Abstract
Stress interferes with instrumental learning. However, choice is also influenced by non-instrumental factors, most strikingly by biases arising from Pavlovian associations that facilitate action in pursuit of rewards and inaction in the face of punishment. Whether stress impacts on instrumental learning via these Pavlovian associations is unknown. Here, in a task where valence (reward or punishment) and action (go or no-go) were orthogonalised, we asked whether the impact of stress on learning was action or valence specific. We exposed 60 human participants either to stress (socially-evaluated cold pressor test) or a control condition (room temperature water). We contrasted two hypotheses: that stress would lead to a non-selective increase in the expression of Pavlovian biases; or that stress, as an aversive state, might specifically impact action production due to the Pavlovian linkage between inaction and aversive states. We found support for the second of these hypotheses. Stress specifically impaired learning to produce an action, irrespective of the valence of the outcome, an effect consistent with a Pavlovian linkage between punishment and inaction. This deficit in action-learning was also reflected in pupillary responses; stressed individuals showed attenuated pupillary responses to action, hinting at a noradrenergic contribution to impaired action-learning under stress.
Highlights
Following a recent study which found no effect of stress upon model-based learning but did observe a relationship with cortisol concentration changes[5] we looked for a correlation between model parameters and cortisol change[29]
Stress might induce a greater dependence upon Pavlovian biases, in line with the idea of a stress-induced general shift from computationally demanding flexible systems towards more automatic forms of control[2,3,4,5,6]
We found evidence supporting this second hypothesis; stressed participants were impaired in responding to both Go cues, and showing no deficit for both NoGo cues (Fig. 3), a conclusion supported by reinforcement learning models (Fig. 4)
Summary
Given the linkage between negative valence and inaction[11], this suggests an alternative hypothesis, namely that stress impacts on instrumental learning via the Pavlovian coupling of punishment and inaction Such a coupling would explain the augmented inhibition of pre-potent actions observed under threat of shock[19], and predicts that sustained activation of punishment-related tendencies (such as active avoidance, or inaction11) might interfere with the learning of instrumental responses which required different behavioural outputs (such as approach). To distinguish between these two competing hypotheses we compared a Stressed group who underwent the socially-evaluated Cold Pressor Test (CPT), and a Control group who submerged their hands in room-temperature water[5,6,7] (Fig. 1A).
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
