Timing a one-handed catch II. Adaptation to telestereoscopic viewing

A pre-exposure, exposure, post-exposure design was used to assess the adapt ation of the timing of a one-handed catch during telestereoscopic viewing. More specifically, it was examined whether the adaptation involved: (1) ign oring binocular sources of information and selecting other information, or (2) a recalibration of the coupling between the effected binocular informat ion and the catching movement, and (3), if it is recalibration, whether it is restricted to the manipulated binocular information. To test these hypot heses, subjects (n=16) were as signed to one of two groups, each group perf orming three blocks of 15 trials in the dark with only the ball visible. In the exposure condition, both groups were required to catch balls under bin ocular telestereoscopic viewing. In the pre-exposure and post-exposure cond itions, subjects performed under binocular and monocular viewing, respectiv ely. Kinematics of the grasping movement were recorded. It was predicted th at, in the case of a selection process, no aftereffects would occur in the post-exposure condition, whereas, in the case of recalibration, aftereffect s would occur. Moreover, if the recalibration is restricted to the manipula ted information, only the group that was provided with binocular vision dur ing the preexposure and post-exposure conditions would show aftereffects. S ignificant condition (pre-exposure, exposure, post-exposure) by block (firs t three trials, last three trials) effects were found for the moments of gr asp onset, peak opening velocity and hand closure, indicating that the hand was opened and closed earlier in the first three trials of telestereoscopi c viewing. This coincided with an in-crease in catching failures. In additi on, for the moments of hand closure and peak closing velocity, negative aft ereffects were found in the post-exposure condition. The hand was closed la ter in the first three trials after removal of telestereoscope. With respec t to the presence of the aftereffects, no differences were found between th e groups. It was concluded that adaptation to telestereoscopic viewing in t he timing of a one-handed catch is due to the recalibration of the coupling between information and movement, rather than a selection of another sourc e of information. Moreover, it is likely that the recalibration was not res tricted to the single, manipulated information. Rather, the recalibration i nvolves multiple binocular and monocular optical and oculomotor sources of information.