Pupil dilation reflects effortful action invigoration in overcoming aversive Pavlovian biases

“Pavlovian” or “motivational” biases describe the phenomenon that the valence of prospective outcomes modulates action invigoration: Reward prospect invigorates action, whereas punishment prospect suppresses it. The adaptive role of these biases in decision-making is still unclear. One idea is that they constitute a fast-and-frugal decision strategy in situations characterized by high arousal, e.g., in presence of a predator, which demand a quick response. In this pre-registered study (N = 35), we tested whether such a situation—induced via subliminally presented angry versus neutral faces—leads to increased reliance on Pavlovian biases. We measured trial-by-trial arousal by tracking pupil diameter while participants performed an orthogonalized Motivational Go/NoGo Task. Pavlovian biases were present in responses, reaction times, and even gaze, with lower gaze dispersion under aversive cues reflecting “freezing of gaze.” The subliminally presented faces did not affect responses, reaction times, or pupil diameter, suggesting that the arousal manipulation was ineffective. However, pupil dilations reflected facets of bias suppression, specifically the physical (but not cognitive) effort needed to overcome aversive inhibition: Particularly strong and sustained dilations occurred when participants managed to perform Go responses to aversive cues. Conversely, no such dilations occurred when they managed to inhibit responses to Win cues. These results suggest that pupil diameter does not reflect response conflict per se nor the inhibition of prepotent responses, but specifically effortful action invigoration as needed to overcome aversive inhibition. We discuss our results in the context of the “value of work” theory of striatal dopamine

Neurometric Intertemporal Choice EEG Study

Lin, H., Saunders, B., Hutcherson, C. A., & Inzlicht, M. (2018). Midfrontal theta and pupil dilation parametrically track subjective conflict (but also surprise) during intertemporal choice. NeuroImage, 172, 838-852. doi:10.1016/j.neuroimage.2017.10.05

Expectations of reward and efficacy guide cognitive control allocation

The amount of mental effort we invest in a task is influenced by the reward we can expect if we perform that task well. However, some of the rewards that have the greatest potential for driving these efforts are partly determined by factors beyond ones control. In such cases, effort has more limited efficacy for obtaining rewards. According to the Expected Value of Control theory, people integrate information about the expected reward and efficacy of task performance to determine the expected value of control, and then adjust their control allocation (i.e., mental effort) accordingly. Here we test this theorys key behavioral and neural predictions. We show that participants invest more cognitive control when this control is more rewarding and more efficacious, and that these incentive components separately modulate EEG signatures of incentive evaluation and proactive control allocation. Our findings support the prediction that people combine expectations of reward and efficacy to determine how much effort to invest

Pupillary Response in an Auditory Rhythm Omissions Task in Parkinson´s Disease: A Pilot Study

When presented with short, rhythmical, musical excerpts, containing omitted beats which vary in saliency in terms of rhythmical patterns (contextual omission), and position (salience omissions), fMRI studies have shown a small effect depending on position of omission. Furthermore, when presented with auditory stimuli, a pupillary dilation response (PDR) is evoked, resulting in a pupillary peak dilation (PPD) sometime after stimulus onset. By utilizing and adapting an auditory beat-omission fMRI paradigm, to allow measurement of PDR and PPD, we used pupillometry data to investigate the effect of contextual omission (Simple vs Complex rhythm) and salience omission (O1 vs O2). We report data from a total of 25 participants, based on 45 datasets. The data were analyzed using four separate direct t-tests. We found that the omission has an effect on PPD, in that the most metrical salient omission (O1) results in a higher activation level compared to a less salient omission (O2), i.e., PPD was significantly higher in O1 simple rhythm omissions, and in O1 complex rhythm omissions, at an uncorrected threshold level.Masteroppgave i psykologiMAPSYK360INTL-HFINTL-PSYKINTL-SVINTL-MNINTL-MEDINTL-KMDMAPS-PSYKINTL-JU

Powerful men on top: Stereotypes interact with metaphors in social categorizations

We examined whether people can simultaneously apply 2 cognitive strategies in social categorizations. Specifically, we tested whether stereotypes concerning social power of gender categories interact with metaphoric power-space links. Based on the conceptual blending perspective suggesting that semantically consistent concepts acquire each other's properties, we predicted the following: Given that stereotypes create expectations linking gender with power, and metaphorically power is linked with vertical space, the conceptual blend of gender-power-space would invoke representations of male targets at the top vertical position when categorizing them as powerful, while female targets at the bottom when categorizing them as powerless. Across 6 studies, we show that the concept of gender is simulated spatially when people attribute power to male, but not female, targets. The predicted power-gender blending involved simulations of men judged as powerful when presented in upper location as opposed to women judged as powerful in upper location and men judged as powerful in lower location. Our hypothesis was further corroborated using pupillometry to assess preconscious processing, whereby stereotypically inconsistent orientations of gender and power evoked pupillary markers indicative of surprise. Our studies suggest that gender-power stereotypic expectations interact with the power-space metaphor in social categorization

Midfrontal theta and pupil dilation parametrically track subjective conflict (but also surprise) during intertemporal choice

Many everyday choices are based on personal, subjective preferences. When choosing between two options, we often feel conflicted, especially when trading off costs and benefits occurring at different times (e.g., saving for later versus spending now). Although previous work has investigated the neurophysiological basis of conflict during inhibitory control tasks, less is known about subjective conflict resulting from competing subjective preferences. In this pre-registered study, we investigated subjective conflict during intertemporal choice, whereby participants chose between smaller immediate versus larger delayed rewards (e.g., $15 today vs.$22 in 30 days). We used economic modeling to parametrically vary eleven different levels of conflict, and recorded EEG data and pupil dilation. Midfrontal theta power, derived from EEG, correlated with pupil responses, and our results suggest that these signals track different gradations of subjective conflict. Unexpectedly, both signals were also maximally enhanced when decisions were surprisingly easy. Therefore, these signals may track events requiring increased attention and adaptive shifts in behavioral responses, with subjective conflict being only one type of such event. Our results suggest that the neural systems underlying midfrontal theta and pupil responses interact when weighing costs and benefits during intertemporal choice. Thus, understanding these interactions might elucidate how individuals resolve self-control conflicts

On the computational and neural characterisation of reward learning behaviour

Do we learn differently from better- or worse-than-expected decision outcomes? Over the past decades, converging evidence emerged about the crucial role of the dopaminergic system in guiding learning through signalling reward prediction errors. However, a complete characterisation of how this learning process is influenced by feedback valence, surprise, and uncertainty is still lacking. The current thesis focuses on exploring the differential behavioural and neural mechanisms related to learning from positive versus negative decision outcomes whilst examining the influence of uncertainty on these processes. In our first experiment, we collected simultaneous EEG and eye-tracking data during a probabilistic reversal learning task. Using multivariate EEG analysis, we replicated the two distinct spatiotemporal reward learning systems reported by Fouragnan and colleagues (2015). Given that locus-coeruleus-noradrenaline (LC-NA) activity is difficult to directly measure non-invasively in humans, we used the pupil response as a proxy for LC-NA activity. We showed that the increased feedback-related pupil response to negative compared to positive outcomes is exclusively driven by increased negative feedback processing in the early and the late system. Additionally, a stronger coupling between early, but not late, system activity and the feedback-evoked pupil response was linked to reduced performance, increased uncertainty as well as exploration propensity. In line with existing research indicating the LC-NA network in uncertainty signalling and network resets, we propose that when internal estimates of environmental uncertainty surge in response to negative feedback, the early system, regulated by noradrenergic activity, interrupts processing in structures of the late system. Such network resets may aid flexible adaptation to changing environments by simultaneously reducing the influence of learned value representations and increasing the neural gain of new information. Our second experimental chapter extended the above study by examining post-feedback response adaptation as a function of early and late system activity. Specifically, we utilised hierarchical drift diffusion modelling, in which the drift rate and boundary separation were constrained by trial-wise and valence-specific early and late system activity. We hypothesised that an LC-NA-induced interruption in reward learning structures would reduce subsequent evidence accumulation as learned value representations become less influential and participants consider a reversal in reward contingencies more likely. Consistent with this hypothesis, we found that increased negative feedback processing by the early and late system reduced evidence accumulation in the next trial. Furthermore, a stronger association between the feedback-locked pupil response and early system activity following negative outcomes was significantly associated with the degree of drift rate reduction prompted by the early system. This result implies that LC-NA mediated network resets may be primarily associated with the early system, which in turn may down-regulate late system activity. Our final study explored differential value learning in the Balloon Analogue Risk Task (BART) under varying levels of uncertainty. By deriving differential learning rates from the newly developed Scaled Target Learning model, we showed that participants preferentially learn from positive compared to negative feedback under increased levels of uncertainty. Furthermore, the degree of this learning bias was negatively related to performance under the highest level of uncertainty. These results provide further evidence for differential mechanisms implicated in positive and negative feedback processing and indicate the important modulatory role of uncertainty in reward learning. Together, this thesis provides novel insights on the valence-specific neural and behavioural characteristics associated with feedback processing. Our results also highlight the important modulatory role uncertainty and noradrenaline play in reward learning and thus provide a more complete depiction of reward learning behaviour