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1. Greater Visual Working Memory Capacity for Visually Matched Stimuli When They Are Perceived as Meaningful

   https://doi.org/10.1162/jocn_a_01693  

   Asp, Isabel E. ; Störmer, Viola S. ; Brady, Timothy F. ( April 2021 , Journal of Cognitive Neuroscience)

   null (Ed.)

   Abstract Almost all models of visual working memory—the cognitive system that holds visual information in an active state—assume it has a fixed capacity: Some models propose a limit of three to four objects, where others propose there is a fixed pool of resources for each basic visual feature. Recent findings, however, suggest that memory performance is improved for real-world objects. What supports these increases in capacity? Here, we test whether the meaningfulness of a stimulus alone influences working memory capacity while controlling for visual complexity and directly assessing the active component of working memory using EEG. Participants remembered ambiguous stimuli that could either be perceived as a face or as meaningless shapes. Participants had higher performance and increased neural delay activity when the memory display consisted of more meaningful stimuli. Critically, by asking participants whether they perceived the stimuli as a face or not, we also show that these increases in visual working memory capacity and recruitment of additional neural resources are because of the subjective perception of the stimulus and thus cannot be driven by physical properties of the stimulus. Broadly, this suggests that the capacity for active storage in visual working memory is not fixed but that more meaningful stimuli recruit additional working memory resources, allowing them to be better remembered. 

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2. Meaningfulness and Familiarity Expand Visual Working Memory Capacity

   https://doi.org/10.1177/09637214241262334  

   Chung, Yong_Hoon ; Brady, Timothy_F ; Störmer, Viola_S ( August 2024 , Current Directions in Psychological Science)

   Visual working memory is traditionally studied using abstract, meaningless stimuli. Although studies using such simplified stimuli have been insightful in understanding the mechanisms of visual working memory, they also potentially limit our ability to understand how people encode and store conceptually rich and meaningful stimuli in the real world. Recent studies have demonstrated that meaningful and familiar visual stimuli that connect to existing knowledge are better remembered than abstract colors or shapes, indicating that meaning can unlock additional working memory capacity. These findings challenge current models of visual working memory and suggest that its capacity is not fixed but depends on the type of information that is being remembered and, in particular, how that information connects to preexisting knowledge.

    

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3. There Is no Theory-Free Measure of “Swaps” in Visual Working Memory Experiments

   https://doi.org/10.1007/s42113-022-00150-5  

   Williams, Jamal R. ; Robinson, Maria M. ; Brady, Timothy F. ( September 2022 , Computational Brain & Behavior)

   Visual working memory is highly limited, and its capacity is tied to many indices of cognitive function. For this reason, there is much interest in understanding its architecture and the sources of its limited capacity. As part of this research effort, researchers often attempt to decompose visual working memory errors into different kinds of errors, with different origins. One of the most common kinds of memory error is referred to as a “swap,” where people report a value that closely resembles an item that was not probed (e.g., an incorrect, non-target item). This is typically assumed to reflect confusions, like location binding errors, which result in the wrong item being reported. Capturing swap rates reliably and validly is of great importance because it permits researchers to accurately decompose different sources of memory errors and elucidate the processes that give rise to them. Here, we ask whether different visual working memory models yield robust and consistent estimates of swap rates. This is a major gap in the literature because in both empirical and modeling work, researchers measure swaps without motivating their choice of swap model. Therefore, we use extensive parameter recovery simulations with three mainstream swap models to demonstrate how the choice of measurement model can result in very large differences in estimated swap rates. We find that these choices can have major implications for how swap rates are estimated to change across conditions. In particular, each of the three models we consider can lead to differential quantitative and qualitative interpretations of the data. Our work serves as a cautionary note to researchers as well as a guide for model-based measurement of visual working memory processes.

    

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4. The locus of recognition memory signals in human cortex depends on the complexity of the memory representations

   https://doi.org/10.1093/cercor/bhad248  

   Sanders, D_Merika_W ; Cowell, Rosemary_A ( July 2023 , Cerebral Cortex)

   According to a “Swiss Army Knife” model of the brain, cognitive functions such as episodic memory and face perception map onto distinct neural substrates. In contrast, representational accounts propose that each brain region is best explained not by which specialized function it performs, but by the type of information it represents with its neural firing. In a functional magnetic resonance imaging study, we asked whether the neural signals supporting recognition memory fall mandatorily within the medial temporal lobes (MTL), traditionally thought the seat of declarative memory, or whether these signals shift within cortex according to the content of the memory. Participants studied objects and scenes that were unique conjunctions of pre-defined visual features. Next, we tested recognition memory in a task that required mnemonic discrimination of both simple features and complex conjunctions. Feature memory signals were strongest in posterior visual regions, declining with anterior progression toward the MTL, while conjunction memory signals followed the opposite pattern. Moreover, feature memory signals correlated with feature memory discrimination performance most strongly in posterior visual regions, whereas conjunction memory signals correlated with conjunction memory discrimination most strongly in anterior sites. Thus, recognition memory signals shifted with changes in memory content, in line with representational accounts.

    

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5. Understanding Nature and Its Cognitive Benefits

   https://doi.org/10.1177/0963721419854100  

   Schertz, Kathryn E. ; Berman, Marc G. ( May 2019 , Current Directions in Psychological Science)

   Many people have the intuition that interacting with natural environments benefits their psychological health. But what has research actually demonstrated about the benefits of nature experience and the potential mechanisms underlying those benefits? This article describes empirical research on the cognitive benefits of interacting with natural environments and several theories that have been proposed to explain these effects. We also propose future directions that may be useful in exploring the extent of nature’s effects on cognitive performance and some potential mediating factors. Specifically, exposure to a variety of natural stimuli (vs. urban stimuli) consistently improves working memory performance. One potential mechanism for this is the perception of low-level features of natural environments, such as edge density in the visual domain. Although low-level features have been shown to carry semantic information and influence behavior, additional studies are needed to indicate whether perceiving these features in isolation is necessary or sufficient for obtaining the cognitive benefits of interacting with nature. 

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