When Irrelevant-Feature Priming Fails: Encoding Failure or Failure to Guide Attention?

We tend to prioritize features and locations that have recently received our attention. Surprisingly, even irrelevant features of recently attended targets enjoy increased priority. However, such irrelevant-feature priming was found for some features and not for others. Here, we inquired whether the fact that irrelevantfeature priming is sometimes absent results from a failure of encoding or from a failure of attentional guidance. To answer this question, we relied on a finding common to the visual search and attentional-control literature: when a stimulus is responded to, the features andmotor response associatedwith the action event are bound in a common representation and can be later retrieved. In two experiments, some participants searched for a color target and others for a shape target—with shape and color serving as the target’s irrelevant feature for the former and for the latter, respectively. Responding to the target required an easy discrimination (Experiment 1) or a difficult one (Experiment 2). Repeating the target’s irrelevant color speeded search, but repeating its irrelevant shape did not. However, the irrelevant feature–response binding effect was similar for the two search dimensions. These findings invalidate the no-encoding account. Additional findings indicate that irrelevantfeature priming shares the main characteristics of other intertrial priming phenomena.