An alternative test of the adams-creamer decay hypothesis in timing motor responses.

Ss were randomly assigned to either a vestibular proprioception (VP) group (N = 30) or a no vestibular proprioception (NVP) group (N = 30). The VP group was tested while supine on a table rotated 60 deg. in the vertical plane and, at the cessation of rotation, Ss estimated a 2-sec. interval. Procedures were identical for the NVP group with the exception that they received no body rotation. All Ss received 40 trials and knowledge of results was given during a 20-sec. intertrial interval. The VP group had significantly smaller mean absolute and algebraic error scores than the NVP group. The difference between the mean variable error scores of the two groups was not significant. Results supported the Adams-Creamer decay hypothesis in terms of absolute error scores and algebraic error scores, but did not support the hypothesis in terms of variable error scores.

Pre-motor and motor reaction time differences associated with stretching of the hamstring muscles.

Pre-motor and motor RT scores were obtained from 24 male Ss using a knee flexion task. It was predicted that an increased arousal state due to proprioceptive feedback from stretched hamstring muscles would shorten pre-motor RT while motor RT would shorten because of changes in muscle tension development due to changes in the series elastic and/or contractile components of the muscle tissue. A finger RT task was also included in order to determine whether other factors not related to changes in the stretch of the hamstring muscles were operative. Motor RT decreased with increased muscle stretch and constituted 46% of leg RT. Pre-motor RT as well as finger RT increased rather than decreased with increased muscle stretch. No relationship was found between pre-motor and motor RT indicating that lags in CNS processing are independent of lags associated with the rate of muscular tension development.