Task-irrelevant features can be ignored in feature-based encoding

Abstract

The present study aimed to explore whether individuals could selectively remember task-relevant features while ignoring task-irrelevant features for given items. Participants were initially asked to remember the task-relevant feature of one (low load), two (medium load), or four (high load) items, while ignoring their task-irrelevant features. Participants were required to make responses to the target in the subsequent search task, while being presented with distractors that contained either task-irrelevant or task-relevant features. No features matched with the studied items in the neutral trials. The items’ color was manipulated as a task-relevant feature in Experiment 1, while their shape was designated as a task-irrelevant feature. Conversely, the items’ shape was manipulated as a task-relevant feature in Experiment 2, and their color was designated as task-irrelevant. The event-related potentials evoked by the visual search task were also examined. The results showed that, in both experiments, 1) The response time showed no differences between task-irrelevant trials and neutral trials among different load conditions, suggesting that the task-irrelevant distractors may not slow down the target searching. 2) The magnitude of the target-elicited N2pc was similar between the neutral and the task-irrelevant trials among different load conditions, indicating that the task-irrelevant distractor received no attention and had no effect on the target processing. The results indicated that the task-irrelevant features were suppressed or completely disregarded.