The renewal reducing effect of unpaired unconditional stimuli presented during extinction is not specific to the unconditional stimulus used during acquisition.

Presenting unpaired unconditional stimuli (US) during extinction training reduces the renewal of conditional fear due to context change. The present study investigated whether this reduced return of fear is specific to the aversive US presented during acquisition or can also be observed after extinction with unpaired presentations of another aversive or of a non-aversive US. Using an ABA renewal paradigm that trained extinction in a context different from that of the acquisition, renewal and re-acquisition test phases, participants received five unpaired presentations of either the aversive US used during acquisition (Group Aversive-Same), an aversive US not presented during acquisition (Group Aversive-Different) or a non-aversive US (Group Non-aversive) during extinction training. Renewal of electrodermal conditional responses was observed in group Non-aversive, but not in groups Aversive-Same or Aversive-Different. Re-acquisition did not differ across the groups. These results are consistent with a valenced arousal account to explain the effects of unpaired presentations of the US during extinction training which would suggest that extinction learning is enhanced under conditions of increased aversive arousal.