The study purports to qualify the psychological information value of autonomic-somatic activity, the source of the traditional dependent variables of psychophysiology. This is done by verifying their ability to show situational specificity not only as response to realized events but also on the basis of mere mental representations of these events via anticipation. The demonstration of effects of overt situational demands is made by comparing the immediate responses produced by varied critical events. The situational specificity of the anticipatory response patterns is studied by recording the pre-event patterns of these same events while varying the advance information about them. Skin conductance, pulse amplitude, blood volume, heart rate, respiration, pupil dilation and three EMGs (flexor, frontal and orbicularis oris) were recorded from 112 Ss in two-event conditions in which the first event offered a varied amount of information about the second, critical event. Six types of critical events (sensory, motor and two cognitive tasks and two stimulus types) were presented in semirandom order to four groups of subjects. The amount and type of advance information given to the groups as the first event was systematically varied. The six events were shown to produce event-specific patterns. The most pronounced contrasts were between the main types of events, viz.cognitive, motor and sensory events. This specificity appeared already in the immediate responses to the first event in the most informed group and showed similarity to the responses produced by the critical event itself. Specificity also increased as a function of the amount of advance knowledge. This made it possible to examine it as an expression of anticipation. The advance information had an effect also on the event-produced response pattern, which verifies the phenomenon called preception by Lykken. Its known empirical manifestations were replicated. Several new aspects of the preception phenomenon and the evidence about anticipatory physiological responses and their patterning were introduced for discussion for the first time.