| Popis: |
Theories of attention hypothesize the existence of an “attentional template” that contains target features in working or long-term memory. It is often assumed that the template contents are veridical, but recent studies have found that this is not true when the distractor set is linearly separable from the target (e.g., all distractors are “yellower” than an orange colored target). In such cases, the target representation in memory shifts away from distractor features (Navalpakkam & Itti, 2007) and develop a sharper boundary with distractors (Geng, DiQuattro & Helm, 2017). These changes in the target template are presumed to increase the target-to-distractor psychological distinctiveness and lead to better attentional selection, but it remains unclear what characteristics of the distractor context produce shifting vs. sharpening. Here, we test the hypothesis that the template representation shifts whenever the distractor set (i.e., all of the distractors) is linearly separable from the target, but that asymmetrical sharpening only occurs when linearly separable distractors are highly target-similar. Our results were consistent, suggesting that template shifting and asymmetrical sharpening are two mechanisms that increase the representational distinctiveness of targets from expected distractors and improve visual search performance. |
