The kinesthetic threat eyeblink: a new type of anticipatory eyeblink response.

The present paper is part of a systematic exploration of naturally acquired conditioned eyeblink responses in human subjects. Normal human subjects were examined for the presence of anticipatory eyeblinks in a new paradigm. They were instructed to move their hand quickly toward their face and tap their forehead. In this situation, subjects generated anticipatory eyeblinks which were initiated before the forehead tap. Additional experiments revealed that visual stimuli and internal movement-planning cues are not required for the initiation of this response. The kinesthetic information from the passively moving arm, however, was sufficient to trigger this kinesthetic threat eyeblink response (KTER). The KTER extinguished when the forehead tap did not reinforce it. These data indicate that the KTER is a unique type of naturally acquired conditioned response system which is maintained by aversive reinforcing events.