— Motivated Cognition Lab


Hickey, Acunzo, & Dell (in press). Suppressive Control of Incentive Salience in Real-World Human Vision. The Journal of Neuroscience. <link>

Reward-related activity in the dopaminergic midbrain is thought to guide animal behaviour, in part by boosting the perceptual and attentional processing of reward-predictive environmental stimuli. In line with this incentive salience hypothesis, studies of human visual search have shown that simple synthetic stimuli – like lines, shapes, or Gabor patches – capture attention to their location when they are characterized by reward-associated visual features like colour. In the real world, however, we commonly search for members of a category of visually-heterogenous objects – like people, cars, or trees – where category examples do not share low-level features. Is attention captured to examples of a reward-associated real-world object category? Here, we have human participants search for targets in photographs of city- and landscapes that contain task-irrelevant examples of a reward-associated category. We use the temporal precision of EEG machine learning and ERPs to show that these distractors acquire incentive salience and draw attention, but do not capture it. Instead, we find evidence of rapid, stimulus-triggered attentional suppression, such that the neural encoding of these objects is degraded relative to neutral objects. Humans appear able to suppress the incentive salience of reward-associated objects when they know these objects will be irrelevant, supporting the rapid deployment of attention to other objects that might be more useful. Incentive salience is thought to underlie key behaviours in eating disorders and addiction, among other conditions, and the kind of suppression identified here likely plays a role in mediating the attentional biases that emerge in these circumstances.

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Oscar Ferrante’s very cool work on statistical learning of distractor suppression is to appear in JoN. Congrats Oscar!

Ferrante, O., Zhigalov, A., Hickey, C., & Jensen, O. (in press). Statistical Learning of Distractor Suppression Down-Regulates Pre-Stimulus Neural Excitability in Early Visual Cortex. The Journal of Neuroscience.

A preprint is available here.

Visual attention is highly influenced by past experiences. Recent behavioral research has shown that expectations about the spatial location of distractors within a search array are implicitly learned, with expected distractors becoming less interfering. Little is known about the neural mechanism supporting this form of statistical learning. Here we used magnetoencephalography (MEG) to measure human brain activity to test whether proactive mechanisms are involved in the statistical learning of distractor locations. Specifically, we used a new technique called rapid invisible frequency tagging (RIFT) to assess neural excitability in early visual cortex during statistical learning of distractor suppression, while concurrently investigating the modulation of posterior alpha-band activity (8-12 Hz). Male and female human participants performed a visual search task in which a target was occasionally presented alongside a color-singleton distractor. Unbeknown to the participants, the distracting stimuli were presented with different probabilities across the two hemifields. RIFT analysis showed that early visual cortex exhibited reduced neural excitability in the pre-stimulus interval at retinotopic locations associated with higher distractor probabilities. In contrast, we did not find any evidence of expectation-driven distractor suppression in alpha-band activity. These findings indicate that proactive mechanisms of attention are involved in predictive distractor suppression and that these mechanisms are associated with altered neural excitability in early visual cortex. Moreover, our findings indicate that RIFT and alpha-band activity might subtend different and possibly independent attentional mechanisms.

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Many firsts in this paper!

  • Our first paper from data collected online.
  • Our first in collaboration with Devin Terhune at King’s College London.
  • Our first paper with a medical student – Ankita Sharma – completing the 1-year iBSc Human Neuroscience.
  • Ankita’s first publication!

Acunzo, Terhune, Sharma, & Hickey (in press). Absorption and dissociation mediate the relationship between direct verbal suggestibility and impulsivity/compulsivity. Acta Psychologica.

Direct verbal suggestibility refers to the capacity for an individual to experience perceptual, motor, affective and cognitive changes in response to verbal suggestions. Suggestibility is characterized by pronounced, yet reliable, inter-individual differences. Previous research and theoretical considerations suggest that greater impulsivity and compulsivity is associated to higher suggestibility, but the characteristics and mediating factors of this association are poorly understood. Using established psychometric measures in an online sample, we found positive correlations between the domain comprising impulsivity, compulsivity and behavioural activation/inhibition, and the domain of suggestibility, dissociation and absorption. We also observed that dissociation and absorption mediated the link between suggestibility and impulsivity, and between suggestibility and behavioural activation, respectively. These results confirm the positive link between suggestibility and the impulsivity/compulsivity domain and shed new light on the characterisation of traits associated with suggestibility.

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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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