— Motivated Cognition Lab

October, 2018 Monthly archive

Different effects of spatial and temporal attention on the integration and segregation of stimuli in time

Poppy Sharp, David Melcher, and Clayton Hickey

in press, Attention, Perception and Psychophysics


Having expectations about when and where relevant stimuli will appear engenders endogenous temporal and spatial orienting, and can provide vital benefits to visual processing. Whilst more is known about how each of these forms of orienting affect spatial processing, comparatively little is understood about their influence on temporal integration and segregation of rapid sequential stimuli. A critical question is whether the influence of spatial cueing on temporal processing involves independent spatial and temporal orienting effects or a synergistic spatiotemporal impact. Here, we delineate between temporal and spatial orienting engendered by endogenous cues by using a paradigm with identical visual stimulation when the goal is to integrate or segregate stimuli in separate blocks of trials. We find strong effects of spatial orienting on both integration and segregation performance. In contrast, temporal orienting engendered only an invalid cueing cost, for integration trials only. This clear differentiation between spatial and temporal cueing effects provides constraints to inform arbitration between theories of how attention biases the visual processing stream and influences the organization of visual perception in time.

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From a fruitful ongoing collaboration with Daniel Schneider and Edmund Wascher in Dortmund.

Working memory contents can be prioritized by retroactively deploying attention within memory. This is broadly interpreted as evidence of a concentration of memory resources to the attended, to-be-remembered stimulus. However, online attentional selection is known to additionally depend on distractor inhibition, raising the viable alternative that attentional deployment in working memory involves inhibitory control processes. Here, we demonstrate that active inhibition plays a central role in the deployment of attention in working memory. We do so using a retroactive cueing paradigm, where a briefly presented memory array is followed by a cue indicating a to-be-remembered target (Experiment 1) or a to-be-forgotten distractor (Experiment 2). We identify discrete indices of target selection and distractor inhibition in lateralized oscillatory activity over visual areas. When a retroactive cue identifies the location of a target, results show rapid decrease of lateral, target-elicited alpha band activity, representing attentional orienting toward the target. This is followed only later by emergence of an increase in distractor-elicited alpha activity, reflecting distractor inhibition. In contrast, when the retroactive cue identifies a distractor, evidence of distractor inhibition emerges first, only later followed by target selection. These results thus demonstrate that separate excitatory and inhibitory processes underlie the deployment of attention on the level of working memory representations.

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