What drives memory-driven attentional capture? The effects of memory type, display type, and search type.

An important question is 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. Some past research has indicated that they do: Singleton distractors interfered more strongly with a visual search task when they were identical or related to the object held in memory. However, other research has failed to find such effects despite using very similar procedures. The present study, using the same combined working memory and attentional capture paradigm, demonstrates which factors do (varied mapping, low stimulus energy) and which factors do not (exact type of visual memory method used, difficult nature of search, heterogeneity of displays, and instruction) contribute to this discrepancy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Scene and position specificity in visual memory for objects.

This study investigated whether and how visual representations of individual objects are bound in memory to scene context. Participants viewed a series of naturalistic scenes, and memory for the visual form of a target object in each scene was examined in a 2-alternative forced-choice test, with the distractor object either a different object token or the target object rotated in depth. In Experiments 1 and 2, object memory performance was more accurate when the test object alternatives were displayed within the original scene than when they were displayed in isolation, demonstrating object-to-scene binding. Experiment 3 tested the hypothesis that episodic scene representations are formed through the binding of object representations to scene locations. Consistent with this hypothesis, memory performance was more accurate when the test alternatives were displayed within the scene at the same position originally occupied by the target than when they were displayed at a different position. (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)     

The role of visual working memory in attentive tracking of unique objects.

When tracking moving objects in space humans usually attend to the objects’ spatial locations and update this information over time. To what extent do surface features assist attentive tracking? In this study we asked participants to track identical or uniquely colored objects. Tracking was enhanced when objects were unique in color. The benefit was greater when the distance between distractors and targets was smaller, but was eliminated when the objects changed colors 1 to 4 times per second, even though at any instant they were always uniquely colored. In addition, tracking uniquely colored objects impaired a secondary color-memory task more than tracking identical objects, and holding several colors in working memory eliminated the advantage of tracking uniquely colored objects. Contrary to previous studies showing that feature information is poorly retained during tracking, these findings indicate that surface properties are stored in visual working memory to facilitate tracking performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual working memory for observed actions.

Human society depends on the ability to remember the actions of other individuals, which is information that must be stored in a temporary buffer to guide behavior after actions have been observed. To date, however, the storage capacity, contents, and architecture of working memory for observed actions are unknown. In this article, the author shows that it is possible to retain information about only 2-3 actions in visual working memory at once. However, it is also possible to retain 9 properties distributed across 3 actions almost as well as 3 properties distributed across 3 actions, showing that working memory stores integrated action representations rather than individual properties. Finally, the author shows that working memory for observed actions is independent from working memory for object and spatial information. These results provide evidence for a previously undocumented system in working memory for storing information about actions. Further, this system operates by the same storage principles as visual working memory for object information. Thus, working memory consists of a series of distinct yet computationally similar mechanisms for retaining different types of visual information. (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)     

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)     

Trade-offs between gaze and working memory use.

Eye movements during natural tasks suggest that observers do not use working memory to capacity but instead use eye movements to acquire relevant information immediately before needed. Results here however, show that this strategy is sensitive to memory load and to observers' expectations about what information will be relevant. Depending upon the predictability of what object features would be needed in a brick sorting task, subjects spontaneously modulated the order in which they sampled and stored visual information using working memory more when the task was predictable and reverting to a just-in-time strategy when the task was unpredictable and the memory load was higher. This self organization was evidenced by subjects' sequence of eye movements and also their sorting decisions following missed feature changes. These results reveal that attentional selection, fixations, and use of working memory reflect a dynamic optimization with respect to a set of constraints, such as task predictablity and memory load. They also reveal that change blindness depends critically on the local task context, by virtue of its influence on the information selected for storage in working memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

How task representations guide attention: Further evidence for the shielding function of task sets.

To pursue goal directed behavior, the cognitive system must be shielded against interference from irrelevant information. Aside from the online adjustment of cognitive control widely discussed in the literature, an additional mechanism of preventive goal shielding is suggested that circumvents irrelevant information from being processed in the first place. Participants had to react to 8 different words depicting clothing items that were presented in front of line drawings that could be either semantically related (clothes) or unrelated (animals with spatial orientation) to the target words. Participants either learned the stimulus–response (S–R) mappings by heart or used 1 task set (TS). In the S–R group, semantically related and unrelated distractors interfered with performance, whereas in the TS group, only semantically related distractors interfered, and unrelated distractors had no effect. It follows that task representations based on a general TS help to focus attention on relevant information, thereby preventing the processing of irrelevant information. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Symbolic control of visual attention: The role of working memory and attentional control settings.

This study examined how 1 symbol is selected to control the allocation of attention when several symbols appear in the visual field. In Experiments 1-3, the critical target feature was color, and it was found that uninformative central arrows that matched the color of the target were selected and produced unintentional shifts of attention (i.e., involuntary, initiated slowly, producing long-lasting facilitatory effects). Experiment 4 tested whether such selection is the result of an attentional filter or of a competition bias due to a match of incoming information against integrated object representations stored in working memory. Here, the critical feature was shape and color was irrelevant, but matching color arrows were still selected. Thus, features of objects in working memory will bias the selection of symbols in the visual field, and such selected symbols are capable of producing unintentional shifts of attention. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Object-position binding in visual memory for natural scenes and object arrays.

Nine experiments examined the means by which visual memory for individual objects is structured into a larger representation of a scene. Participants viewed images of natural scenes or object arrays in a change detection task requiring memory for the visual form of a single target object. In the test image, 2 properties of the stimulus were independently manipulated: the position of the target object and the spatial properties of the larger scene or array context. Memory performance was higher when the target object position remained the same from study to test. This same-position advantage was reduced or eliminated following contextual changes that disrupted the relative spatial relationships among contextual objects (context deletion, scrambling, and binding change) but was preserved following contextual change that did not disrupt relative spatial relationships (translation). Thus, episodic scene representations are formed through the binding of objects to scene locations, and object position is defined relative to a larger spatial representation coding the relative locations of contextual objects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Adult age differences in the use of distractor homogeneity during visual search.

Previous research has suggested that an age-related decline may exist in the ability to inhibit distracting information during visual search. The present experiments used a conjunction search task in which the within-item features of the target (an upright L) and the distractors (rotated Ls) were identical. In each of 2 experiments, both young and older adults searched the display significantly more rapidly when the distractors were all rotated in the same direction (homogeneous) than when the distractors were rotated in different directions (heterogeneous). The concept of a generalized, age-related slowing was able to account for many aspects of the data, although the degree of relative improvement associated with distractor homogeneity was greater for young adults than for older adults. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Central perceptual load does not reduce ipsilesional flanker interference in parietal extinction.

In healthy individuals, filtering of distractors improves when the perceptual difficulty, or load, of a central task increases. Following an earlier study by Lavie and Robertson (2001), this study examined whether increasing the perceptual load of a visual discrimination task attenuates the influence of ipsilesional and contralesional distractors in patients with spatial extinction. The authors used a flanker task in which participants identified a central target letter flanked by congruent, incongruent, or neutral distractors in the left and right hemifields. Perceptual load was manipulated by positioning the central target letter above or below a hash mark (#) in the low-load condition, or a letter ("R") in the high-load condition. Target identification was significantly more difficult under high load than low load. Despite this difference in task difficulty, the interference from incongruent flankers was equivalent across the two load conditions, for both contralesional and ipsilesional flankers. Our results suggest that perceptual load does not attenuate the distracting influence of ipsilesional stimuli. Rather, selectivity is strongly influenced by the strength of representations in brain areas that code salience across the visual field. (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)     

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)     

When visual marking meets the attentional blink: More evidence for top-down, limited-capacity inhibition.

An attentional blink (AB) paradigm was used to investigate the attentional resources necessary for visual marking. The results showed that distractors presented inside the AB cannot easily be ignored despite participants anticipating a future target display. This supports the hypothesis that attentional resources are required for visual marking. In addition, probe dots were better detected on blinked distractors than on successfully ignored distractors, but only when the task required new items to be prioritized. In a final experiment, a stronger negative carry-over effect on search occurred for targets identical to distractors presented outside rather than inside the AB. This suggests that at least part of the inhibitory processes involved in visual marking are nonspatial. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Interactions between search mechanisms in conjuction search.

We report the results of a technique designed to measure interactions between different visual search processes. We interrupted pop-out search before it produced a detection response, by adding extra distractors to the display so that a target initially defined by a single feature difference could then only be found on the basis of the conjunction of two features. This technique has been used to measure the duration of the perceptual components of pop-out search, independent of overall response time, for targets presented among different sets of distractors. In addition, when pop-out failed because it was interrupted, past work has shown that it nevertheless provided useful information to the processes responsible for difficult search. That is, partial pop-out assisted difficult search, when extra distractors made search difficult because the target was between the two types of distractors in the relevant feature space (E. Olds, W. Cowan, & P. Jolicoeur, 2000a,b,c). The present results demonstrate that partial pop-out also assists difficult search when difficult search is a conjunction search, and therefore these interactions may occur at a stage where information from different feature dimensions is combined. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Task Demands Control Acquisition and Storage of Visual Information.

Attention and working memory limitations set strict limits on visual representations, yet researchers have little appreciation of how these limits constrain the acquisition of information in ongoing visually guided behavior. Subjects performed a brick sorting task in a virtual environment. A change was made to 1 of the features of the brick being held on about 10% of trials. Rates of change detection for feature changes were generally low and depended on the pick-up and put-down relevance of the feature to the sorting task. Subjects' sorting decision suggests that changes may be missed because of a failure to update the changed feature. The authors also explore how hand and eye behavior are coordinated for strategic acquisition and storage of visual information throughout the task. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Orienting attention in visual working memory reduces interference from memory probes.

Given a changing visual environment, and the limited capacity of visual working memory (VWM), the contents of VWM must be in constant flux. Using a change detection task, the authors show that VWM is subject to obligatory updating in the face of new information. Change detection performance is enhanced when the item that may change is retrospectively cued 1 s after memory encoding and 0.5 s before testing. The retro-cue benefit cannot be explained by memory decay or by a reduction in interference from other items held in VWM. Rather, orienting attention to a single memory item makes VWM more resistant to interference from the test probe. The authors conclude that the content of VWM is volatile unless it receives focused attention, and that the standard change detection task underestimates VWM capacity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

When is search for a static target among dynamic distractors efficient?

Intuitively, dynamic visual stimuli, such as moving objects or flashing lights, attract attention. Visual search tasks have revealed that dynamic targets among static distractors can indeed efficiently guide attention. The present study shows that the reverse case, a static target among dynamic distractors, allows for relatively efficient selection in certain but not all cases. A static target was relatively efficiently found among distractors that featured apparent motion, corroborating earlier findings. The important new finding was that static targets were equally easily found among distractors that blinked on and off continuously, even when each individual item blinked at a random rate. However, search for a static target was less efficient when distractors abruptly varied in luminance but did not completely disappear. The authors suggest that the division into the parvocellular pathway dealing with static visual information, on the one hand, and the magnocellular pathway common to motion and new object onset detection, on the other hand, allows for efficient filtering of dynamic and static information. (PsycINFO Database Record (c) 2010 APA, all rights reserved)