Does the time-span of conditioning affect spontaneous recovery after extinction?

Gold-standard psychological treatments such as exposure therapy are significantly undermined by high relapse rates. Although exposure-based treatments are capable of extinguishing maladaptive behaviours, these behaviours often spontaneously re-emerge over time – a phenomenon known in experimental research as spontaneous recovery. Understanding the factors that underlie this process is essential to improving long-term treatment outcomes. One factor that is yet to be properly examined is the effect of the total span of time across which behaviours are learned. To date, only one study by Gallistel & Papachristos (2020) has explored this in mice. Their findings suggest that long spans of acquisition learning result in greater spontaneous recovery compared to short spans. We investigated the effect of conditioning span across 5 experiments using rats. Contrary to Gallistel & Papachristos, our results found no difference in recovery between rats conditioned over a long span versus a short span, following short, intermediate and long delay intervals. This suggests that the span of conditioning does not affect the magnitude of recovery, nor the rate at which recovery emerges. Unexpectedly, conditioning span did appear to influence the strength of responding during acquisition, such that longer conditioning spans led to higher levels of responding. This finding could indicate that the learning process operates over a long time period beyond the original training episode. However, further research is needed to establish whether conditioning span influences the strength of what is learned, or instead the performance of a conditioned response. •Conditioned responses can spontaneously recover after extinction, a phenomenon likened to relapse after exposure therapy.•Our study pursued recent evidence that the timespan across which behaviours are learned can affect spontaneous recovery.•We found that conditioning span did not affect the size of recovery or how quickly responding re-emerged after extinction.•Span did affect the amount of responding acquired, suggesting the learning process extends beyond the conditioning session.