| Popis: |
A substantial part of reaction time (RT), the time elapsed between presentation of a stimulus and the subject’s response, reflects a central delay during which the brain processes the input and elaborates a response. Low stimulus intensity, inefficient central processing, and lack of motivation are among factors which prolong RT. RT was readily measured in 34 children, age 5½ and older, attending a school for the deaf. Rapid responses to light and light plus sound, and all responses to sound alone were rewarded. Four of twelve children initially unresponsive to sound learned to respond. When sound was attenuated, plots of RT gave information on the efficiency of responses to suprathreshold stimuli and warned that threshold was approaching 5–10 dB before it was reached. Such curves would increase the face validity of clinical audiometric threshold estimates. In severely deaf children, somatosensory stimulation by 500-Hz tones yielded RT curves and thresholds which were very similar to those obtained with aural presentation of the sound, casting doubt on the auditory origin of residual hearing in the low frequency range. Somatosensory stimulation by 1000- and 2000-Hz tones was rare. |
