young adults, the visual system was more active (i.e., greater P1 amplitude) when the probes appeared over any of the emotional facial expressions. However, for older adults, the visual system displayed reduced activity when the probe appeared over angry facial expressions. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Using the attention cascade model to probe cognitive aging.

Young and older adults searched for 2 digit targets among black letter distractors in rapid serial visual presentation. Unsurprisingly, relative to the young, the older adults performed worse on both targets and exhibited greater and longer attentional blink. The data of each group were computationally accounted for by the attention cascade model (Shih, 2008) with 7 parameters; the optimum values and 95% confidence intervals of the parameters were based on 10,000 bootstrap samples. There was no age effect on the width of the attention window or on the capacity of the consolidation processor. However, relative to the young, the older adults suffered more masking effects of the salient (and brighter) stimulus, required longer consolidation duration, and had greater and more widespread decision noise. The processing rate prior to working memory was numerically slower in older adults. Both age groups adopted inefficient strategy during the task—engaging the consolidation processor for an unnecessarily long period. Further simulations suggest that varying the duration can emulate strong or weak blinkers or nonblinkers. The attention cascade model appears a useful tool for the investigation of cognitive aging and other comparative studies. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Generalized signaling for control: Evidence from postconflict and posterror performance adjustments.

Goal-directed behavior requires cognitive control to effect online adjustments in response to ongoing processing demands. How signaling for these adjustments occurs has been a question of much interest. A basic question regarding the architecture of the cognitive control system is whether such signaling for control is specific to task context or generalizes across contexts. In this study, the authors explored this issue using a stimulus–response compatibility paradigm. They examined trial-to-trial adjustments, specifically, the findings that incompatible trials elicit improved performance on subsequent incompatible trials and that responses are slower after errors. The critical question was, Do such control effects—typically observed within a single task context—occur across task contexts? The paradigm involved 2 orthogonal, stimulus–response sets: Stimuli in the horizontal direction mapped only to responses in the horizontal direction, and likewise for the vertical direction. Cues indicated that either compatible (same direction as stimulus) or incompatible (opposite to stimulus) responses were required. The results showed that trial-to-trial adjustments exist for both direction-repeat and direction-switch trials, demonstrating that signaling for control adjustments can extend beyond the task context within which they arise. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On the nonautomaticity of visual word processing: Electrophysiological evidence that word processing requires central attention.

The present study used event-related potentials (ERPs) to determine the degree to which people can process words while devoting central attention to another task. Experiments 1-4 measured the N400 effect, which is sensitive to the degree of mismatch between a word and the current semantic context. Experiment 5 measured the P3 difference between low- and high-frequency words. Because these effects can occur only if a word has been identified, both ERP components index word processing. The authors found that the N400 effect (Experiments 1, 3, and 4) and the P3 difference (Experiment 5) were strongly attenuated for Task 2 words presented nearly simultaneously with Task 1. No such attenuation was found when the Task 1 stimulus was presented but required no response (Experiment 2). Strong attenuation was also evident when the Task 2 word was presented before the Task 1 stimulus (Experiment 4), suggesting that central resources are not allocated to stimuli first-come, first-served but rather are strategically locked to Task 1. The authors conclude that visual word processing is not fully automatic but rather requires access to limited central attentional resources. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Emotional expressions and visual search efficiency: Specificity and effects of anxiety symptoms.

Although facial expressions are thought to vary in their functional impact on perceivers, experimental demonstration of the differential effects of facial expressions on behavior are lacking. In the present study, we examined the effects of exposure to facial expressions on visual search efficiency. Participants (n = 31) searched for a target in a 12 location circle array after exposure to an angry, disgusted, fearful, happy, or neutral facial expression for 100 ms or 500 ms. Consistent with predictions, exposure to a fearful expression prior to visual search resulted in faster target identification compared to exposure to other facial expressions. The effects of other facial expressions on visual search did not differ from each other. The fear facilitating effect on visual search efficiency was observed at 500-ms but not at 100-ms presentations, suggesting a specific temporal course of the facilitation. Subsequent analysis also revealed that individual differences in fear of negative evaluation, trait anxiety, and obsessive–compulsive symptoms possess a differential pattern of association with visual search efficiency. The experimental and clinical implications of these findings are discussed. (PsycINFO Database Record (c) 2011 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)     

Independent representation of parts and the relations between them: Evidence from integrative agnosia.

Whether objects are represented as a collection of parts whose relations are coded independently remains a topic of ongoing discussion among theorists in the domain of shape perception. S. M., an individual with integrative agnosia, and neurologically intact ("normal") individuals learned initially to identify 4 target objects constructed of 2 simple volumetric parts. At test, the targets were mixed with distractors, some of which could be discriminated from the targets on the basis of a mismatching part, whereas the rest could be discriminated only on the basis of the altered spatial arrangements of parts. S. M. learned to identify the target objects, although at a rate slower than that of the normal participants. At test, he correctly rejected distractors on the basis of mismatching parts but was profoundly impaired at rejecting distractors made of the same local components but with mismatching spatial arrangements. These results suggest that encoding the spatial arrangements of parts of an object requires a mechanism that is different from that required for encoding the shape of individual parts, with the former selectively compromised in integrative agnosia. (PsycINFO Database Record (c) 2010 APA, all rights reserved)