Feedback and instructional effects in the voluntary control of digital pulse amplitude.

The effects of verbal instructions and these instructions plus visual analogue feedback on the voluntary control of digital amplitude were examined in 2 groups of 8 subjects over 8 training sessions. Control of pulse amplitude was demonstrated but feedback did not add consistently or reliably to the effect of verbal instructions. Control did not improve over the period of training nor did it become more specific, i.e. the effect did not become localised at the feedback site and pulse interval, respiration rate and forearm muscle activity were implicated in the response throughout. The results are interpreted as providing little support for the theory that learning to control a visceral response is analogous to learning a motor skill.