A move towards studying both pavlovian & instrumental contributions to conditioning abnormalities in the anxiety disorders

Abstract

Fear-conditioning experiments in clinical anxiety have focused almost exclusively on passive- emotional, Pavlovian conditioning, rather than active-behavioral, instrumental conditioning. Paradigms capable of eliciting both Pavlovian and instrumental conditioning are thus needed to experimentally study the maladaptive behavioral consequences of Pavlovian abnormalities. One such abnormality is overgeneralization of conditioned fear, a core feature of anxiety pathology. Such generalization can be assessed by studying generalization gradients and until now has only been examined using Pavlovian conditioning. The current study validates a novel paradigm which applies a validated Pavlovian generalization experiment in the context of a `virtual farmer' computer game in which the participant is a farmer whose task it is to successfully plant and harvest crops. While playing the game, shapes are superimposed on the screen with one such shape, paired with shock, serving as the conditioned danger cue (CS+). Generalization stimuli (GS), parametrically vary in similarity to the CS+, but are never paired with shock. While playing the game, participants are given the opportunity to avoid shock (instrumental conditioning) at the cost of poorer performance. Fear-potentiated startle (FPS), skin conductance responses (SCR) and online risk ratings were obtained and each displayed the expected Pavlovian generalization gradient. Instrumental avoidance responses also form a generalization gradient and are strongly associated with Pavlovian indices of generalization (FPS and risk ratings but not SCR). Additionally, FPS at acquisition was a significant predictor of subsequent avoidance behavior. This novel experimental tool will be useful in describing and testing individual differences associated with clinical anxiety.