[Psychometric effects of perphenacine below the "neuroleptic threshold" (author's transl)]

The extrapyramidal-motorical side effects of neuroleptic drugs are preceded by subtle symptoms, the assessment of which is dependent on the methods used. For the evaluation of several such methods of assessment we compared the results of the handwriting test (Haase, 1969) with EMG-measurements of the silent period and psychometric measurement of aiming-, tapping-, and reaction-time-tests. Twenty normal subjects were tested four times in a double blind study in order to control the short- and long-term effects of a low dosage of perphenacine. Slight but significant drug-dependent changes were found, such as decreases of steadiness and of the speed of arm-hand-movements. From the theoretical point of view these results support a dimensional approach rather than an explanation in terms of a categorial approach as it is suggested by the commonly used notion "neuroleptic threshold".