Cortical Mechanisms of Prioritizing Selection for Rejection in Visual Search

Abstract

In visual search, the more one knows about a target, the faster one can find it. Surprisingly, target identification is also faster with knowledge about distractor-features. The latter is paradoxical, as it implies that to avoid the selection of an item, the item must somehow be selected to some degree. This conundrum has been termed the "ignoring paradox", and, to date, little is known about how the brain resolves it. Here, in data from four experiments using neuromagnetic brain recordings in male and female humans, we provide evidence that this paradox is resolved by giving distracting information priority in cortical processing. This attentional priority to distractors manifests as an enhanced early neuromagnetic index, which occurs before target-related processing, and regardless of distractor predictability. It is most pronounced on trials for which a response rapidly occurred, and is followed by a suppression of the distracting information. These observations together suggest that in visual search items cannot be ignored without first being selected. How can we ignore distracting stimuli in our environment? To do this successfully, a logical hypothesis is that as few neural resources as possible should be devoted to distractor processing. Yet, to avoid devoting resources to a distractor, the brain must somehow mark what to avoid; this is a philosophical problem, which has been termed the "ignoring paradox" or "white bear phenomenon". Here, we use MEG recordings to determine how the human brain resolves this paradox. Our data show that distractors are not only processed, they are given temporal priority, with the brain building a robust representation of the to-be-ignored items. Thus, successful suppression of distractors can only be achieved if distractors are first strongly neurally represented.

Gaze dynamics of feature-based distractor inhibition under the prior-knowledge and expectation

“…This interference occurred throughout the coherent moving stage, suggesting that sustained inhibition of the distractor direction could benefit the speed change detection in the target direction. Indeed, it has been suggested that distractors cannot be ignored before being selected in visual search (Donohue, Bartsch, Heinze, Schoenfeld, & Hopf, 2018). The decoding results in the distractor cueing condition demonstrated that monitoring the distractor direction while attending to the target direction serves as a means to reduce the between-direction interference.…”

Inhibition in selective attention

“…[101][102][103] It is selectively elicited by distractors, and is independent from other lateralized components reflective of attentional selection, such as the N2pc 76,93,100,104 and N1pc. 104 Accordingly, the Pd has been proposed to reflect a mechanism that prevents or terminates the allocation of attention toward a salient distractor. 10,105 Although in many cases the Pd follows the N2pc 76,102,[106][107][108] or N1pc 104 in the ERP waveform as predicted by the ignoring paradox, growing evidence indicates that salient distractors can also be inhibited (as evidenced by a Pd) in the absence of any neural evidence for attentional selection (e.g., the absence of an N2pc).…”

Inhibition in selective attention

“…The Pd, a transient positivity contralateral to the distractor, is especially relevant as its amplitude inversely scales with behavioral measures of distractor interference (102)(103)(104). It is selectively elicited by distractors, and is independent from other lateralized components reflective of attentional selection, such as the N2pc (76, 94,101,105) and N1pc (105). Accordingly, the Pd has been proposed to reflect a mechanism that prevents or terminates the allocation of attention towards a salient distractor (10,106).…”

“…Although in many cases the Pd follows the N2pc (76, 103, 107-109) or N1pc (105) in the ERP waveform as predicted by the ignoring paradox, growing evidence indicates that salient distractors can also be inhibited (as evidenced by a Pd) in the absence of any neural evidence for attentional selection (e.g., the absence of an N2pc) (10). Notably, in the majority of these studies, the experimental design allowed for statistical learning, either because the target and distractor identities were fixed (i.e., same color/shape) across trials (95,102,110,111), or because there was a high probability distractor location (86).…”