Systematically investigating the role of context on effect replicability in reinstatement of fear in humans

Context is crucial in guiding behavior in an ever changing world and contextual information plays a crucial role in associative learning processes. For instance, the return of fear (RoF) after reinstatement (i.e, re-exposure the unconditioned stimulus (US) after successful fear extinction) is context dependent and is suggested to occur only when either extinction and test, or extinction and reinstatement context are identical, not when US re-exposure (i.e., reinstatement) occurs in a context different from extinction and test. Human adaptions of reinstatement paradigms have resulted in mixed findings: CS specific as well as unspecific RoF or unexpected “reinstated” conditioned responding in no reinstatement US control groups. Here, we systematically investigate the role of context on reinstatement-induced RoF in a human differential fear conditioning paradigm using subjective and psychophysiological measures in a large sample (N=212) including reinstatement and control groups. Overall, response patterns in reinstatement-groups mirrored results from single-cue rodent work. Yet, only generalized, not differential RoF was observed. Remarkably, depending on outcome measure RoF was also observed under identical experimental context conditions without US-re-exposure, underlining effects of contextual change beyond the reinstatement-US and challenging reinstatement research in human subjects and what we think we know about the mechanisms behind the reinstatement-phenomenon.