Academic journal article Attention, Perception and Psychophysics

Toward Ecologically Realistic Theories in Visual Short-Term Memory Research

Academic journal article Attention, Perception and Psychophysics

Toward Ecologically Realistic Theories in Visual Short-Term Memory Research

Article excerpt

Published online: 22 March 2014

© Psychonomic Society, Inc. 2014

Abstract Recent evidence from neuroimaging and psychophysics suggests common neural and representational substrates for visual perception and visual short-term memory (VSTM).Visual perception is adapted to a rich set of statistical regularities present in the natural visual environment. Common neural and representational substrates for visual perception and VSTM suggest that VSTM is adapted to these same statistical regularities too. This article discusses how the study of VSTM can be extended to stimuli that are ecologically more realistic than those commonly used in standard VSTM experiments and what the implications of such an extension could be for our current view of VSTM. We advocate for the development of unified models of visual perception and VSTM-probabilistic and hierarchical in nature-incorporating prior knowledge of natural scene statistics.

Keywords Visual short-term memory . Ecological validity . Probabilisticmodel

Introduction

Research on visual short-term memory (VSTM) generally uses artificial visual displays consisting of simple objects with easily parameterizable features and with no statistical structure within or between objects. These displays are used to address questions such as the nature of capacity limits or the units of storage in VSTM (Brady, Konkle, & Alvarez, 2011). This choice of stimuli confers many advantages to the design of experiments and to the interpretation of results obtained from such experiments. Among the advantages of using artificial and simple stimuli are the ease with which such stimuli can be generated and manipulated, the fact that they make the formulation and testing of hypotheses straightforward, their relative unfamiliarity for subjects, and, lastly, their "bare bones" character, stripped of features that are irrelevant to the hypothesis under question. The last two properties help to minimize the effects of irrelevant prior knowledge or assumptions subjects might bring to a VSTM task.

Despite these advantages, psychologists have also been aware of the potential problems that are associated with the use of artificial stimuli and tasks in experimental studies (Brunswik, 1943, 1955; Neisser, 1976). The main concern here is the danger that these stimuli and tasks might be too artificial to give an accurate reflection of the problems faced by an observer in the natural world. Given that many aspects of perception and cognition can be profitably thought of as rational solutions or adaptations to problems that observers (and actors) encounter in their natural environments (Anderson, 1990; Geisler, Perry, & Ringach, 2009), unnatural stimuli and tasks might lead to misleading characterizations of perceptual and cognitive processes.

In this article, our goal is to take a critical look at the use in VSTM studies of impoverished, unnatural scenes lacking the rich statistical structure displayed by stimuli that are more representative of the natural environment. Although we acknowledge that experiments using artificial displays with simple statistical structure are often useful first steps in elucidating fundamental perceptual and cognitive processes, we argue that whether and how results obtained from such experiments would generalize to stimuli and tasks that are more representative of the natural environment should always be considered carefully. If there are any doubts about the generalizability of the results, experimental stimuli and procedures will need to be refined accordingly. In the following sections, we discuss why we think the question of ecological validity in VSTMresearch should be takenmore seriously and how the study of VSTMcan be extended to ecologically more realistic stimuli, as well as possible implications of such an extension.

Why is it important to take the question of ecological validity in VSTM research seriously?

As was mentioned above, although the use of unnatural stimuli and tasks might afford greater experimental control, psychologists have been aware of the problems with generalizing the results of such studies (Brunswik, 1943, 1955; Neisser, 1976). …

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