Comparing Segmentation by Time and by Motion in Visual Search: An fMRI Investigation

Brain activity was recorded while participants engaged in a difficult visual search task for a target defined by the spatial configuration of its component elements. The search displays were segmented by time (a preview then a search display), by motion, or were unsegmented. A preparatory network showed activity to the preview display, in the time but not in the motion segmentation condition. A region of the precuneus showed (i) higher activation when displays were segmented by time or by motion, and (ii) correlated activity with larger segmentation benefits behaviorally, regardless of the cue. Additionally, the results revealed that success in temporal segmentation was correlated with reduced activation in early visual areas, including V1. The results depict partially overlapping brain networks for segmentation in search by time and motion, with both cue-independent and cue-specific mechanisms.

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On the Temporal Relation of Top–Down and Bottom–Up Mechanisms during Guidance of Attention

Journal of Cognitive Neuroscience ◽

10.1162/jocn.2009.21222 ◽

2010 ◽

Vol 22 (4) ◽

pp. 640-654 ◽

Cited By ~ 22

Author(s):

Agnieszka Wykowska ◽

Anna Schubö

Keyword(s):

Visual Search ◽

Search Task ◽

Visual Search Task ◽

Target Item ◽

Search Display ◽

Error Rates ◽

Top Down ◽

Bottom Up ◽

Focal Attention ◽

Dynamic Interplay

Two mechanisms are said to be responsible for guiding focal attention in visual selection: bottom–up, saliency-driven capture and top–down control. These mechanisms were examined with a paradigm that combined a visual search task with postdisplay probe detection. Two SOAs between the search display and probe onsets were introduced to investigate how attention was allocated to particular items at different points in time. The dynamic interplay between bottom–up and top–down mechanisms was investigated with ERP methodology. ERPs locked to the search displays showed that top–down control needed time to develop. N2pc indicated allocation of attention to the target item and not to the irrelevant singleton. ERPs locked to probes revealed modulations in the P1 component reflecting top–down control of focal attention at the long SOA. Early bottom–up effects were observed in the error rates at the short SOA. Taken together, the present results show that the top–down mechanism takes time to guide focal attention to the relevant target item and that it is potent enough to limit bottom–up attentional capture.

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Attentional capture by signals of food and drink reward persists following outcome devaluation

10.31234/osf.io/2jmpb ◽

2021 ◽

Author(s):

Poppy Watson ◽

Yenti Pavri ◽

Jenny Thao Le ◽

Daniel Pearson ◽

Mike Le Pelley

Keyword(s):

Visual Search ◽

Attentional Capture ◽

Search Task ◽

Visual Search Task ◽

Search Display ◽

Negative Consequences ◽

Ad Libitum ◽

Food And Drink ◽

Attentional Mechanism ◽

Outcome Devaluation

Attention, the mechanism that prioritises stimuli in the environment for further processing, plays an important role in behavioural choice. In the current study we investigated the automatic orienting of attention to cues that signal reward. Such attentional capture occurs despite negative consequences, but the sensitivity of this counterproductive and reflexive behaviour to shifts in outcome value has not yet been investigated. Thirsty participants completed a visual-search task, in which the colour of a distractor stimulus in the search display signalled whether participants would earn water or potato chips for making a rapid eye movement to a diamond target, but looking at the coloured distractor was punished by omission of the signalled reward. Nevertheless, participants looked at the water-signalling distractor more frequently than the chips-signalling distractor. Half the participants then drank water ad libitum before continuing with the visual-search task. Although the water was now significantly less desirable for half of the participants, there was no difference between groups in the tendency for the water-signalling distractor to capture attention. These findings suggest that once established, attentional bias to signals of food and drink rewards persists, even when those outcomes are no longer valuable. This suggests a ‘habit-like’ attentional mechanism which prioritises reward stimuli in the environment for further action, regardless of whether those stimuli are aligned with current goals, or currently desired.

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