Early selective attention effects on cutaneous and acoustic blink reflexes

In two experiments, selective modulation of the human blink reflex was examined by direct­ ing subjects to judge duration of the startling or nonstartling member of an acoustic-cutaneous stimulus pair, and Hillyard and Naatanen suggested that a selective state was "already prevailing" at the moment of stimulus de­ livery.

Abstract

In two experiments, selective modulation of the human blink reflex was examined by directing subjects to judge duration of the startling or nonstartling member of an acoustic-cutaneous stimulus pair. The startling stimulus was acoustic in the first experiment and cutaneous in the second. In both experiments, magnitude and onset latency were facilitated when the subjects attended to rather than away from the reflex-eliciting stimulus, although changes in cutaneous reflex size were insignificant. However, a nonselective inhibition of blink magnitude on warned relative to unwarned trials, associated with latency facilitation of the cutaneous reflex, was a stronger effect. The existence of both selective, concordant and nonselective, discordant changes in latency and magnitude could not be explained by a single mechanism. Heart rate changes also suggested that warning initiated some process in addition to attention to intake. The predictability of warned events may play a larger role than has previously been recognized.