A Computational Approach to Search in Visual Working Memory (original) (raw)

The Representation of Visual Working Memory

2016

Visual working memory (VWM) is a construct hypothesized to store a small amount of accurate perceptual information that can be brought to bear on a task. Much research concerns the construct’s capacity and the precision of the information stored. Two prominent theories of VWM representations have emerged: slot-based and continuous-resource mechanisms. Prior modeling work suggests that a continuous resource that varies over trials with variable capacity and a potential to make localization errors best accounts for the empirical data. Questions remain regarding the variability in VWM capacity and precision. Using a novel eye-tracking paradigm, we demonstrate that VWM facilitates search and exhibits effects of fixation frequency and recency, particularly for prior targets. Whereas slot-based memory models cannot account for the human data, a novel continuous-resource model provides a better fit and identifies the relevant resource as item activation.

The relationship between working memory and the dual-target cost in visual search guidance

Journal of Experimental Psychology: Human Perception and Performance

Searching for two targets produces a dual-target cost compared with single-target search, with reduced attentional guidance towards targets (Stroud, Menneer, Cave, & Donnelly, 2012). We explore the effect of holding a color in working memory (WM) on guidance in single-target search. In Experiments 1 and 2, participants searched for a T of a specific color while holding one of the following in WM: a color patch, a letter, a dot pattern, or an oriented bar. Only when holding a color in WM was guidance in single-target search affected as strongly as it is in dual-target search. In Experiment 3, the target changed color from trial to trial. A color in WM reduced guidance, but not to the extent of dual-target search. However, search and WM error rates were high, suggesting interference and incomplete engagement with the combined task. We conclude that the guidance cost in dualtarget search is not solely due to attentional capture by the WM-color, because the WM-color can be effectively separated from search color, with little confusion between the two. However, WM load does cause substantial interference in guidance when both tasks involve color. These results illustrate the complex interactions between working memory and attentional guidance.

The precision of visual working memory is set by allocation of a shared resource

Journal of Vision, 2009

The mechanisms underlying visual working memory have recently become controversial. One account proposes a small number of memory "slots," each capable of storing a single visual object with fixed precision. A contrary view holds that working memory is a shared resource, with no upper limit on the number of items stored; instead, the more items that are held in memory, the less precisely each can be recalled. Recent findings from a color report task have been taken as crucial new evidence in favor of the slot model. However, while this task has previously been thought of as a simple test of memory for color, here we show that performance also critically depends on memory for location. When errors in memory are considered for both color and location, performance on this task is in fact well explained by the resource model. These results demonstrate that visual working memory consists of a common resource distributed dynamically across the visual scene, with no need to invoke an upper limit on the number of objects represented.

The Role of Working Memory in Dual-Target Visual Search

Frontiers in Psychology

Visual search (VS) for multiple targets is especially error prone. One of these errors is called subsequent search misses (SSM) and represents a decrease in accuracy at detecting a second target after a first target has been found. One of the possible explanations of SSM errors is working memory (WM) resource depletion. Three experiments investigated the role of WM in SSM errors using a dual task paradigm. The first experiment investigated the role of object WM using a classical color change detection task. In the second and the third experiments, a modified change detection task was applied, using shape as the relevant feature. The results of our study revealed no effect of additional WM task on second target detection in dual-target VS. To this end, SSM errors are not related to WM resource depletion. On the contrary, WM task performance was violated by dual-target VS as compared to single-target VS, when the targets in VS task were defined by the same feature used in the WM task.

Finding memory in search: The effect of visual working memory load on visual search

2010

There is now substantial evidence that during visual search, previously searched distractors are stored in memory to prevent them from being re-selected. Studies examining which memory resources are involved in this process have indicated that while a concurrent spatial working memory task does affect search slopes, depleting visual working memory (VWM) resources does not. In the present study, we confirm that VWM load indeed has no effect on the search slope, however, there is an increase in overall reaction times that is directly related to the number of items held in VWM. Importantly, this effect on search time increases proportionally with the memory load until the capacity of VWM is reached. Furthermore, the search task interfered with the number of items stored in VWM during the concurrent change-detection task. These findings suggest that VWM plays a role in the inhibition of previously searched distractors.

The role of working memory and long-term memory in visual search

Models of attentional deployment in visual search commonly specify that the shortterm, or working memory, system plays a central role in biasing attention mechanisms to select task relevant information. In contrast, the role of long-term memory in guiding search is rarely articulated. Our review of recent studies calls for the need to revisit how existing models explain the role of working memory and long-term memory in search. First, the role of working memory in guiding attentional selection and search is much more complex than many current theories propose. Second, both explicit and implicit long-term memory representations have such clear influences on visual search performance that they deserve more prominent treatment in theoretical models. These new findings in the literature should stir the conception of new models of visual search.

Visual Working Memory Resources Are Best Characterized as Dynamic, Quantifiable Mnemonic Traces

Topics in Cognitive Science, 2017

Visual working memory (VWM) is a construct hypothesized to store a small amount of accurate perceptual information that can be brought to bear on a task. Much research concerns the construct's capacity and the precision of the information stored. Two prominent theories of VWM representation have emerged: slot-based and continuous-resource mechanisms. Prior modeling work suggests that a continuous resource that varies over trials with variable capacity and a potential to make localization errors best accounts for the empirical data. Questions remain regarding the variability in VWM capacity and precision. Using a novel eye-tracking paradigm, we demonstrate that VWM facilitates search and exhibits effects of fixation frequency and recency, particularly for prior targets. Whereas slot-based memory models cannot account for the human data, a novel continuous-resource model does capture the behavioral and eye tracking data, and identifies the relevant resource as item activation.

Effects of individual differences on visual search task performance

PsycEXTRA Dataset, 2000

Working memory capacity (WMC) is generally referred to as a quantitative measure of the ability to maintain relevant information while performing unrelated tasks . Although studies have shown that WMC can vary by individual , performance can be taxed by varying degrees of subjective workload depending on the task parameters. Most studies have shown task performance benefits for individuals with high working memory capacity, with some exceptions for individuals with low working memory capacity . Kane and colleagues (2006) tested the relationship of WMC and executive attention control and found no relationship with individual differences in WMC and performance on visual search tasks, namely on feature-absence, conjunction, and spatial configuration search tasks. However, other studies have found that loading

An assessment of fixed-capacity models of visual working memory

Proceedings of the National Academy of Sciences of the United States of America, 2008

Visual working memory is often modeled as having a fixed number of slots. We test this model by assessing the receiver operating characteristics (ROC) of participants in a visual-working-memory change-detection task. ROC plots yielded straight lines with a slope of 1.0, a tell-tale characteristic of all-or-none mnemonic representations. Formal model assessment yielded evidence highly consistent with a discrete fixed-capacity model of working memory for this task.

Looking sharp: Becoming a search template boosts precision and stability in visual working memory

Attention, perception & psychophysics, 2017

Visual working memory (VWM) plays a central role in visual cognition, and current work suggests that there is a special state in VWM for items that are the goal of visual searches. However, whether the quality of memory for target templates differs from memory for other items in VWM is currently unknown. In this study, we measured the precision and stability of memory for search templates and accessory items to determine whether search templates receive representational priority in VWM. Memory for search templates exhibited increased precision and probability of recall, whereas accessory items were remembered less often. Additionally, while memory for Templates showed benefits when instances of the Template appeared in search, this benefit was not consistently observed for Accessory items when they appeared in search. Our results show that becoming a search template can substantially affect the quality of a representation in VWM.