Gentle stroking induces conditioned place preference in rats: Implications for animal welfare (2026)

Nagaishi, T., Shiomi, S.

Abstract

Gentle tactile interaction with humans has been proposed as a form of social enrichment for laboratory animals; however, its direct reinforcing properties remain underexplored. Therefore, this study tested whether brief, gentle stroking can function as a positive reinforcer in adolescent rats. We employed a within-subject conditioned place preference design consisting of two conditioning cycles, each comprising 10 alternating daily sessions, in which, on rewarded days, rats received three 1-min stroking epochs embedded within a 15-min compartment exposure (total stroking time: 3 min/day). The animals experienced alternating sessions of stroking on the experimenter’s palm or a neutral handling procedure. The results indicated that rats showed a reliable increase in preference for the stroking-paired compartment across conditioning, demonstrating that minimal tactile contact was sufficient to induce place conditioning. These findings suggest that structured human–animal tactile interaction can elicit motivated behavior and provide a practical refinement of routine handling protocols in laboratory settings to enhance animal welfare.