Figure 5.

Illustrates the linkage between looking and learning during familiarization (A–C) and the basis for discrimination during the test phase (D–E) in the DNF model. The left y-axis shows the strength of activation in PF / WM (black line) and the right y-axis shows the strength of activation HL_PF (top panel) / HL_WM (pink line). Initially, in panel A the model is fixating the left location and the brown stimulus is being encoding (see activation peak centered at site 90 in PF). Notice that activity in HL_PF has already begun to accumulate. In panel B, the model spontaneously switches gaze to an away location at which no task relevant stimulus is present. Activity in PF subsides. In panel C, the model reacquires fixation and is looking at an identical brown stimulus at the right location. This stimulus is again input into PF and encoding is strengthened due to the accumulated activity in HL_PF (see pink line, right y-axis). Activity in WM is also starting to emerge (see black line in lower panel).

After the familiarization phase, the model enters the test phase and, like infants, is presented with the familiar stimulus and a novel stimulus. In this example, the novel stimulus is dissimilar on the color dimension. Panel D shows the state of PF and WM when the model looks at the familiar stimulus. Here, HL_WM (pink line, right y-axis) has accumulated across the familiarization phase and WM is actively maintaining a peak associated with the familiar item (black line). Consequently, PF activity generated by the familiar stimulus is strongly inhibited by WM and support for looking low. Panel E shows the state of PF and WM when the model looks at the novel stimulus. Here, the sustained WM peak associated with the familiar item continues to suppress PF activity at the familiar site. However, inhibition at sites tuned to the dissimilar novel item is minimal, PF activity strong, and support for looking is high.