Template-to-distractor distinctiveness regulates visual search efficiency

Abstract

All models of attention include the concept of an attentional template (or a target or search template). The template is conceptualized as target information held in memory that is used for prioritizing sensory processing and determining if an object matches the target. It is frequently assumed that the template contains a veridical copy of the target. However, we review recent evidence showing that the template encodes a version of the target that is adapted to the current context (e.g. distractors, task, etc.); information held within the template may include only a subset of target features, real world knowledge, pre-existing perceptual biases, or even be a distorted version of the veridical target. We argue that the template contents are customized in order to maximize the ability to prioritize information that distinguishes targets from distractors. We refer to this as template-to-distractor distinctiveness and hypothesize that it contributes to visual search efficiency by exaggerating target-to-distractor dissimilarity.

Figure 1:

A) A cartoon illustration of how template information is shaped by learned expectations about the search context and impacts sensory processing. The target is the pink circle within the search displays. Multiple search displays over time contribute to the learned expectations of distractor properties. Because the target appears with “bluer” distractors, the template encodes a “redder” target than veridical. This produces larger “top-down” gain enhancements and sensory responses that prioritize the off-veridical “reddish” color over the true target “pinkish” color. Despite being slightly off-veridical, the shift in the template is advantageous because it prioritizes target features that are more distinct from distractors. B) Illustration of the representational geometry of the target template and different objects in the visual display. All four relationships (labeled 1–4) are important for predicting visual search efficiency. The specific geometry here is just an illustrative case of the more general thesis that the target template is rarely an exact replica of the searched-for target, and instead, an adapted version that accentuates information that best differentiates the target from distractors. The specific geometry (illustrated distances 1–4) are expected to change according to stimulus context and task goals.