Pavlovian conditioning of the tickle response of human subjects: temporal and delay conditioning.

Previous studies of the human response to a tickle have demonstrated that subjects will respond to a gesture that signals the onset of a tickle in the same way as to a tickle. Researchers have described this anticipatory response as an "expectation." In the current study, we investigated, from the Pavlovian framework, the response to a verbal stimulus preceding the tickle stimulus. We exposed subjects to experimental phases which included the Neutral Stimulus Alone, 100% Pairing of the Neutral and Unconditioned Stimuli (tickle strokes to the foot), Random Presentation, Partial (75%) Reinforcement, and Temporal Conditioning. Pavlovian conditioning was observed in all phases, suggesting a parsimonious explanation for the expectation effect described by others.