Perstimulatory adaptation as measured by reaction time: asymmetry between 400 and 500 kc/s.

The finger-withdrawal reaction time (RT) of 22 normal-hearing young adults was measured to 40 presentations of test tones of .5 kc/s and of .4 kc/s at 50 db SPL. An adapting tone of .4 or .5 kc/s at 50 db SPL was then presented, and after 7 min, RTs were collected to a series of 40 test tones as in the pre-adaptation procedure. The adapting tone-test tone order of .4-.5 kc/s, respectively, and the reverse order, were counterbalanced among Ss. In this study, as reported previously (Davis and Weiler, Brit. J. Audiol., 1976, 10, 102-106), RT changes were significant as a function of adaptation, but only in the order .5-.4 kc/s. Further study would be required to determine whether cochlear or more central processes are responsible for adaptation at .5 kc/s affecting RT at .4 kc/s, but for adaptation at .4 kc/s not significantly affecting RT at .5 kc/s.