Online and in-person stress induction in a quasi-avoidance-based Pavlovian-to-instrumental transfer task

Pavlovian instrumental transfer (PIT) is a phenomenon in which a conditioned stimulus (CS), previously paired with a specific outcome, can influence performance of an instrumental response (R). PIT can be specific (the CS selectively elevates performance of an R paired with the same outcome as that CS) or general (CSs elevate performance of an R paired with any outcome of the same motivational value). PIT has been proposed as a mechanism underlying maintenance of addictive behaviours, while exposure to stressors is regarded as a risk factor for the development, maintenance and relapse of addiction. Thus, we used a quasi-avoidance-based PIT task to explore whether stress can influence the magnitude of specific or general PIT effects. We used stress induction procedures to elevate stress levels. These were either conducted online, exposing participants to negative pictures and heavy metal music (Experiment 1), or in person, telling participants they had to give a speech which would be filmed (Experiment 2). In neither experiment could we detect any effect of higher stress levels on specific or general PIT. The results do not support the proposal that stress influences the size of PIT effects in human participants.