Magnification of visual feedback results in greater performance error when visual feedback is removed


Visual feedback is a rich source of information for improving human motor performance and provides a basis for the formation of memory to guide performance in the absence of visual feedback. According to the Guidance Hypothesis (Salmoni et al., 1984) dependence on visual information is affected by the amount of visual information provided. This study examined how varying amounts of visual feedback affect subsequent memory-guided performance. Healthy participants (N= 12) completed 20 s trials of isometric force with their index finger and thumb, equal to 25 % of their maximum voluntary contraction. Participants were shown a movable force bar that moved vertically in real-time to represent their force output. They were instructed to move the force bar to overlap a bar indicating the target amplitude. Visual feedback about their performance was provided for the first 8 s in one of three magnification levels. In the remaining 12 s of the trial, participants were instructed to maintain the same amount force in the absence of visual feedback. The results demonstrated that absolute error during memory-guided force production was greatest when the memory-guided portion of the trial was preceded by the highest magnification condition. This finding is consistent with the Guidance Hypothesis that suggests the performance can become dependent on greater amounts of visual feedback, negating the recognition and formation of their own intrinsic perceptions of the performance. Further, the current work suggests that the magnification of visual feedback can negatively influence the ability to form stable memories from which to guide performance.