A shared feature between the salient distractor and target turns early quitting effect to delayed quitting effect when the target is absent

In a seminal paper, Moher (Psychol Sci 31(1):31-42, 10.1177/0956797619886809, 2020) reported that a salient distractor induced observers to quit the search early when the target was absent and increased the error rate when the target was present. This early quitting effect (EQE) was considered to impact real-world target detection. We were interested in how the EQE would be influenced when the similarity between the target and the salient distractor increased. This may more closely resemble real-world situations and may reveal underlying mechanisms of the EQE, as increased similarity could either raise costs of attention suppression, leading to the disappearance or even reversal of the EQE, or trigger the sense of effort in searching, resulting in the appearance of the EQE. Through two experiments, we demonstrate that the effect of a salient distractor on detecting a target was limited by the similarity of the target and the salient distractor. In Experiment 1, we conducted a task with a salient distractor that differed in color, size, and orientation from the target to replicate the EQE. We found that participants reacted faster in target-absent trials and less accurately in target-present trials, thus validating the experiment. However, when the similarity of the salient distractor and target was increased by sharing the same orientation feature in Experiment 2, the EQE did not occur. Specifically, regardless of target presence, a salient distractor delayed the search time and did not influence the error rate. These findings support that attention suppression, rather than the sense of search effort, is a subprocess of the EQE.