Units of the Visual Working Memory Representational System

Abstract

Introduction

The capacity of working memory has been studied extensively in the past and rightfully so since it arguably represents the most crucial underpinning of an individual’s cognitive ability [1]. Visual working memory, a subsystem of working memory responsible for encoding and maintaining visual information, is a system with its own limited capacity. The characteristics of this capacity have been studied, and  two separate systems - each with its own limited capacity - have been identified. Firstly, there is the hemisphere-specific representational system, responsible for establishing visual representations and secondly, there is the activational system responsible for keeping these representations active in the working memory [2]. Furthermore, evidence suggests that maintenance of features of different visual modalities (i.e., colors and shapes) depends on a common representational system and independent activational systems. [3]. Perhaps these results may shed light on the inconclusive findings of prior studies exploring whether the units in visual working memory are individual visual features or integrated objects (objects consisting of multiple features). There is evidence supporting both claims [3]. Our aim is to provide additional insights on this dilemma by using the two-system framework.

Specifically, based on the finding that different visual features share a common representational system [3] we aim to explore whether the unit (which defines visual working memory capacity) within this system represents  an individual visual property or an integrated object.

 Method

We will use a visual working memory span task, in which participants will have to remember all the features (colors and shapes) of the stimuli presented to them. This task will have two main conditions:

• Colors and shapes will be presented in spatially separated objects (different shapes outlined in black and circles of different colors)
• Colors and shapes will be presented within integrated objects (shapes with different colors)

Results

A comparison of the capacity for both conditions will be made. If the capacity for the integrated objects condition is higher than the condition with separated objects, this will suggest that the unit of visual working memory is an integrated object. On the contrary, if there is no difference in the capacity between conditions, it is more likely the unit of visual working memory is an individual visual feature. The latter would provide further evidence for a unified representational system with limited units, each reserved for an individual feature irrespective of modality [3].

References

[1] A. Baddeley, “Working Memory: theories, models, and controversies,” Annual Review of Psychology, vol. 63, no. 1, pp. 1–29, Jan. 2012, doi: 10.1146/annurev-psych-120710-100422.

[2] A. S. Ozimič and G. Repovš, “Visual working memory capacity is limited by two systems that change across lifespan,” Journal of Memory and Language, vol. 112, p. 104090, Jun. 2020, doi: 10.1016/j.jml.2020.104090.

[3] A. Slana Ozimič, “Maintenance of individual features and integrated information in visuo-spatial working memory“, Ph. D dissertation, 2020 [Online]. Available: https://repozitorij.uni-lj.si/IzpisGradiva.php?id=117341. [accessed: May 7th, 2024.]