The simple reaction time (RT) is studied for two groups of schizophrenic and normal subjects in order to clarify their “adaptability” to the simple task. The visual stimulation of constant interval (2 sec or 3 sec) is continuously imposed on the subject for about 10 minutes. The measurement of RT and the calculation of statistical quantities are carried out by using a measuring system made up of a microcomputer and some electronic circuits. Significant differences could be found between these two groups in the average value <RT>, standard deviation SD, serial correlation coefficient R₁, and abnormal RTs far-off <RT>. The reason of the difference is examined by other experiments including anticipation or preparation. As a result, the above difference can be understood to have arisen from the fact that schizophrenics have lower adaptability than normal subjects.