Abstract
Objects are said to automatically “afford” various actions depending upon the motor repertoire of the actor. Such affordances play a part in how we prepare to handle or manipulate tools and other objects. Evidence obtained through fMRI, EEG and TMS has proven that this is the case but, as yet, the temporal evolution of affordances has not been fully investigated. The aim here was to further explore the timing of evoked motor activity using visual stimuli tailored to drive the motor system. Therefore, we presented three kinds of stimuli in stereoscopic depth; whole hand grasp objects which afforded a power-grip, pinch-grip objects which afforded a thumb and forefinger precision-grip and an empty desk, affording no action. In order to vary functional motor priming while keeping visual stimulation identical, participants adopted one of two postures, with either the dominant or non-dominant hand forward. EEG data from 29 neurologically healthy subjects were analysed for the N1 evoked potential, observed in visual discrimination tasks, and for the N2 ERP component, previously shown to correlate with affordances (Proverbio, Adorni, & D’Aniello, 2011). We observed a link between ERPs, previously considered to reflect motor priming, and the positioning of the dominant hand. A significant interaction was detected in the left-hemisphere N2 between the participants’ posture and the object category they viewed. These results indicate strong affordance-related activity around 300ms after stimulus presentation, particularly when the dominant hand can easily reach an object.
Highlights
The term affordance was first introduced by JJ Gibson in 1977 who suggested that just by viewing an object we perceive how to use it
PO3 and PO4, the posture by hemisphere by stimulus category (2x2x3) ANOVA revealed no difference between postures, nor between hemispheres, nor stimulus categories and there were no significant interactions
T-tests showed no significant differences between whole hand grasp objects and pinch-grip objects, p =
Summary
The term affordance was first introduced by JJ Gibson in 1977 who suggested that just by viewing an object we perceive how to use it. In recent years it has often been used to describe the idea that even when there is no intention to act, the intrinsic properties of an object will potentiate motor planning. This has prompted many studies investigating the existence of affordances (i.e. automatic priming of the motor system by viewed objects) in both human and non-human primates (e.g. Grezes et al 2003; Murata et al 1997; Rice et al 2007; Tucker & Ellis 1998; Tucker & Ellis 2001; Valyear et al 2007). Though, the 24 visuomotor neurons discharged when the animal viewed objects whether or not it was a ‘pick-up’ trial. It was concluded that the visuomotor neurons were responding to the visual features of each object, reaffirming the theory that intrinsic visual properties potentiate motor planning
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