Testing predictions of a neural process model of visual attention in infancy across competitive and non-competitive contexts

Abstract

A key question in early development is how changes in neural systems give rise to changes in infants' behavior. We examine this question by testing predictions of a dynamic field (DF) model of infant spatial attention. We tested 5-, 7-, and 10-month-old infants in the Infant Orienting With Attention (IOWA) task containing the original non-competitive cue conditions (when a central stimulus disappeared before a cue onset) and new competitive cue conditions (when a central stimulus remained visible throughout the trial). This allowed testing of five model predictions: (1) that orienting accuracy would be higher and (2) reaction times would be slower for all competitive conditions; (3) that all infants would be slower to orient in the competitive conditions, though (4) older infants would show the strongest competition costs; and (5) that reaction times would be particularly slow for un-cued competitive conditions. Four of these five predictions were supported, and the remaining prediction was supported in part. We next examined fits of the model to the expanded task. New simulation results reveal close fits to the present findings after parameter modification. Critically, developmental parameters of the model were not altered, providing support for the DF model's account of neuro-developmental change.

Keywords: cognitive development; dynamic field theory; infancy; neural process models; orienting attention; spatial attention.

FIGURE 1

Predictions of the 2015 DF model. These simulated data show non‐competitive (dashed lines) and competitive (solid lines) versions of the IOWA task, separated by age group. Top panels show simulated model results for reaction times on correct trials, and lower panels show overall accuracy. Columns show results for 5‐ (left), 7‐ (middle), and 10‐month‐old (right) models across the differing cue conditions (for condition details, see text and Figures 2 and 3). Simulated results for the non‐competitive task accurately captured empirical findings from Ross‐Sheehy et al. (2015). Model predictions for the competitive task are tested in the current study

FIGURE 2

The non‐competitive conditions. A central fixation stimulus (the smiley face) squished and morphed in shape until the infant attended, followed by the presentation of a visual cue (the small black dot) paired with a tone, for 100 ms. The screen was then blank for 100 ms before the target stimulus (a picture of an everyday item) appeared. The target was presented until a look was made toward the right or left or until 2,000 ms had passed. All of the conditions are shown, including valid trials in which the cue and target appeared on the same side of the monitor, invalid trials in which the cue and target appeared on opposite sides, and double cue trials in which two cues appeared simultaneously to the right and left. Baseline conditions include tone trials in which the spatially uninformative tone was played without a visual cue, and no cue trials with no visual cue and no auditory stimulus prior to the target presentation. This figure was reproduced from Ross‐Sheehy et al. (2015)

FIGURE 3

The competitive conditions. A central fixation stimulus (the smiley face) was presented throughout the entire trial. The smiley face squished and morphed in shape until the onset of the trial, and after that point, it was static. As in the non‐competitive conditions, the cue and tone were presented for 100 ms, followed by a 100‐ms blank interval and then by the target stimulus. The target remained visible until a look was made to the right or left or until 2,000 ms had passed

FIGURE 4

Infant data from the behavioral study. Infant data for non‐competitive (dashed lines) and competitive (solid lines) versions of the IOWA task, separated by age group. Top panels show infants' reaction times on correct trials, and lower panels show overall accuracy. Columns show results for 5‐ (left), 7‐ (middle), and 10‐month‐old (right) infants across the differing cue conditions (for condition details, see text and Figures 2 and 3). Cue types are indicated along the x‐axis. Error bars show the mean standard error

FIGURE 5

Competition by age group interaction. The graph shows differences in mean reaction times between the non‐competitive (dashed line) and competitive (solid line) conditions for 5‐month‐old (left), 7‐month‐old (middle), and 10‐month‐old infants (right). Error bars show the mean standard error

FIGURE 6

Competition by cue type interaction. The graph shows differences in mean reaction times between the non‐competitive (dashed line) and competitive conditions (solid line) across the different cue types (x‐axis). Error bars show the mean standard error

FIGURE 7

Neural processes that underlie performance of the present DF model. Panels a–d show the model in the invalid condition of the non‐competitive task. Panels e–f (blue rectangle) show the model during the cue (e) and target presentation (f) in the competitive task. The top layer in each panel shows the horizontal input (the white region indicates input size). The second layer in each panel shows the attention field. The blue line shows activation (y‐axis) over the horizontal spatial dimension (x‐axis) with 0 at the fovea. The green line shows the input to the attention field (which mimics the top layer). The two triangles near the fovea show the fixation node (above threshold in a) and the gaze change node (above threshold in b). Lower layers show the saccade motor field. Different panels show the following events: fixation stimulus (a), cue presentation (and no fixation stimulus) (b), target presentation (c), saccade peak formation (d), cue presentation (and continued fixation input) in the competitive task, target presentation (and continued fixation input) in the competitive task. Red ovals highlight activation differences during cue and target presentation in the non‐competitive and competitive task (see text for details)

FIGURE 8

The final simulations overlaid with the present empirical data. Reaction times during correct trials (top panel) and rates of accuracy (bottom panel) are shown for the non‐competitive (dashed lines) and competitive (solid lines) conditions. The left panel shows 5‐month‐old data and simulations, the middle panel shows 7‐month‐old data and simulations, and the right panel shows 10‐month‐old data and simulations. Empirical results are shown in red with filled in circles, while model simulations are shown in gray with open circles