Interaction between object-based attention and pertinence values shapes the attentional priority map of a multielement display

Abstract

Previous studies have shown that the perceptual organization of the visual scene constrains the deployment of attention. Here we investigated how the organization of multiple elements into larger configurations alters their attentional weight, depending on the "pertinence" or behavioral importance of the elements' features. We assessed object-based effects on distinct aspects of the attentional priority map: top-down control, reflecting the tendency to encode targets rather than distracters, and the spatial distribution of attention weights across the visual scene, reflecting the tendency to report elements belonging to the same rather than different objects. In 2 experiments participants had to report the letters in briefly presented displays containing 8 letters and digits, in which pairs of characters could be connected with a line. Quantitative estimates of top-down control were obtained using Bundesen's Theory of Visual Attention (1990). The spatial distribution of attention weights was assessed using the "paired response index" (PRI), indicating responses for within-object pairs of letters. In Experiment 1, grouping along the task-relevant dimension (targets with targets and distracters with distracters) increased top-down control and enhanced the PRI; in contrast, task-irrelevant grouping (targets with distracters) did not affect performance. In Experiment 2, we disentangled the effect of target-target and distracter-distracter grouping: Pairwise grouping of distracters enhanced top-down control whereas pairwise grouping of targets changed the PRI. We conclude that object-based perceptual representations interact with pertinence values (of the elements' features and location) in the computation of attention weights, thereby creating a widespread pattern of attentional facilitation across the visual scene. (PsycINFO Database Record

Figure 1

Experimental paradigm. (a) Outline of a single trial showing the timing of the different events. (b) Experiment 1: Illustration of the five different display types used: eight target letters not grouped or grouped by connectedness (top row), four targets intermixed with four distracters either not grouped, or grouped according to task relevance, or each target grouped with a distracter (bottom row). (c) Experiment 2: Illustration of the six different display types used: eight target letters not grouped or grouped by connectedness (top row, first two columns), four targets intermixed with four distracters either not grouped, or grouped according to task relevance (bottom row, first two columns), four targets intermixed with four distracters where either the targets are grouped (top row, last column) or the distracters are grouped (bottom row, last column).

Figure 2

Computational modeling of behavioral data. The number of correctly reported letters in the 8T no grouping conditions from two representative participants illustrating the relationship between the raw data and the TVA-based parameters. In addition to the observed data (black triangles), the scores predicted by the TVA model are plotted (solid black line) to indicate that the model is a good fit to the data and to illustrate how K (the asymptotic level of the curve), t₀ (the exposure durations at which the curve rises from the abscissa), and C parameters (the slope of the curves at t₀) are related to these scores. TVA = Theory of Visual Attention.

Figure 3

Experiment 1: correctly reported letters. (a) Whole report performance showing the mean number of correctly reported letters as a function of exposure duration in the whole report trials without grouping. Error bars represent SEM. (b-c) Mean number of correctly reported letters in the whole report (b) and partial report (c) trials, as a function of exposure duration and grouping condition. Error bars represent SEM.

Figure 4

Experiment 1: paired response index. Paired response index in the whole report (b) and partial report (c) trials, as a function of exposure duration and grouping condition. The paired response index reflects the average number of correctly reported pairs of letters, corrected for what would be expected by chance. Error bars represent SEM.

Figure 5

Experiment 2: correctly reported letters. Mean number of correctly reported letters in the whole report (a) and partial report (b) trials, as a function of exposure duration and grouping condition. Error bars represent SEM.

Figure 6

Experiment 2: paired response index. Paired response index in the whole report (a) and partial report (b) trials, as a function of exposure duration and grouping condition. The paired response index reflects the average number of correctly reported pairs of letters, corrected for what would be expected by chance. Error bars represent SEM.