Visual Reaction Time of Patients with Cerebral Disease as a Function of Length and Constancy of Preparatory Interval

Woodrow (1914), Klemrner (1956), and Karlin (1959) have demonstrated chat in normal adults reaction time (RT) is influenced by the duration of the foreperiod or preparatory interval (PI), i.e., the interval between onset of a warning signal and onset of the RT stimulus. Woodrow (1914) found char shorcest RTs were obtained with PIS of 2-sec. duration. Shorter or longer PIS led to RTs of increased length. The normal Ss tested by Rodnick and Shakow ( 1940) also gave evidence that a 2-sec. PI is optimal for RT. Other investigators failed to confirm this finding. They presented evidence thac RT increases with increase in the duration of PI, over a PI range of from .5 to 8 sec. (Klemmer, 1956) and from .5 to 3.5 sec. (Katlin, 1959). Investigation of the relationship of PI to RT has been extended to samples of schizophrenics (Hutson, Shakow, & Riggs, 1937; Rodnick & Shakow, 1940) and to aged patients (Brinley & Botwinic, 1959; Borwinic, Brinley, & Robbin, 1959). These investigators found that their schizophrenic and aged Ss did not respond most rapidly on the RT trials after PIS of 2 sec. or less, as did controls. Furthermore, their patient samples are described as being less able than normals to develop a set for, and respond to, a series of stimuli presented after constant PIS of long duration. While Blackburn and Bencon (1956) and Benton and Joynt (1959) have demonstrated thac RTs in patients with cerebral disease are longer than those of normals when a PI of 2 sec. is used, the effect of differing PIS on the RT of brain-damaged patients has not been reported. The present study is concerned with the following questions: (1) What is the relationship between PI and RT in a series of brain-damaged Ss and in comparable control Ss? (2) What are the effects of repeated trials on the PI-KT relationship? (3) Do control Ss perform more rapidly than brain-damaged Ss on RT casks with PIS other than 2 sec.?