Rule-based generalisation in single-cue and differential fear conditioning in humans

•Fear generalisation in humans was tested in both single-cue and differential conditioning paradigms.•Participants reported a range of rules.•Generalisation gradients were highly consistent with reported rules.•Results favour a single-system account of learning.

Fear generalisation refers to the spread of conditioned fear to stimuli similar but distinct from the original conditioned stimulus. In this study, participants were presented with repeated pairings of a conditioned stimulus with a shock, in either a single-cue or differential conditioning paradigm. Generalisation of fear was then tested by presenting stimuli that were novel, but similar to the conditioned stimulus along a spatial stimulus dimension. Dependent measures were online shock expectancy ratings and skin conductance level. A diverse range of generalisation gradients was observed, and the shape of the gradients for both expectancy ratings and skin conductance responses corresponded with participants' verbally reported rules. The findings point to an important role for cognitively controlled processes in human fear generalisation, and provide support for a single-system learning model. They also highlight the potential importance of cognitive reappraisal in clinical treatments for over-generalised fear.