Rapid development of inhibitory effects in response to novel features: It's mostly target-feature enhancement.

In some visual search scenarios, the presence of a singleton distractor leads to faster search performance. This has been coined as the inhibition effect and is believed to represent avoidance of the singleton distractor. Research has identified two contributing components: a bias towards target features, target-feature enhancement, a bias away from distractor features, distractor-feature suppression. The current study examines how each of these effects independently develops in response to novel stimuli. In short blocks participants completed a search for a pre-defined target shape. Each block the colour of the target and the distractor were randomized so that the initial and subsequent attentional adaptations to these features could be assessed (via eye-tracking). These mini-blocks reveal substantial information about the development of the inhibition effect. Incredibly, we observe the classic inhibition effect (shorter RTs on distractor-present trials) as soon as the second trial of each block. Furthermore, the effect emerged even if it was the first presentation of the distractor feature. Gaze analysis concurs with this, eyes avoided the distractor when the target feature was known, but the distractor feature unknown. This shows compelling evidence for guidance from target-feature enhancement. However, some evidence for distractor-feature suppression is observed, further oculomotor suppression of the distractor is seen after its initial presentation. Together, the current results show that the inhibition effect develops rapidly in visual search displays, and that while a large portion of the effect can be accounted for by target-enhancement, distractor-suppression may still have a role in influencing attentional allocations.