— Motivated Cognition Lab

Reward-priming impacts visual working memory maintenance: Evidence from human electrophysiology

Infanti, Hickey, Menghi, & Turatto, 2017, Visual Cognition

Reward can benefit visual processing of reward-associated objects in a non-strategic way. Recent studies have suggested that such influence extends also to visual working memory (VWM) representations of reward-associated stimuli. However, it is not clear yet which mechanisms underlie the behavioural effects in VWM tasks: reward could directly impact our ability to maintain representations in VWM or it could influence memory indirectly via priming of attentional selection. To distinguish between these alternatives we measured event-related potential indices of selective attention – the N2pc – and VWM maintenance – the CDA (contralateral delay activity) – while participants completed a VWM task. Results show that reward outcome in one trial caused similarly coloured targets to be strongly represented in VWM in subsequent trials, as expressed in a larger amplitude CDA. This was not preceded by a corresponding effect on attentional selection, in so far as our key manipulation had no impact on the N2pc. In a second experiment, we found that reward priming produced a behavioural benefit that emerged over time, suggesting the representations of reward-associated items stored in VWM are more resistant to interference and decay. We conclude that when the task stresses VWM maintenance, it is at this representational level that reward will have impact.

A paper based on work completed during Daniel’s very productive short sabbatical in Rovereto!

Motivation and short-term memory in visual search: Attention’s accelerator revisited.

Schneider, Bonmassar, & Hickey (2017, Cortex)

A cue indicating the possibility of cash reward will cause participants to perform memory-based visual search more efficiently. Thus if participants know there is money to be earned, they will be fast and accurate in finding a remembered object in a search display. A recent study has suggested that this performance benefit might reflect the use of multiple memory systems: when needed, participants can maintain the to-be-remembered object in both long-term and short-term visual memory and this redundancy benefits identification during search (Reinhart, McClenahan & Woodman, Psychological Science 2016, 27(6), 790-798). Here we test this compelling hypothesis. We had participants complete a memory-based visual search task involving a reward cue that either preceded presentation of the to-be-remembered target (pre-cue) or followed it (retro-cue). We tracked memory representation using two components of the ERP: contralateral delay activity (CDA), reflecting short-term visual memory, and the anterior P170, reflecting long-term storage. Results show that only the pre-cue impacted our ERP indices of memory. However, both types of cue elicited frontal ERP activity tied to reward processing, and both had equivalent impact on visual search behavior and associated ERP components. Reward prospect thus has an impact on memory-guided visual search, but this does not appear to be necessarily mediated by a change in visual memory representations. Our results demonstrate that the impact of reward prospect on search is not a simple product of improved memory for target templates.

On June 16th, 2017, a mini-workshop on ‘Motivation, selection, and information-seeking’ will take place at the Center for Mind / Brain Science (CIMEC) of the University of Trento, Italy.

Confirmed speakers are:

Leonardo Chelazzi (University of Verona, IT)
Giorgio Coricelli (University of Trento, IT; University of Southern California, USA)
Jackie Gottlieb (Columbia University, USA)
Clayton Hickey (University of Trento, IT)
Jane Raymond (Birmingham University, UK)

Each speaker will give a 40 minute talk to be followed by a 20 minute question period.

The workshop will be held in the Aula Magna of Palazzo Piomarta, which is located at Corso Bettini 84, Rovereto, Italy. Talks will begin at 11 am and finish by 6pm. (Note that the workshop is preceded by a 10am colloquium at the same location by Gregor Thut of the University of Glasgow).

All are welcome, there is no fee, and no formal registration is required. Drop me a quick note if you plan on coming (clayton.hickey@unitn.it).

Hope you can join us!

clayton

Reward selectively modulates the lingering neural representation of recently attended objects in natural scenes.

Hickey & Peelen

Theories of reinforcement learning and approach behaviour suggest that reward can increase the perceptual salience of environmental stimuli, ensuring that potential predictors of outcome are noticed in the future. But outcome commonly follows visual processing of the environment, occurring even when potential reward cues have long disappeared. How can reward feedback retroactively cause now-absent stimuli to become attention-drawing in the future? One possibility is that reward and attention interact to prime lingering visual representations of attended stimuli that sustain through the interval separating stimulus and outcome. Here we test this idea using multivariate pattern analysis of fMRI data collected from male and female humans. While in the scanner, participants searched for examples of target categories in briefly-presented pictures of city- and landscapes. Correct task performance was followed by reward feedback that could randomly have either high or low magnitude. Analysis showed that high-magnitude reward feedback boosted the lingering representation of target categories while reducing the representation of nontarget categories. The magnitude of this effect in each participant predicted the behavioural impact of reward on search performance in subsequent trials. Other analyses show that sensitivity to reward – as expressed in a personality questionnaire and in reactivity to reward feedback in the dopaminergic midbrain – predicted reward-elicited variance in lingering target and nontarget representations. Credit for rewarding outcome thus appears to be assigned to the target representation, causing the visual system to become sensitized for similar objects in the future.

Jacqueline Gottlieb, of Columbia University NY, is visiting the Center for Mind / Brain Science at the University of Trento on a 10-week sabbatical.

Jackie will be speaking in a colloquium talk at 2pm on May 12th, 2017 (Fedrigotti 3rd floor conference room). All are welcome!

Session ‘Attention: Features’

Saturday, May 20th, 3pm, Talk Room 1

Ludwig Barbaro successfully defended his PhD dissertation on March 8th. He adds this degree to his existing medical diploma, so congratulations Dr. Dr. Barbaro!

Applications invited for the CIMEC Masters program. Here are a poster and brochure providing details.

Weaver, Hickey, & van Zoest (2017). The impact of salience and visual working memory on the monitoring and control of saccadic behavior: An eye-tracking and EEG study. 

In a concurrent eye-tracking and EEG study, we investigated the impact of salience on the monitoring and control of eye movement behavior and the role of visual working memory (VWM) capacity in mediating this effect. Participants made eye movements to a unique line-segment target embedded in a search display also containing a unique distractor. Target and distractor salience was manipulated by varying degree of orientation offset from a homogenous background. VWM capacity was measured using a change-detection task. Results showed greater likelihood of incorrect saccades when the distractor was relatively more salient than when the target was salient. Misdirected saccades to salient distractors were strongly represented in the error-monitoring system by rapid and robust error- related negativity (ERN), which predicted a significant adjustment of oculomotor behavior. Misdirected saccades to less-salient distractors, while arguably representing larger errors, were not as well detected or utilized by the error/ performance-monitoring system. This system was instead better engaged in tasks requiring greater cognitive control and by individuals with higher VWM capacity. Our findings show that relative salience of task-relevant and task- irrelevant stimuli can define situations where an increase in cognitive control is necessary, with individual differences in VWM capacity explaining significant variance in the degree of monitoring and control of goal-directed eye movement behavior. The present study supports a conflict-monitoring interpretation of the ERN, whereby the level of competition between different responses, and the stimuli that define these responses, was more important in the generation of an enhanced ERN than the error commission itself.

Weaver, van Zoest, & Hickey (in press). A temporal dependency account of attentional inhibition in oculomotor control. Neuroimage. <link>

We used concurrent electroencephalogram (EEG) and eye tracking to investigate the role of covert attentional mechanisms in the control of oculomotor behavior. Human participants made speeded saccades to targets that were presented alongside salient distractors. By subsequently sorting trials based on whether the distractor was strongly represented or suppressed by the visual system – as evident in the accuracy (Exp. 1) or quality of the saccade (Exp. 2) – we could characterize and contrast pre-saccadic neural activity as a function of whether oculomotor control was established. Results show that saccadic behavior is strongly linked to the operation of attentional mechanisms in visual cortex. In Experiment 1, accurate saccades were preceded by attentional selection of the target – indexed by a target-elicited N2pc component – and by attentional suppression of the distractor – indexed by early and late distractor-elicited distractor positivity (Pd) components. In Experiment 2, the strength of distractor suppression predicted the degree to which the path of slower saccades would deviate away from the distractor en route to the target. However, results also demonstrated clear dissociations of covert and overt selective control, with saccadic latency in particular showing no relationship to the latency of covert selective mechanisms. Eye movements could thus be initiated prior to the onset of attentional ERP components, resulting in stimulus-driven behaviour. Taken together, the results indicate that attentional mechanisms play a role in determining saccadic behavior, but that saccade timing is not contingent on the deployment of attention. This creates a temporal dependency, whereby attention fosters oculomotor control only when attentional mechanisms are given sufficient opportunity to impact stimuli representations before an eye movement is executed.