Flexible control of Pavlovian-instrumental transfer based on expected reward value.

Abstract

The Pavlovian-instrumental transfer (PIT) paradigm is widely used to assay the motivational influence of reward-predictive cues, reflected by their ability to invigorate instrumental behavior. Leading theories assume that a cue's motivational properties are tied to predicted reward value. We outline an alternative view that recognizes that reward-predictive cues may suppress rather than motivate instrumental behavior under certain conditions, an effect termed positive conditioned suppression. We posit that cues signaling imminent reward delivery tend to inhibit instrumental behavior, which is exploratory by nature, in order to facilitate efficient retrieval of the expected reward. According to this view, the motivation to engage in instrumental behavior during a cue should be inversely related to the value of the predicted reward, since there is more to lose by failing to secure a high-value reward than a low-value reward. We tested this hypothesis in rats using a PIT protocol known to induce positive conditioned suppression. In Experiment 1, cues signaling different reward magnitudes elicited distinct response patterns. Whereas the one-pellet cue increased instrumental behavior, cues signaling three or nine pellets suppressed instrumental behavior and elicited high levels of food-port activity. Experiment 2 found that reward-predictive cues suppressed instrumental behavior and increased food-port activity in a flexible manner that was disrupted by post-training reward devaluation. Further analyses suggest that these findings were not driven by overt competition between the instrumental and food-port responses. We discuss how the PIT task may provide a useful tool for studying cognitive control over cue-motivated behavior in rodents.

High stakes slow responding, but do not help overcome Pavlovian biases in humans

“…Another possible interpretation of our findings is that the response slowing under large stake magnitudes is an instance of positive conditioned suppression as previously reported in rodents (Azrin & Hake, 1969; Marshall, Halbout, Munson, Hutson, & Ostlund, 2023; Van Dyne, 1971). In positive conditioned suppression, cues signaling the immanent receipt of a reward suppress responding.…”

“…However, this suppression can extend backwards in time such that it even affects the instrumental response required to obtain the reward (i.e., a lever press). A recent study found small rewards to invigorate responding in line with classical PIT findings (Marshall et al, 2023). However, large rewards suppressed instrumental lever pressing and diminished PIT effects, suggestive of positive conditioned suppression interfering with PIT in a way similar of our findings.…”

“…However, this suppression can extend backwards in time such that it even affects the instrumental response required to obtain the reward (i.e., a lever press). A recent study found small rewards to invigorate responding in line with classical PIT findings (Marshall et al 2023).…”

“…It is thus possible that both (automatic) positive conditioned suppression and (voluntary) heightened cognitive control recruitment triggered by motivational conflict are present, or that positive conditioned suppression is (partially) a consequence of cognitive control recruitment. Future studies could test whether the slowing induced by high stakes is sensitive to the temporal delay between response execution and outcome delivery, which would argue for interference between reward collection and response selection as the cause of slowing (Delamater & Holland, 2008; Marshall et al, 2023; Marshall & Ostlund, 2018; Meltzer & Hamm, 1978; Miczek & Grossman, 1971).…”

“…This slowing down can be adaptive in high threat situations in which response postponement mimics nonresponding, similar to freezing itself (Bach, 2015), although in our data, the slowing did not affect participants’ eventual propensity to execute a Go response. This slowing might also be adaptive from the perspective of positive conditioned suppression in focusing an agent on reward collection and consumption rather than exploring other options in the meantime (Marshall et al, 2023). The ability to inhibit behavior and wait for rewards has been proposed to be serotonergic in nature, as serotonin is likely implicated in mediating aversive inhibition (Crockett, Clark, Apergis-Schoute, Morein-Zamir, & Robbins, 2012; Crockett, Clark, & Robbins, 2009; Geurts et al, 2013b).…”