[Quantitative pupillometric determination of sensitivity to pain (author's transl)]

1. Pain-induced pupillary dilatation was investigated by means of a method which compensates for the pupillary light reflex. Electric pain stimuli of varied intensity were applied to the forearm. Pure tone (T), pure pain (S) and combined tone-pain (TS) stimuli were used in stochastic or periodic succession. 2. The amplitude of pupillary dilatation increased in the order T, S, TS, In these experiments the sum of the T and S reactions is lower than the TS reaction, in contrast to summation patterns in other nervous structures. The amplitudes of pupillary dilatation and the intervals between stimuli and maximal dilatation increased linearly with increasing stimulus intensity. The latency period, however, is not systematically influenced by the intensity of the stimuli. Adaptation is delayed by stochastic application of the stimuli.