ABSTRACT

Sensory input that produces specific excitatory or inhibitory effects or that triggers movement can be classified as a stimulus. When sensory input, rather than provoking an output, undergoes processing to extract its meaningfulness in order to compose or adjust movements, it can be categorized as information. The output initiated by trigger stimuli is fixed and of short latency; that initiated by information is delayed, because of the processing time needed to extract meaning. The effect of information input on movement is much more complex and less predictable than that of trigger stimuli. Sensory stimuli must be processed to extract their information-carrying qualities, and this information can then be used to compose movement commands. Stimulus-processing delays precede movement, so that elaborate sensory perceptions come to serve as triggers for behavioral programs that are played out with only modest adjustment and updating via rapid reflex loops.