296 D. Papakostopoufos, ed. / Psychophysiofogy Socieiy Abstracts, I982

CHANGES IN CARDIAC AND MUSCLE ACTIVITY DURING A FIXED FOREPERIOD IN A SIMPLE REACTION TIME TASK

S.A.V.M. HAAGH

Depurtment of Psychology, Tifburg University, The Netheriunds

Obrist, Webb, Sutterer and Howard (1970) assume that a decrease in heart rate prior to an imperative stimulus is part of a general inhibitory process and is accompanied by a decrease in response-irrelevant muscle activity. To in- vestigate this somatic inhibition a simple auditory reaction time experiment was conducted in which a plantar flexion of the right foot served as the response. The foreperiod (FP) duration was 4 set; the variable intertrial interval had a mean duration of 15.5 set (range 11-20 set). Fourteen right handed subjects were run in the experimental session which consisted of 50 trials. The EMG of the following muscles was recorded: (1) Response-relevant - right soleus muscle and tibialis anterior (TA) muscle; (2) response-irrelevant - left soleus muscle, left TA muscle, left mylohyoideus muscle, and horizontal and vertical movements of the left eye.

As was previously reported by Obrist et al. (1970), the results showed that the number of eye movements, the mylohyoideus EMG and the heart rate decreased towards the end of the FP. In addition an increase of the EMG of the right soIeus and TA muscle was found. However, the response-irrelevant activity of the left soleus and TA muscle did not decrease during the FP. Therefore these data do not unequivocally support the cardiac-somatic cou- pling hypothesis.

Reference

Obrist, P.A., Webb, R.A., Sutterer, J.R. and Howard, J.L. (1970). The cardiac-somatic relation-

ship: Some reformulations. Psychophysiology, 6, 569-587.

BLINK REFLEX MAGNI~DE PRIOR TO A VOLUNTARY MOVEMENT THE EFFECT OF PRECUEING

A.J.W. BOELHOUWER, E. BRUGGEMANS and C.H.M. BRUNIA

Physiofogtcal Psychofogv Section, Tilburg University, Tilburg, The Netherlands

It has already been observed that the early component (R,) of the blink reflex is enhanced during the foreperiod (FP) of a warned reaction time task,

D. Papakostopoulos, ed. / Psychophysiology Society Abstracts, 1982 297

while the bilateral late component (R2) is lower as compared to control reflexes (Boelhouwer, 1982). In the present experiment the effect of response precueing on blink reflex magnitude during a 3 set FP was studied. One group of 16 well-trained subjects reacted after the reaction signal (RS) with a voluntary blink when the warning signal (WS) was a high tone (p = 0.5). No reaction was required when WS was a low tone ( p = 0.5). WS thus served as a precueing stimulus at the beginning of FP. Another group of 16 well-trained subjects reacted contingent on RS, i.e. a voluntary blink was required when RS was a low tone (p = 0.5), while no reaction was required whenever RS was a low tone ( p = 0.5).

Within 300 msec after WS a transient increase of R, was always seen in both conditions. The increment, however, was more pronounced when WS was the precueing stimulus. During the second part of the 3 set FP, R, increased maximally when in the precueing condition a response had to be given and almost no increase was seen when no response was required. In the no-precue- ing condition an R, increment was always present, although not as large as in the precueing condition when a response was required. R, decrement was pronounced immediately after WS. During the remainder of FP a slight decrease below baseline level was observed. The effect of precueing was not so clearcut as it was for R,.

Reference

Boelhouwer, A.J.W. (1982). Blink reflexes and preparation. Biological Psychology, 14, 277-285.

CHANGES IN ACHILLES TENDON REFLEX AMPLITUDES AND IN HEART RATE DURING A FOREPERIOD OF 4 SEC, PRIOR TO AN IMMEDIATE AND TO A DELAYED RESPONSE

C.H.M. BRUNIA, E.J.P. DAMEN and A.C. VAN DIEREN

Department of Psychology, Tilburg University, The Netherlands

In previous experiments Achilles tendon (T) reflexes were recorded bilater- ally during the fixed 1 or 4 set foreperiod of a simple warned reaction time experiment. If the response is a plantar flexion of either foot, T reflexes ipsilateral to the movement side are evoked via the same motoneurons, by which the voluntary movement is realized. During the foreperiod T reflex