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. Author manuscript; available in PMC: 2013 May 28.
Published in final edited form as: Dev Sci. 2011 Sep 17;14(6):1379–1392. doi: 10.1111/j.1467-7687.2011.01083.x

Figure 3.

Figure 3

Illustration of the mechanisms underlying change preferences and development. Panels A–E show the old infant model while looking at the no-change (A–C) and change (D–E) displays, and panels F–G show the young infant model while looking at the change display. Along the x-axis of PF and WM is the color value (in degrees). The left y-axis shows activation in PF and WM, and the right y-axis shows the Hebbian contributions to PF and WM. Initially, the old infant model is looking at the no-change display (A) and begins to encode and form WM peaks for the two items on the display. This supports fixation through activation in PF feeding excitation back to the fixation system. During the delay (B), the model is maintaining the items on the no-change display in WM. This inhibits associated neural sites in PF, which continues when the no-change display reappears (C) and leads to little support for fixation. When the model looks to the change display (D), it encodes the two items not held in memory. The related activity in PF supports fixation. When the change display reappears (E), one item has changed. The model encodes the novel item, continuing to support fixation. Note that the old model maintains items from the no-change display while looking at the change display. Stochastic looking between the two displays results in recognition of the items on the no-change display and encoding of novel items on the change display, giving rise to a change preference. For the young model, the processes of encoding items on the no-change and changes displays are comparable to the old infant model (see A–C). When the young model looks at the change display (F–G), however, the WM peaks maintaining the items from the no-change display spontaneously decay. This arises due to implementation of the Spatial Precision Hypothesis, specifically, weaker excitatory and inhibitory interactions for the young model. In contrast to the old model, the young model must re-encode items on the no-change display upon re-fixation. This leads to no preference across displays.