Stronger neural dynamics capture changes in infants’ visual working memory capacity over development

Abstract

Visual working memory (VWM) capacity has been studied extensively in adults, and methodological advances have enabled researchers to probe capacity limits in infancy using a preferential looking paradigm. Evidence suggests that capacity increases rapidly between 6 and 10 months of age. To understand how the VWM system develops, we must understand the relationship between the looking behavior used to study VWM and underlying cognitive processes. We present a dynamic neural field model that captures both real-time and developmental processes underlying performance. Three simulation experiments show how looking is linked to VWM processes during infancy and how developmental changes in performance could arise through increasing neural connectivity. These results provide insight into the sources of capacity limits and VWM development more generally.

Models provide specificity: Testing a proposed mechanism of visual working memory capacity development

“…Although the DFT has not been designed to address these questions specifically, it can be tested in different tasks to examine how broadly the SPH may generalize. For example, Perone and colleagues (2011) used the SPH in a related architecture to capture infants’ looking behavior in a task designed to measure VWM capacity during the first year. Their simulations showed that the “young” infant model could perform similarly to the “old” infant model by removing the delays between items, suggesting that one consequence of strengthening neural interactions is improved maintenance of items over delay.…”

“…Beyond the implementation of the SPH described here and used by Perone et al (2011) and Schutte and Spencer (2009), developmental changes in other dynamic neural field architectures have been used to capture behavioral development in other tasks. Buss and Spencer (2008) developed a multi-layered architecture of neural fields to perform the dimensional change card sort task, in which young children (typically 3-year-olds) have difficulty shifting rules used to sort cards.…”

“…This also highlights the importance of stability at different timescales: not only is an individual peak more susceptible to perturbation on an individual trial, but the variation in peak position and strength also varies considerably across trials early in development. Given the successful application to developmental changes in spatial cognition during early childhood (Ortmann & Schutte, 2010; Schutte & Spencer, 2009, 2010; Schutte et al, 2003; Simmering et al, 2008; Simmering & Spencer, 2008) and recent extensions to developmental changes in infant looking behavior (Perone et al, 2011; Perone & Spencer, 2011; Perone, Spencer, & Schöner, 2007), Simmering (2008) tested whether the SPH could also account for developmental increases in capacity.…”

“…A similar generalization has been shown based on Case’s hypothesis (1995; described in Section 1), in that developmental improvements in children’s speed of processing should be evident in tasks that do not measure capacity directly, and that speed of processing should correlate with performance in span tasks. Although our model seems to accomplish the same goal as Case’s theory within visual working memory research, we have the added benefit of connecting to research across a wide variety of domains using similar architectures and developmental mechanisms (e.g., Ortmann & Schutte, 2010; Perone et al, 2011; Simmering et al, 2008). Moreover, implementation of this theory in a formal model allows for exploring hypotheses within the model before testing them experimentally; the advantages of this capability are described our later discussion of how the model can address unexpected findings in our behavioral task (see Section 6).…”

“…First, it provides a test of predictions derived from the mechanism proposed to underlie developmental changes in VWM capacity. Second, it tests this developmental mechanism more generally, as a similar proposal has been shown to capture numerous other developmental phenomena in spatial cognition (e.g., Ortmann & Schutte, 2010; Perone, Simmering, & Spencer, 2011; Simmering, Schutte, & Spencer, 2008). …”