Figure 6.

Removal of visual feedback ameliorates age-associated differences in motor output variability during sinusoidal tasks. Young (white bars) and older (black bars) adults practiced sinusoidal movements with abduction-adduction of the index finger. The amount of visual feedback was 5.4 degrees. Following every block of five trials (a total of eight blocks in the practice session), young and older adults performed the sinusoidal task from memory (target was present but not their movement trace; thus, visual feedback was not available). During the practice trials with visual feedback (left panel), older adults exhibited greater movement variability than young adults (data adapted from (8)). In contrast, during the memory trials, movement variability in older adults decreased to the level of young adults. These results suggest that visual feedback is instrumental in amplifying motor output variability in older adults during movements.