Perceiving objects by their function: An EEG study on feature saliency and prehensile affordances

•Study of the feature saliency and motor affordance effects induced by photos of objects.•The feature saliency effect is dominant when no instruction is given.•Premotor suppression of beta rhythm correlates with the feature saliency effect.•EEG analysis suggests the presence of a behaviorally masked motor affordance effect.

We examined the feature saliency and prehensile/motor affordance effects that are visually elicited by a graspable object’s most salient features and graspable part, respectively. EEG was recorded from participants who attended a photo of an object, and responded to a left- or right-pointing arrow, which was overlaid on the object 1000 ms after object onset. Analysis of response times demonstrated the presence of a feature saliency effect. Lateralization of posterior alpha suppression showed that attention was initially directed to the object’s (most salient) functional end. Pre-movement frontocentral beta suppression and the modulation of the P3 component showed that a response compatible to the functional end was activated before arrow onset. Moreover, lateralization of pre-movement posterior and central alpha suppression indicated a behaviorally masked affordance effect. This suggests that the two effects may occur independently, but without specific attention orienting instructions, the feature saliency effect dominates a potential prehensile affordance effect.