Simple reaction-times to speech and non-speech stimuli.

Two experiments were carried out involving the measurement of simple reaction-time when subjects responded to speech and to non-speech stimuli. In the first, subjects were required to make a speech response (uttering the vowel [a: ]) to one speech stimulus (the vowel [a: ]) and three non-speech stimuli (a complex tone, a telephone bell and a click). The click stimulus gave significantly longer reaction-times than the other three stimuli; since all stimuli were equated for peak intensity delivered to the subjects' ears, this was due to the short duration of the click (25 msec). There was no evidence that compatibility between the speech stimulus and the speech response had any influence on reaction-time. The second experiment employed a 2 X 2 design with 2 stimuli and 2 response modes. The stimuli were the vowel [a: ] and the telephone bell; the response modes were key-pressing and uttering the vowel [a: ]. The speech stimulus and the speech response gave significantly longer reaction-times than the non-speech simtulus and response. The minimum time for a reaction requiring speech reception is of the order of 180 msec. and the use of the motor speech mechanism adds about 30 msec. to reaction-time. Again no interaction was found between stimulus and response and this is probably due to the extremely simple nature of the speech tasks imposed.