Developmental vision determines the reference frame for the multisensory control of action

Abstract

Both animal and human studies suggest that action goals are defined in external coordinates regardless of their sensory modality. The present study used an auditory-manual task to test whether the default use of such an external reference frame is innately determined or instead acquired during development because of the increasing dominance of vision over manual control. In Experiment I, congenitally blind, late blind, and age-matched sighted adults had to press a left or right response key depending on the bandwidth of pink noise bursts presented from either the left or right loudspeaker. Although the spatial location of the sounds was entirely task-irrelevant, all groups responded more efficiently with uncrossed hands when the sound was presented from the same side as the responding hand ("Simon effect"). This effect reversed with crossed hands only in the congenitally blind: They responded faster with the hand that was located contralateral to the sound source. In Experiment II, the instruction to the participants was changed: They now had to respond with the hand located next to the sound source. In contrast to Experiment I ("Simon-task"), this task required an explicit matching of the sound's location with the position of the responding hand. In Experiment II, the congenitally blind participants showed a significantly larger crossing deficit than both the sighted and late blind adults. This pattern of results implies that developmental vision induces the default use of an external coordinate frame for multisensory action control; this facilitates not only visual but also auditory-manual control.

Fig. 1.

Group mean IE scores with standard errors of the means in Experiments I (Simon task, a and c) and Experiment II (b and d) for the congenitally blind and their control group (a and b) and the late blind and their control group (c and d). IE scores are calculated by dividing RTs by correct response rates, thus eliminating any potential speed-accuracy tradeoff effects in the data; the lower the score, the more efficient/better is performance (i.e., analogous to the RT data) (19, 36). Experiment I (a and c): With hands uncrossed, all groups showed a similar pattern of inferior performance in the noncorresponding compared with the corresponding condition. This effect reversed in the congenitally blind only when their hands were crossed (with respect to an external coordinate system). All of these groups, except the congenitally blind, activated an external reference frame by default. Experiment II (b and d): When the congenitally blind had to match sound and hand locations, interference due to hand crossing was larger than in the remaining groups. It is possible that only the congenitally blind had to inhibit their default anatomical reference frame and activate an external reference frame, whereas the latter had automatically been activated by default in the remaining groups. Note the different scales.

Fig. 2.

Experiment I: Inverse efficiency scores for individual participants: sighted controls for the congenitally blind (a), the congenitally blind (b), sighted controls for the late blind (c), and the late blind (d). Note that only the congenitally blind participants showed a reversed Simon effect with their hands crossed. Note the different scales for a and b vs. c and d. Late blind participants 01 and 02 had been totally blind for 34 and 50 years, respectively.