— Motivated Cognition Lab

A big project from Poppy Sharp’s PhD thesis has (finally) been published! Congrats Poppy!

Sharp, Gutteling, Melcher, & Hickey (in press). Spatial attention tunes temporal processing in early visual cortex by speeding and slowing alpha oscillations. The Journal of Neuroscience.

The perception of dynamic visual stimuli relies on two apparently conflicting perceptual mechanisms: rapid visual input must sometimes be integrated into unitary percepts but at other times must be segregated or parsed into separate objects or events. Though they have opposite effects on our perceptual experience, the deployment of spatial attention benefits both of these operations. Little is known about the neural mechanisms underlying this impact of spatial attention on temporal perception. Here we use magnetoencephalography (MEG) to demonstrate that the deployment of spatial attention for the purpose of segregating or integrating visual stimuli impacts pre-stimulus oscillatory activity in retinotopic visual brain areas where the attended location is represented. Alpha-band oscillations contralateral to an attended location are therefore faster than ipsilateral oscillations when stimuli appearing at this location will need to be segregated, but slower in expectation of the need for integration, consistent with the idea that alpha frequency is linked to perceptual sampling rate. These results demonstrate a novel interaction between temporal visual processing and the allocation of attention in space.

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First collaboration with Anna Shubö’s group in Marburg, hopefully more to follow!

Abbasi, H., Kadel, A., Hickey, C. & Schubö, A. (in press). Combined influences of strategy and selection history on attentional control. Psychophysiology.

Combined Influences of Strategy and Selection History on Attentional Control

Visual attention is guided by top-down mechanisms and pre-stimulus task preparation, but also by selection history (i.e., the bias to prioritize previously attended items). Here we examine how these influences combine. Two groups of participants completed two intermingled tasks. One task involved categorization of a unique target; one group categorized the target based on color, and the other based on shape. The other task involved searching for a target defined by unique shape while ignoring a distractor defined by unique color. Our expectation was that the search task would be difficult for the color categorization group because their categorization task required attentional resolution of color, but the search task required that they ignore color. In some experimental blocks, trials from the two tasks appeared predictably, giving the color categorization group an opportunity to strategically prepare by switching between color-prioritizing and shape-prioritizing attentional templates. We looked to pre-stimulus oscillatory activity as a direct index of this preparation, and to reaction times and post-stimulus ERPs for markers of resultant change in attentional deployment. Results showed that preparation in the color-categorization group sharpened attentional templates, such that these participants became less sensitive to the color distractor in the search task. But preparation was not sufficient to entirely negate the influence of selection history, and participants in the color-categorization group continued to show a propensity to attend to the color distractor. These results indicate that preparatory effort can be scaled to the anticipated attentional requirements, but attention is nevertheless considerably biased by selection history.

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van Zoest, Huber, Weaver, & Hickey (in press). Strategic distractor suppression improves selective control in human vision. The Journal of Neuroscience. <link>

– Behavioural, ERP, and oscillatory data from 3 EEG/eye-tracking experiments shows that people can prepare to ignore distractors based on foreknowledge of distractor location or color.
– When a cue identifies the location of an upcoming distractor, lateral alpha over posterior cortex predicts N2pc/Pd amplitude. When cue-elicited alpha is big, distractor-elicted N2pc is small.

Our visual environment is complicated and our cognitive capacity is limited. As a result, we must strategically ignore some stimuli in order to prioritize others. Common-sense suggests that foreknowledge of distractor characteristics, like location or color, might help us ignore these objects. But empirical studies have provided mixed evidence, often showing that knowing about a distractor before it appears counter-intuitively leads to its attentional selection. What has looked like strategic distractor suppression in the past is now commonly explained as a product of prior experience and implicit statistical learning, and the long-standing notion that distractor suppression is reflected in alpha-band oscillatory brain activity has been challenged by results appearing to link alpha to target resolution. Can we strategically, proactively suppress distractors? And, if so, does this involve alpha? Here, we use concurrent recording of human EEG and eye movements in optimized experimental designs to identify behaviour and brain activity associated with proactive distractor suppression. Results from 3 experiments show that knowing about distractors before they appear causes a reduction in electrophysiological indices of covert attentional selection of these objects and a reduction in the overt deployment of the eyes to their location. This control is established before the distractor appears and is predicted by the power of cue-elicited alpha activity over visual cortex. Foreknowledge of distractor characteristics therefore leads to improved selective control, and alpha oscillations in visual cortex reflect the implementation of this strategic, proactive mechanism.

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They say, 'The fox knows many things, but the hedgehog knows one great th…"  - New Yorker Cartoon' Premium Giclee Print - Charles Barsotti | Art.com

Clayton and Wieske have published a short commentary on a recent review from Luck, Gaspelin, Folk, Remington, & Theeuwes (2020, Visual Cognition).

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Experiments from Daniele’s masters and Giacomo’s internship will appear in a paper in the Journal of Cognitive Neuroscience!

Here’s a preprint.

Ultrafast object detection in naturalistic vision relies on ultrafast distractor suppression.

Hickey, Pollicino, Bertazzoli, and Barbaro

People are quicker to detect examples of real-world object categories in natural scenes than is predicted by classic attention theories. One explanation for this puzzle suggests that experience renders the visual system sensitive to mid-level features diagnosing target presence. These are detected without the need for spatial attention, much as occurs for targets defined by low-level features like color or orientation. The alternative is that naturalistic search relies on spatial attention but is highly efficient because global scene information can be used to quickly reject non-target objects and locations. Here, we use ERPs to differentiate between these possibilities. Results show that hallmark evidence of ultrafast target detection in frontal brain activity is preceded by an index of spatially-specific distractor suppression in visual cortex. Naturalistic search for heterogenous targets therefore appears to rely on spatial operations that act on neural object representations, as predicted by classic attention theory. Participants appear able to rapidly reject non-target objects and locations in order to constrain naturalistic search and increase search efficiency, possibly reflecting the use of global scene information.

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Clayton has moved to the brand-new Center for Human Brain Health. His office is on the ground floor, room G04.

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Poppy successfully defended her PhD at the CIMEC in Rovereto, Italy, on April 5th, 2019.

Poppy’s work examines the role of spatial attention on temporal processing of visual stimuli. Two papers are available here on the website and another is in preparation.

Poppy clearly impressed her committee, resulting in a prestigious cum laude notation to her PhD!

Poppy’s dissertation work was co-supervised by Clayton Hickey and David Melcher, and we look suitably proud in the attached photo.

Congratulations Poppy!

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Jackie Dell has won a prestigious Fulbright award! This will support her PhD research on addiction and incentive salience at the University of Birmingham.

Jackie is finishing her Masters at the University of South Florida with Jennifer O’Brien and will begin at the University of Birmingham in the fall of 2019.

Congratulations Jackie!

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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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