Within-subject covariation of reaction time and foreperiod cardiac deceleration: effects of respiration and imperative stimulus intensity

The warned foreperiod reaction time (RT) task is claimed to provide data supportive of the Lacey's visceral afferent feedback theory. However, although there are many reports of significant between-subject correlations between heart rate (HR) and RT, more direct tests examining within-subject covariation show, at best, inconclusive results. These studies suggested several procedural refinements which could produce stronger within-subject relationships. The procedures adopted in this investigation included manipulating attentional involvement by varying imperative stimulus (IS) intensity, using a respiratory control and a repeated measures design, recording electromyographic RT, employing a contact switch manipulandum with no moving parts, and having subjects initiate trial presentation. 40 males were divided between normal breathing and hold breath groups. Subjects received three blocks of 24 trials with the IS at either 10, 50, or 80 db. A variety of measurement and statistical approaches yielded generally negative results, with an overall mean within-subject correlation in the predicted direction of -0.06.