PRELIMINARY STUDY OF THE EFFECTS OF POST-RETRIEVAL EXTINCTION ON THE RETURN OF CONDITIONED RESPONSES IN HUMANS

Abstract

We conducted a preliminary study to replicate the experiment by Schiller et al. (2010), who found that conditional responses (CR) may be permanently inhibited through post-retrieval extinction, a procedure in which subjects are exposed to a stimulus that was present during conditioning (retrieval cue), such as the presentation of the CS without the US or a single presentation of the US alone, followed by extinction. Eleven adult participants underwent Pavlovian conditioning with three colored squares (CS), two of which (CSa+ and CSb+) were paired with a mild electrical stimulation (US), whereas a third stimulus was never paired with a US (CS-). Twenty-four hours later, the participants were divided into two groups (experimental and control) and underwent extinction, which consisted of presenting all CSs without the US. For the experimental group only, a retrieval cue consisting of a single presentation of the CSa+ and CS- without the US was administered 10 min before extinction. In the test phase, the US was administered four times and then followed by a ten-minute interval and a new extinction procedure. Skin conductance responses to the stimuli were measured. Groups did not differ from each other. They presented equivalent levels of conditioning and extinction as well as an increase in CR amplitudes following the presentation of all stimuli in the test phase. These data do not replicate findings from the original study, suggesting that further analyses are needed to identify variables that control Pavlovian conditioning and extinction in humans. Key words: Pavlovian conditioning, post-retrieval extinction, reconsolidation, skin conductance, humans.