The objects of visuospatial short-term memory: Perceptual organization and change detection.

Atanaska Nikolova,Bill Macken

doi:10.1080/17470218.2015.1083595

Abstract

We used a colour change-detection paradigm where participants were required to remember colours of six equally spaced circles. Items were superimposed on a background so as to perceptually group them within (a) an intact ring-shaped object, (b) a physically segmented but perceptually completed ring-shaped object, or (c) a corresponding background segmented into three arc-shaped objects. A nonpredictive cue at the location of one of the circles was followed by the memory items, which in turn were followed by a test display containing a probe indicating the circle to be judged same/different. Reaction times for correct responses revealed a same-object advantage; correct responses were faster to probes on the same object as the cue than to equidistant probes on a segmented object. This same-object advantage was identical for physically and perceptually completed objects, but was only evident in reaction times, and not in accuracy measures. Not only, therefore, is it important to consider object-level perceptual organization of stimulus elements when assessing the influence of a range of factors (e.g., number and complexity of elements) in visuospatial short-term memory, but a more detailed picture of the structure of information in memory may be revealed by measuring speed as well as accuracy.

Highlights

We used a colour change-detection paradigm where participants were required to remember colours of six spaced circles
The role of object formation needs to be examined in a setting where comparison amongst different object-level conditions can be made without potential confounds from number or spatial arrangement of stimulus elements. Another issue that we address here relates to precisely how the information represented in Visuospatial short-term memory (VSTM) is measured, since while cueing paradigms in the visual selection literature typically measure reaction time, VSTM tasks more commonly measure accuracy of same/different judgements
The current study examined the influence of perceptual object formation in VSTM, in a cueing colour change-detection paradigm, while keeping the amount and complexity of visual information in the display as constant as possible across different object-level organizations

Summary

Introduction

We used a colour change-detection paradigm where participants were required to remember colours of six spaced circles. Reaction times for correct responses revealed a same-object advantage; correct responses were faster to probes on the same object as the cue than to equidistant probes on a segmented object This same-object advantage was identical for physically and perceptually completed objects, but was only evident in reaction times, and not in accuracy measures. VSTM is associated with maintaining and processing visual and spatial information when that information is no longer present in the immediate surroundings, so it serves a critical function in the construction and maintenance of an integrated representation of the visual world (Prime, Vesia, & Crawford, 2011) The properties of this system, especially with respect to its capacity, are commonly investigated using the change detection paradigm, which involves brief presentation of a to-be-remembered display, followed by a retention period, followed by a probe display.

Methods

Results

Conclusion