Abstract
Significant neurobehavioural evidence suggests a discrete segregation between the pathways associated visual perception (i.e. ventral projections) and those ascribed visuomotor functions (i.e. dorsal projections; see Milner & Goodale 2008 for a recent review). In general, the dorsal stream appears specialized for processing veridical egocentrically coded cues in a fashion that is independent of conscious awareness (e.g., Binsted et al., 2007). Conversely, the ventral stream considers the relational characteristics of visual objects and scenes to arise at a rich percept. However, demonstrations of dorsal insensitivity to perceptually driven object features have failed to address valence as an evolutionarily viable action moderator. In the current investigation we utilize a variant of a Tipper attention paradigm (e.g., Tipper et al 2001; Welsh et al., 1999) to present distractor cues at offset, non-target locations; importantly, the non-target cues varied in perceived valence (i.e. positive, neutral, negative). Participants were to reach to a target image presented either alone or concurrently with non-target images of (a) a spider, (b) a flower or © scrambled pixels. In response to these manipulations, 12 participants demonstrated reliable distractor effects for reaction time, movement time and movement trajectory formation. Recorded movements were slower in the presence of all distractors - in both the planning and control phases (see Keulen et al., 2002). Importantly however, and contrary to a view of the perceptual isolation of action, participants demonstrated significant influence of distractor valence. Pointing movements were faster and more variable when made in the presence of a spider cue. Further, both the positive (flower) and the negative (spider) valenced cues demonstrated a reliable attraction effect on the movement trajectory. Thus, it appears that the visuomotor system is does not restrict its visual set, instead it appears to rapidly integrate perceptual interpretations of abstract scene cues (here line-drawings) for movement adaptation.
National Sciences and Engineering Research Council of Canada (GB, MH).