The Attentional Template Theory of Multiple-target Search Errors

Subsequent search miss (SSM) errors (also known as Satisfaction of Search)— worse target detection after finding a first target, is a common multiple-target search error. To explain SSMs, the Attentional Template theory predicts that a detected first target is utilized as an attentional template for subsequent targets, making observers more likely to miss dissimilar targets compared to similar targets in the same image. Across three behavioral and one EEG study, we tested the predictions of the Attentional Template theory by: 1) investigating how second target accuracy is affected by perceptual similarity between targets, 2) determining how long target similarity effects last, and 3) how the P300 is affected when the similarity between a first and second target is reduced. Observers were asked to search for up to two T and/or L-shaped targets that could differ in shape and rotation. Observers missed more second targets when they were dissimilar (e.g., a different shape and rotation), and this effect was expressed at shorter search durations (i.e., 1 second or less). For the P300, 1) observers had a larger P300 when targets were similar compared to dissimilar and when observers found one target (regardless of number or targets present), 2) a smaller P300 when targets were dissimilar compared to when targets were similar or observers found one target and 3) no difference in the P300 when only one target was found (regardless of similarity or whether one or two targets were present). Together, these findings broadly support the predictions of the Attentional Template theory and suggest that: 1) a first target, acting as an attentional template, can underlie SSMs, 2) when SSMs occur, attentional target recognition, as measured by the P300, is not allocated to second target processing, and 3) when targets are dissimilar, less attentional target recognition of second targets occurs.