Do manufactured and natural objects evoke similar motor information? The case of action priming

There is considerable evidence that visually presented manipulable objects evoke motor information, supporting the existence of affordance effects during object perception. However, most arguments come from stimulus-response compatibility paradigms, raising the issue of the automaticity of affordance effects. Action priming paradigms overcome this issue but show less reliable results, possibly because affordance effects are moderated by additional factors. The present study aimed to assess whether affordance effects highlighted in action priming paradigms could be affected by object category (manufactured or natural). A total of 24 young adults performed a semantic categorisation task on natural and manufactured target objects presented after neutral (non-grasping hand postures) or action (congruent power or precision grips) primes. Results revealed a modulation of action priming effects as a function of object category. Object semantic categorisation was faster after action than neutral primes, but only for manufactured objects. Results suggest that natural and manufactured objects evoke distinct types of affordances and that action priming paradigms favour the evocation of functional affordances during object semantic categorisation. This finding fuels the debate on the nature of the motor information evoked by visual objects.