Unconscious Presentation of Object Affordances Evokes a Negative Compatibility Effect

According to Gibson's (1979) theory of “affordances”, the environment is constantly bombarding the viewer with a multitude of possible actions. More recently, it has been suggested that the simple viewing of an object can automatically elicit motor plans for actions towards this object. Research has attributed this phenomenon to the existence of two different neural pathways for processing visual information from objects and implied a distinction between conscious visual perception (meditated by the ventral stream) and unconscious visuomotor control (sub-served by the dorsal stream). This has proved compelling to many researchers, who have further tried to dissociate conscious visual perception from visually guided performance. In the present study, participants formed precision and power grips in response to a central colour stimulus, in order to determine whether these actions could be modulated by the prior subliminal presentation of pinch/grasp affording prime objects. All prime objects were briefly presented for 20 ms, thus making it impossible for participants to consciously identify these. A mask followed the prime's initial onset, after which the target was presented. The time between the onset of the prime and the appearance of the target was, also, varied in order to assess the time course of any priming effects obtained. The results suggest that affordances for relevant actions can also be extracted from objects whose physical properties are far from obvious, and appear inaccessible to consciousness. Furthermore, we provide evidence of a negative compatibility effect under experimental circumstances that have not been described in the literature before, and which rule out many kinds of interaction at a perceptual level.