Abstract
When targets frequently co-occur with highly similar distractors, attentional sharpening is observed wherein target feature representations are narrowed to aid target-distractor discriminations. This sharpening might be due to local tuning mechanisms through increased activation of target values along with suppression of learned distractor values (i.e., sharpening limited to learned features). Conversely, adjustments in global control settings may aid in conflict resolution more generally (i.e., sharpening is transferable to unlearned features). To contrast these models, we asked participants to locate and respond to color targets that co-occurred with two colored distractors (either from an intermediate distance +/-60º or near distance +/-30º from the target in hue space). Additionally, participants were assigned to either Mostly Intermediate or Mostly Near groups where the proportion of intermediate displays to near displays was 80:20 or 20:80, respectively, during a training phase. Following training, the ratio of intermediate to near displays was set to 50:50. In this transfer phase, the target and distractor colors either remained the same (Experiment 1) or changed (Experiment 2). In line with attentional sharpening, during the training phase distractors near the target color in hue space were less interfering for the Mostly Near group than for the Mostly Intermediate group. Critically, this attentional sharpening persisted in the transfer phase only when the target color remained constant. Thus, because the transfer of attentional sharpening was limited to trained features, our results indicate that this process occurs through local tuning processes rather than through broader attentional control mechanisms.