scholarly journals When “capacity” changes with set size: Ensemble representations support the detection of across-category changes in visual working memory

2019 ◽  
Vol 19 (5) ◽  
pp. 3 ◽  
Author(s):  
Mark W. Schurgin ◽  
Timothy F. Brady
Keyword(s):  
Working Memory ◽  
Visual Working Memory ◽  
Set Size ◽  
Ensemble Representations

scholarly journals Integration of ensemble representations stored in visual working memory

2017 ◽  
Vol 17 (10) ◽  
pp. 116
Author(s):  
Jifan Zhou ◽  
Yijun Zhang ◽  
Shulin Chen ◽  
Rende Shui ◽  
Mowei Shen
Keyword(s):  
Working Memory ◽  
Visual Working Memory ◽  
Ensemble Representations

scholarly journals Auditory and Visual Working Memory Are Differentially Related to Carotenoid Status in Preadolescent Children

2020 ◽  
Vol 4 (Supplement_2) ◽  
pp. 98-98
Author(s):  
Corinne Cannavale ◽  
Caitlyn Edwards ◽  
Ruyu Liu ◽  
Samantha Iwinski ◽  
Anne Walk ◽  
...  
Keyword(s):  
Working Memory ◽  
Visual Working Memory ◽  
Cognitive Abilities ◽  
Memory Function ◽  
Memory Task ◽  
Whole Body ◽  
Set Size ◽  
Preadolescent Children ◽  
Central Illinois ◽  
The Relationship

Abstract Objectives Carotenoids are plant pigments known to deposit in neural tissues including the hippocampus, a brain substrate that supports several memory forms. However, there is a dearth of knowledge regarding carotenoid status and working memory function in children. Accordingly, this study aimed to understand the relationship between macular and skin carotenoids to visual and auditory working memory (WM) function. Methods Seventy preadolescent children (7–12 years, 32 males) were recruited from the East-Central Illinois area. Auditory working memory was assessed using the story recall subtest of the Woodcock-Johnson IV Test of Cognitive Abilities. A subsample (N = 61, 27 males) completed a visual working memory task and reaction time was quantified to determine speed of memory processing at set sizes of 1 to 4 items. Macular pigment optical density (MPOD) was assessed using customized heterochromatic flicker photometry. Skin carotenoids were assessed using reflection spectroscopy (Veggie Meter). Hierarchical linear regressions were conducted to assess the relationship between carotenoid status and WM function, while controlling for age, sex, income, and whole-body % fat (DXA). Results Auditory WM was positively associated with skin carotenoids (b = 0.263, P = 0.039) but not MPOD (b = −0.044, P = 0.380). In contrast, MPOD was significantly associated with faster visual WM speed at set size 3 (b = −0.253, P = 0.039) and trending at set sizes of 1 (b = −0.225, P = 0.051), 2 (b = −0.171, P = 0.121), and 4 (b = −0.230, P = 0.055). Interestingly, skin carotenoids were not related to visual WM performance at either set size (all P’s > 0.300). Conclusions These results indicate that auditory and visual WM may be differentially related to carotenoids. While skin carotenoids encompass all carotenoids consumed in diet, lutein and zeaxanthin are the only carotenoids which deposit in the macula. Given that MPOD was only related to visual WM, this suggests lutein plays a larger role in these neural functions relative to auditory WM. Interestingly, MPOD's relationship with visual WM increased in strength with the more difficult trial type (i.e., increasing set size), indicating MPOD is related at higher levels of WM capacity. Funding Sources This study was funded by the Egg Nutrition Center.

scholarly journals Induced and Evoked Human Electrophysiological Correlates of Visual Working Memory Set-Size Effects at Encoding

PLoS ONE ◽  
2016 ◽  
Vol 11 (11) ◽  
pp. e0167022 ◽  
Author(s):  
Gennadiy Gurariy ◽  
Kyle W. Killebrew ◽  
Marian E. Berryhill ◽  
Gideon P. Caplovitz
Keyword(s):  
Working Memory ◽  
Visual Working Memory ◽  
Size Effects ◽  
Set Size ◽  
Set Size Effects

scholarly journals When “capacity” changes with set size: Ensemble representations support the detection of across-category changes in visual working memory

2018 ◽  
Author(s):  
Mark Schurgin ◽  
Timothy F. Brady
Keyword(s):  
Working Memory ◽  
Memory Performance ◽  
Working Memory Capacity ◽  
Limited Resource ◽  
Fixed Number ◽  
Stimulus Similarity ◽  
Set Size ◽  
Complex Stimuli ◽  
Potential Use ◽  
Ensemble Representations

Is there a fixed limit on how many objects we can hold actively in mind? Generally, researchers have found participants are able to remember fewer objects if they are more complex, suggesting a limited resource rather than a fixed number of objects best explains working memory performance. However, some evidence has suggested that stimulus similarity better accounts for these effects, and that after accounting for such similarity, the data support a slot-based fixed- item limit for working memory. Much of the evidence used to support the latter claim relies on working memory displays containing different categories of items. It has been found that for large, across-category changes, performance does not differ for different kinds of complex stimuli. However, many of these studies fail to adequately control for the potential use of ensemble information in discriminating such large, across-category changes. Here, we sought to identify how much ensemble representations may explain performance across these tasks. In Experiment 1, we observed that as set size increased from 4 to 12 items, capacity estimates for across-category changes increased linearly as well, providing evidence against the claim of a fixed capacity. In Experiment 2, we controlled for stimulus complexity and similarity but varied the utility of ensemble representations for the change detection task. We observed significantly greater capacity when ensemble information could be used. Altogether, these results are contrary to a slot-like, fixed-object constraint on working memory capacity, and consistent with object complexity and ensemble representations strongly affecting working memory performance.

scholarly journals Is categorization in visual working memory a way to reduce mental effort? A pupillometry study

2021 ◽  
Author(s):  
Cherie Zhou ◽  
Monicque M. Lorist ◽  
Sebastiaan Mathot
Keyword(s):  
Working Memory ◽  
Visual Working Memory ◽  
Visual Information ◽  
Pupil Size ◽  
Mental Effort ◽  
Pupil Dilation ◽  
General Category ◽  
Set Size ◽  
Memory Precision ◽  
Continuous Representations

Recent studies on visual working memory (VWM) have shown that visual information can be stored in VWM as continuous (e.g., a specific shade of red) as well as categorical representations (e.g., the general category red). It has been widely assumed, yet never directly tested, that continuous representations require more VWM mental effort than categorical representations; given limited VWM capacity, this would mean that fewer continuous, as compared to categorical, representations can be maintained simultaneously. We tested this assumption by measuring pupil size, as a proxy for mental effort, in a delayed estimation task. Participants memorized one to four ambiguous (boundaries between adjacent color categories) or prototypical colors to encourage continuous or categorical representations, respectively; after a delay, a probe indicated the location of the to-be-reported color. We found that, for set size 1, pupil size was larger while maintaining ambiguous as compared to prototypical colors, but without any difference in memory precision; this suggests that participants relied on an effortful continuous representation to maintain a single ambiguous color, thus resulting in pupil dilation while preserving precision. In contrast, for set size 2 and higher, pupil size was equally large while maintaining ambiguous and prototypical colors, but memory precision was now substantially reduced for ambiguous colors; this suggests that participants now also relied on categorical representations for ambiguous colors (which are by definition a poor fit to any category), thus reducing memory precision but not resulting in pupil dilation. Taken together, our results suggest that continuous representations are more effortful than categorical representations, and that very few continuous representations (perhaps only one) can be maintained simultaneously.

scholarly journals Is set size six really set size six? Relational coding in visual working memory.

2019 ◽  
Vol 19 (10) ◽  
pp. 134a
Author(s):  
Chaipat Chunharas ◽  
Timothy F Brady
Keyword(s):  
Working Memory ◽  
Visual Working Memory ◽  
Set Size

scholarly journals Seeing Both the Forest and the Trees: Distinct Resolution of Hierarchical Representations in Visual Working Memory

2019 ◽  
Author(s):  
Tina Tong Liu ◽  
Zhongting Chen ◽  
Matt Oxner ◽  
Wanying Wang ◽  
Yixuan Ku ◽  
...  
Keyword(s):  
Working Memory ◽  
Visual Working Memory ◽  
Empirical Data ◽  
Present Series ◽  
Hierarchical Bayesian Models ◽  
Set Size ◽  
Capacity Limit ◽  
Item Level ◽  
Flexible Resource ◽  
Hierarchical Representations

The capacity limit in visual working memory (VWM) has been well established, but the way in which it is limited remains under debate. For example, an item limit was proposed by the discrete slot models whereas a flexible allocation of information was suggested by the flexible resource models. Despite the discrepancies on the nature of VWM capacity limit, both models assume that items are processed independently. Recent evidence, however, revealed that VWM is hierarchically structured. Given that an item can be represented both at the ensemble and the item level, existing measures of VWM capacity cannot distinguish between them. To separately measure an item at both ensemble and item levels, we designed a novel paradigm by combining the continuous report paradigm with a categorical judgement task. In the present series of four experiments, we found that participants’ performance at the ensemble and the item level was differentially affected by the layout and the number of objects in the display. Similarly, hierarchical Bayesian models fit to the empirical data suggest distinct effects of layout and set size on ensemble and item representations, respectively. Moreover, separating ensemble from item representations further allowed us to address their relationship and we uncovered a surprising possibility of independence between these two levels of representations. Taken together, the present dissociation and the demonstration of independence suggest distinct mechanisms of item and ensemble processing, which further sheds light on the nature and structure of representations in VWM.

scholarly journals A resource-rational theory of set size effects in visual working memory

2017 ◽  
Author(s):  
Ronald van den Berg ◽  
Wei Ji Ma
Keyword(s):  
Working Memory ◽  
Visual Working Memory ◽  
Size Effects ◽  
Cost Minimization ◽  
Normative Theory ◽  
Neural Encoding ◽  
Set Size ◽  
Cognitive Limitations ◽  
Set Size Effects ◽  
The Brain

AbstractEncoding precision in visual working memory decreases with the number of encoded items. Here, we propose a normative theory for such set size effects: the brain minimizes a weighted sum of an error-based behavioral cost and a neural encoding cost. We construct a model from this theory and find that it predicts set size effects. Notably, these effects are mediated by probing probability, which aligns with previous empirical findings. The model accounts well for effects of both set size and probing probability on encoding precision in nine delayed-estimation experiments. Moreover, we find support for the prediction that the total amount of invested resource can vary non-monotonically with set size. Finally, we show that it is sometimes optimal to encode only a subset or even none of the relevant items in a task. Our findings raise the possibility that cognitive “limitations” arise from rational cost minimization rather than from constraints.

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