Are Object Affordances Fully Automatic? A Case of Covert Attention

Inspired in part by Gibson's (1979) ecological approach to perception, current neurocognitive theories of action suggest that the simple viewing of an object can automatically elicit motor programs for specific acts. However, the degree to which such affordances should be considered truly automatic is unknown. Here we explored the generation of motor plans afforded by pairs of cue objects that were viewed peripherally under different attentional states. Participants focused centrally while attending to just one of two peripheral cue objects that together had a strong significance for pinching, grasping, or both. They were instructed to ignore the objects and instead give power or precision grip responses to subsequent changes in background color. The data showed a significant interaction between type of response and type of object, indicating that object affordances are perceived even in nonfoveal vision. Critically, the generation of affordances was modulated by the locus of attention: Motor preparation was biased toward the attended object when two different categories of object appeared in the same trial, but the generation of affordances was also influenced by unattended stimuli. This finding demonstrates that object-action priming is not completely automatic, instead being constrained by processes of perceptual selection.