When do speed and accuracy agree or disagree? A binding explanation

Similar distractors speed up the response to a visual target stimulus, whereas dissimilar distractors delay responding (Eriksen & Eriksen, 1974). However, Santee & Egeth (1980) report that similar distractors impair target identification. Experiments by Keren & Boer (1985) demonstrate that similar distractors may improve target identification, if target position is known in advance. The mechanisms underlying this positional effect remain largely unspecified. We propose a binding mechanism that may provide a means to give a coherent explanation for the seemingly discrepant pattern of results. Binding the identity and the position of the target stimulus is a necessary condition for both, correct identification and fast responding. If the correct stimulus identity is bound to the wrong (distractor) position, performance is impaired in terms of speed and accuracy. In addition, binding stimulus properties requires focused attention. Thus, increasing the likelihood of attending to the position of a distractor will increase the negative effects of the distractor. We tested this prediction in four experiments. The similarity and the temporal relation between distractor and target, and the predictability of the target position were varied. Besides replicating the results described above, the experiments provide new evidence for our binding explanation.