A Motor Recalibration Influence on Color-Motion Asynchrony (CMA) in a Visuo-Motor Paradigm

Melisa Kurtcan & İnci Ayhan

CMA refers to an apparent perceptual asynchrony of visual features when repeatedly oscillating moving dots change colour and motion direction simultaneously at the same rate (Moutoussis & Zeki, 1997). It has been demonstrated that a single direction change is enough to induce CMA in cross-feature correspondence tasks (Linares & Lopez-Moliner, 2006). Following a recent study, where Stetson et al (2006) have shown a reversal effect in the subjective order of simultaneous action and sensation after subjects were adapted to a delayed sensory feedback regime, here, we examined whether such visuo-motor temporal recalibration is sensory-feature-specific and transferrable to multi-feature-stimuli in correspondence tasks such as CMA. We first measured the effect of visuo-motor recalibration in an experiment where subjects judged the temporal order of a voluntary key-press and a change in the motion direction of an achromatic dot array following a delayed (~100ms) sensory feedback adaptation in response to causal action. For those of subjects, who showed significant adaptation effects, we then conducted the main experiment using a single-direction-change CMA paradigm, where direction change was induced by voluntarily generated key-press and subjects were asked to report the predominant motion direction of target colour. Compared to baseline condition, we found that CMA was significantly reduced for the delayed sensory feedback adaptation condition. Control experiments showed that visuo-motor adaptation effects are not observed when the change in direction occurred independent of subject’s key-press, which together show a temporal recalibration effect in a visuo-motor CMA paradigm due to voluntary action.