Binding objects to locations: The relationship between object files and visual working memory.

The relationship between object files and visual working memory (VWM) was investigated in a new paradigm combining features of traditional VWM experiments (color change detection) and object-file experiments (memory for the properties of moving objects). Object-file theory was found to account for a key component of object-position binding in VWM: With motion, color memory came to be associated with the new locations of objects. However, robust binding to the original locations was found despite clear evidence that the objects had moved. This latter binding appears to constitute a scene-based component in VWM, which codes object location relative to the abstract spatial configuration of the display and is largely insensitive to the dynamic properties of objects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Associative Learning Improves Visual Working Memory Performance.

The ability to remember visual stimuli over a short delay period is limited by the small capacity of visual working memory (VWM). Here the authors investigate the role of learning in enhancing VWM. Participants saw 2 spatial arrays separated by a 1-s interval. The 2 arrays were identical except for 1 location. Participants had to detect the difference. Unknown to the participants, some spatial arrays would repeat once every dozen trials or so for up to 32 repetitions. Spatial VWM performance increased significantly when the same location changed across display repetitions, but not at all when different locations changed from one display repetition to another. The authors suggest that a major role of learning in VWM is to mediate which information gets retained, rather than to directly increase VWM capacity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Method matters: Systematic effects of testing procedure on visual working memory sensitivity.

Visual working memory (WM) is traditionally considered a robust form of visual representation that survives changes in object motion, observer's position, and other visual transients. This article presents data that are inconsistent with the traditional view. We show that memory sensitivity is dramatically influenced by small variations in the testing procedure, supporting the idea that representations in visual WM are susceptible to interference from testing. In the study, participants were shown an array of colors to remember. After a short retention interval, memory for one of the items was tested with either a same–different task or a 2-alternative-forced-choice (2AFC) task. Memory sensitivity was much lower in the 2AFC task than in the same–different task. This difference was found regardless of encoding similarity or of whether visual WM required a fine or coarse memory resolution. The 2AFC disadvantage was reduced when participants were informed shortly before testing which item would be probed. The 2AFC disadvantage diminished in perceptual tasks and was not found in tasks probing visual long-term memory. These results support memory models that acknowledge the labile nature of visual WM and have implications for the format of visual WM and its assessment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Binding in short-term visual memory.

The integration of complex information in working memory, and its effect on capacity, shape the limits of conscious cognition. The literature conflicts on whether short-term visual memory represents information as integrated objects. A change-detection paradigm using objects defined by color with location or shape was used to investigate binding in short-term visual memory. Results showed that features from the same dimension compete for capacity, whereas features from different dimensions can be stored in parallel. Binding between these features can occur, but focused attention is required to create and maintain the binding over time, and this integrated format is vulnerable to interference. In the proposed model, working memory capacity is limited both by the independent capacity of simple feature stores and by demands on attention networks that integrate this distributed information into complex but unified thought objects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The comparison of visual working memory representations with perceptual inputs.

The human visual system can notice differences between memories of previous visual inputs and perceptions of new visual inputs, but the comparison process that detects these differences has not been well characterized. In this study, the authors tested the hypothesis that differences between the memory of a stimulus array and the perception of a new array are detected in a manner that is analogous to the detection of simple features in visual search tasks. That is, just as the presence of a task-relevant feature in visual search can be detected in parallel, triggering a rapid shift of attention to the object containing the feature, the presence of a memory–percept difference along a task-relevant dimension can be detected in parallel, triggering a rapid shift of attention to the changed object. Supporting evidence was obtained in a series of experiments in which manual reaction times, saccadic reaction times, and event-related potential latencies were examined. However, these experiments also showed that a slow, limited-capacity process must occur before the observer can make a manual change detection response. (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)     

A central capacity limit to the simultaneous storage of visual and auditory arrays in working memory.

If working memory is limited by central capacity (e.g., the focus of attention; N. Cowan, 2001), then storage limits for information in a single modality should apply also to the simultaneous storage of information from different modalities. The authors investigated this by combining a visual-array comparison task with a novel auditory-array comparison task in 5 experiments. Participants were to remember only the visual, only the auditory (unimodal memory conditions), or both arrays (bimodal memory conditions). Experiments 1 and 2 showed significant dual-task tradeoffs for visual but not for auditory capacity. In Experiments 3-5, the authors eliminated modality-specific memory by using postperceptual masks. Dual-task costs occurred for both modalities, and the number of auditory and visual items remembered together was no more than the higher of the unimodal capacities (visual: 3-4 items). The findings suggest a central capacity supplemented by modality- or code-specific storage and point to avenues for further research on the role of processing in central storage. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Interrupted visual searches reveal volatile search memory.

This study investigated memory from interrupted visual searches. Participants conducted a change detection search task on polygons overlaid on scenes. Search was interrupted by various disruptions, including unfilled delay, passive viewing of other scenes, and additional search on new displays. Results showed that performance was unaffected by short intervals of unfilled delay or passive viewing, but it was impaired by additional search tasks. Across delays, memory for the spatial layout of the polygons was retained for future use, but memory for polygon shapes, background scene, and absolute polygon locations was not. The authors suggest that spatial memory aids interrupted visual searches, but the use of this memory is easily disrupted by additional searches. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A core knowledge architecture of visual working memory.

[Correction Notice: An erratum for this article was reported in Vol 37(3) of Journal of Experimental Psychology: Human Perception and Performance (see record 2011-10888-001). The supplemental materials DOI is incorrect. The correct DOI for the supplemental materials is provided in the erratum.] Visual working memory (VWM) is widely thought to contain specialized buffers for retaining spatial and object information: a 'spatial-object architecture.' However, studies of adults, infants, and nonhuman animals show that visual cognition builds on core knowledge systems that retain more specialized representations: (1) spatiotemporal representations for object tracking, (2) object identity representations for object recognition, and (3) view-dependent snapshots for place recognition. In principle, these core knowledge systems may retain information separately from one another. Consistent with this hypothesis, this study provides evidence that these three types of information are subject to independent working memory storage limits. These results, combined with those from previous studies, indicate that VWM contains three specialized buffers for retaining spatiotemporal information, object identity information, and snapshot information. Thus, VWM buffers parallel core knowledge systems. This 'core knowledge architecture' links the study of visual working memory to the study of the biological foundations of visual cognition. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Feature-based memory-driven attentional capture: Visual working memory content affects visual attention.

In 7 experiments, the authors explored whether visual attention (the ability to select relevant visual information) and visual working memory (the ability to retain relevant visual information) share the same content representations. The presence of singleton distractors interfered more strongly with a visual search task when it was accompanied by an additional memory task. Singleton distractors interfered even more when they were identical or related to the object held in memory, but only when it was difficult to verbalize the memory content. Furthermore, this content-specific interaction occurred for features that were relevant to the memory task but not for irrelevant features of the same object or for once-remembered objects that could be forgotten. Finally, memory-related distractors attracted more eye movements but did not result in longer fixations. The results demonstrate memory-driven attentional capture on the basis of content-specific representations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spatial context learning survives interference from working memory load.

The human visual system is constantly confronted with an overwhelming amount of information, only a subset of which can be processed in complete detail. Attention and implicit learning are two important mechanisms that optimize vision. This study addressed the relationship between these two mechanisms. Specifically we asked, Is implicit learning of spatial context affected by the amount of working memory load devoted to an irrelevant task? We tested observers in visual search tasks where search displays occasionally repeated. Observers became faster when searching repeated displays than unrepeated ones, showing contextual cuing. We found that the size of contextual cuing was unaffected by whether observers learned repeated displays under unitary attention or when their attention was divided using working memory manipulations. These results held when working memory was loaded by colors, dot patterns, individual dot locations, or multiple potential targets. We conclude that spatial context learning is robust to interference from manipulations that limit the availability of attention and working memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

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)     

Do the contents of visual working memory automatically influence attentional selection during visual search?

In many theories of cognition, researchers propose that working memory and perception operate interactively. For example, in previous studies researchers have suggested that sensory inputs matching the contents of working memory will have an automatic advantage in the competition for processing resources. The authors tested this hypothesis by requiring observers to perform a visual search task while concurrently maintaining object representations in visual working memory. The hypothesis that working memory activation produces a simple but uncontrollable bias signal leads to the prediction that items matching the contents of working memory will automatically capture attention. However, no evidence for automatic attentional capture was obtained; instead, the participants avoided attending to these items. Thus, the contents of working memory can be used in a flexible manner for facilitation or inhibition of processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

What Kind of Memory Supports Visual Marking?

In visual search tasks, if a set of items is presented for 1 s before another set of new items (containing the target) is added, search can be restricted to the new set. The process that eliminates old items from search is visual marking. This study investigates the kind of memory that distinguishes the old items from the new items during search. Using an accuracy paradigm in which perfect marking results in 100% accuracy and lack of marking results in near chance performance, the authors show that search can be restricted to new items not by visual short-term memory (VSTM) of old locations but by a limited capacity and slow-decaying VSTM of new locations and a high capacity and fast-decaying memory for asynchrony. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Understanding the function of visual short-term memory: Transsaccadic memory, object correspondence, and gaze correction.

Visual short-term memory (VSTM) has received intensive study over the past decade, with research focused on VSTM capacity and representational format. Yet, the function of VSTM in human cognition is not well understood. Here, the authors demonstrate that VSTM plays an important role in the control of saccadic eye movements. Intelligent human behavior depends on directing the eyes to goal-relevant objects in the world, yet saccades are very often inaccurate and require correction. The authors hypothesized that VSTM is used to remember the features of the current saccade target so that it can be rapidly reacquired after an errant saccade, a task faced by the visual system thousands of times each day. In 4 experiments, memory-based gaze correction was accurate, fast, automatic, and largely unconscious. In addition, a concurrent VSTM load interfered with memory-based gaze correction, but a verbal short-term memory load did not. These findings demonstrate that VSTM plays a direct role in a fundamentally important aspect of visually guided behavior, and they suggest the existence of previously unknown links between VSTM representations and the occulomotor system. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of attention in the maintenance of feature bindings in visual short-term memory.

This study examined the role of attention in maintaining feature bindings in visual short-term memory. In a change-detection paradigm, participants attempted to detect changes in the colors and orientations of multiple objects; the changes consisted of new feature values in a feature-memory condition and changes in how existing feature values were combined in a binding-memory condition. In the critical experiment, a demanding visual search task requiring sequential shifts of spatial attention was interposed during the delay interval of the change-detection task. If attention is more important for the maintenance of feature bindings than for the maintenance of unbound feature values, the attention-requiring search task should specifically disrupt performance in the binding-memory task. Contrary to this proposal, it was found that memory for bindings and memory for features were equally impaired by the search task. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Evidence for proactive interference in the focus of attention of working memory.

Proactive interference (PI) occurs when an earlier item interferes with memory for a newer item. Whereas some researchers (e.g., Surprenant & Neath, 2009a) argue that PI can be observed in all memory systems, some multiple systems theorists (e.g., Cowan, 1999) propose that items in the focus of attention of working memory are immune to PI. Two experiments tested whether PI occurs when the to-be-remembered items are assumed, by multiple-systems theorists, to be held in the focus of attention. In each experiment, subjects saw four trials in a row with the same type of to-be-remembered items, followed by four trials in a row with a different type of material. On each trial, only 3 stimuli were shown, which is below the capacity limit of the focus of attention, and subjects were asked if a probe item was one of those 3 items seen. In both experiments, response time increased from Trial 1 to Trial 4, suggesting that items from the earlier trials interfered with memory on the later trials. In addition, release from PI was shown in that response times decreased with a change of materials. The results replicate those first reported by Hanley and Scheirer (1975), and pose a problem for theorists who argue that parts of short-term memory are immune to PI. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spiders crawl easily through the bottleneck: Visual working memory for negative stimuli.

The special status of spiders in the attentional bottleneck and visual working memory (VWM) was studied. 23 spider-fearfuls (SF) and 23 non-anxious controls (NACs) participated in a serial VWM-task. Each trial showed a 4 × 4 matrix of images and 5 of these were subsequently cued for 150 ms each. Afterwards, one of the 16 displayed images was hidden and probed. The spider image was included in the string of 5 cued images, among the 11 uncued items, or not at all. For both groups, memory was better for cued spiders than for other cued items. SFs also showed improved memory for uncued spiders. The relevance of the results for theories of attention and cognitive models of phobias are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Implicit change identification: A replication of Fernandez-Duque and Thornton (2003).

Using a simple change detection task involving vertical and horizontal stimuli, I. M. Thornton and D. Fernandez-Duque (2000) showed that the implicit detection of a change in the orientation of an item influences performance in a subsequent orientation judgment task. However, S. R. Mitroff, D. J. Simons, and S. L. Franconeri (2002) were not able to replicate this finding after correcting for confounds and thus attributed Thornton and Fernandez-Duque's results to methodological artifacts. Because Mitroff et al.'s failure to replicate might in turn have stemmed from several methodological differences between their study and those of Thornton and Fernandez-Duque (2000) and Fernandez-Duque and Thornton (see record 2003-08747-002), the current authors set out to conduct a further replication in which they corrected all known methodological biases identified so far. The results suggest that implicit change detection indeed occurs: People's conscious decisions about the orientation of an item appear to be influenced by previous undetected changes in the orientation of other items in the display. Implications of this finding in light of current theories of visual awareness are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

"A core knowledge architecture of visual working memory": Correction to Wood (2011).

Reports an error in "A core knowledge architecture of visual working memory" by Justin N. Wood (Journal of Experimental Psychology: Human Perception and Performance, 2011[Apr], Vol 37[2], 357-381). The supplemental materials DOI is incorrect. The correct DOI for the supplemental materials is provided in the erratum. (The following abstract of the original article appeared in record 2011-06411-002.) Visual working memory (VWM) is widely thought to contain specialized buffers for retaining spatial and object information: a 'spatial-object architecture.' However, studies of adults, infants, and nonhuman animals show that visual cognition builds on core knowledge systems that retain more specialized representations: (1) spatiotemporal representations for object tracking, (2) object identity representations for object recognition, and (3) view-dependent snapshots for place recognition. In principle, these core knowledge systems may retain information separately from one another. Consistent with this hypothesis, this study provides evidence that these three types of information are subject to independent working memory storage limits. These results, combined with those from previous studies, indicate that VWM contains three specialized buffers for retaining spatiotemporal information, object identity information, and snapshot information. Thus, VWM buffers parallel core knowledge systems. This 'core knowledge architecture' links the study of visual working memory to the study of the biological foundations of visual cognition. (PsycINFO Database Record (c) 2011 APA, all rights reserved)