Nonlinear effects of spatial connectedness implicate hierarchically structured representations in visual working memory

Błażej Skrzypulec,Adam Chuderski

doi:10.1016/j.jml.2020.104124

Abstract

• Spatial connectedness non-linearly influences performance in change detection task. • Heterogeneity of stimulus structure hinders Visual Working Memory performance. • Representations in Visual Working Memory possess hierarchical part/whole structure. Five experiments investigated the role of spatial connectedness between a pair of objects presented in the change detection task for the actual capacity of visual working memory (VWM) in healthy young adults (total N = 405). Three experiments yielded a surprising nonlinear relationship between the proportion of pair-wise connected objects and capacity, with the highest capacity observed for homogenous displays, when either all objects were connected or disjointed. A drop in capacity, ranging from an average of a quarter of an object out of three objects maintained in VWM, was noted when only some objects were connected while others were disjointed. As indicated by another two experiments, this effect was specific to double-feature encoding, but disappeared when single visual features had to be memorized. No existing theoretical model of VWM can directly explain this novel effect. Overall, the nonlinear effect of spatial connectedness implies that representations in VWM possess hierarchical structure defined by wholes, parts, features, and their relations, and the heterogeneity of such a structure hinders VWM performance, while homogeneity facilitates it.

Highlights

Effective visual perception of the environment is a fundamental cognitive faculty, providing input for numerous other mental functions such as categorization, imagery, learning, memory, decision making, and action
The standard experimental paradigm used to study the limits of Visual Working Memory (VWM), called change detection task (Phillips, 1974), consists of successively presenting two patterns of objects such that either the second pattern is identical to the first or both patterns differ with respect to just a single object
Later studies have complicated our understanding of the mechanisms and representations underlying VWM capacity, more comprehensively investigating the various characteristics of to-be-detected objects beyond their sheer number

Summary

Introduction

Effective visual perception of the environment is a fundamental cognitive faculty, providing input for numerous other mental functions such as categorization, imagery, learning, memory, decision making, and action. That included the objects’ features (Bays, Wu, & Husain, 2011), spatial relations (Woodman, Vecera, & Luck, 2003), and context (Clevenger & Hummel, 2013), as well as the reproduction of certain information (Wilken & Ma, 2004). These studies’ findings resulted in several competing models of VWM functioning (for reviews, see Brady, Konkle, & Alvarez, 2011; Luck & Vogel, 2013)

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