RESUMEN
Several studies have demonstrated that either chromatic or spatial information can guide motor behaviour, but so far interactions between these two visual features are little understood. Here we addressed this issue by measuring reaction times (RT) for pointing hand movements which were instructed by either cues for spatial (thought to be predominantly processed in the dorsal visual stream), colour (thought to be predominantly processed in the ventral visual stream) or redundant (combination of colour and spatial information) conditions. While faster responses were found for spatial than for colour cues, most importantly, the shortest RTs were measured for the combined cues (redundancy signal effect, RSE). The data are inconsistent with the predictions of the race model which assumes parallel and independent input from the two streams to the motor system. Instead, the data are better explained by the coactivation model, which proposes combined sensory information from the different stimuli and detection process from the sum of the signals. Here, the redundancy signal effect results from the combination of colour and spatial information. The results provide behavioural evidence for an integration of colour and spatial cues when guiding hand movements.