Academic journal article Attention, Perception and Psychophysics

Different Developmental Trajectories across Feature Types Support a Dynamic Field Model of Visual Working Memory Development

Academic journal article Attention, Perception and Psychophysics

Different Developmental Trajectories across Feature Types Support a Dynamic Field Model of Visual Working Memory Development

Article excerpt

Published online: 4 March 2015

© The Psychonomic Society, Inc. 2015

Abstract Research on visual working memory has focused on characterizing the nature of capacity limits as "slots" or "resources" based almost exclusively on adults' performance with little consideration for developmental change. Here we argue that understanding how visual working memory develops can shed new light onto the nature of representations. We present an alternative model, the Dynamic Field Theory (DFT), which can capture effects that have been previously attributed either to "slot" or "resource" explanations. The DFT includes a specific developmental mechanism to account for improvements in both resolution and capacity of visual working memory throughout childhood. Here we show how development in the DFT can account for different capacity estimates across feature types (i.e., color and shape). The current paper tests this account by comparing children's (3, 5, and 7 years of age) performance across different feature types. Results showed that capacity for colors increased faster over development than capacity for shapes. A second experiment confirmed this difference across feature types within subjects, but also showed that the difference can be attenuated by testing memory for less familiar colors. Model simulations demonstrate how developmental changes in connectivity within the model-purportedly arising through experience-can capture differences across feature types.

Keywords Visual working memory . Capacity . Neural network model . Development . Change detection

A well-known characteristic of visual working memory (VWM) is its limited capacity (estimated to be three to five simple objects; Cowan, 2001), but the nature of this limitation has been a source of considerable debate. The focus of this debate has been on whether slot-like, fixed-resolution representations (e.g., Zhang & Luck, 2008), or the allocation of a limited resource pool with decreasing resolution per item as the number of items increases (e.g., Bays & Husain, 2008), provides a more complete account of performance in laboratory tasks. Although dozens of studies have been published and some empirical support has been found for each approach, as well as for some hybrid approaches (e.g., Alvarez & Cavanagh, 2004;Xu&Chun,2006) , the debate has not yet been resolved.

In this paper, we argue that an important dimension in this debate that has been largely ignored is the nature of developmental change. Specifically, we propose that understanding how capacity increases over development will shed light onto the nature of the underlying VWM representations. Empirical studies have demonstrated improvements in working memory with age, but few theories have proposed specific mechanisms that underlie developmental increases in capacity (see Simmering & Perone, 2013, for review). The source of developmental changes in VWM has important implications not only for understanding how VWM functions in adults, but also for potential insight into atypical populations who show deficits in VWM (e.g., with schizophrenia and attention-deficit/hyperactivity disorder (Karatekin & Asarnow, 1998), or following preterm birth (Luciana, Lindeke, Georgieff, Mills, & Nelson, 1999)). Furthermore, studies on working memory training suggest that earlier interventions may be more beneficial (Wass, Scerif, & Johnson, 2012), but that we need a better understanding of how working memory functions and develops to create effective interventions (e.g., Shipstead, Hicks, & Engle, 2012).

In the sections that follow, we first review how VWM develops and the theories that have been put forth to explain both capacity and development. Next, we present the Dynamic Field Theory (DFT) as an alternative model to the dominant slots and resources perspectives (Johnson & Simmering, in press; Johnson, Simmering, & Buss, 2014). The DFT incorporates a specific developmental mechanism that can account for developmental improvements in both capacity (Perone, Simmering, & Spencer, 2011; Simmering, 2008, 2015)and resolution (Simmering & Patterson, 2012) of color memory. …

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