Habituation of the galvanic skin response in adult males as a function of age.

Habituation of the galvanic skin response (GSR) to electric shock was studied in 28 male college students, 18-39 years old. A 60-Hz shock of 244.0-msec duration was presented every 1-3 min above the right ankle in a preprogrammed sequence. The GSR, measured as a change in palmar skin conductance to the shock, was examined over the first 17 shock trials. The habituation curve showed the typical large decrement over the first few trials followed by a smaller one over several more trials. The initial rate of habituation (percent decrement between shock trials 1 and 3) was shown to be age related even though none of the subjects would be considered old (18-39 years old). The younger the subject, the faster the initial habituation or, conversely, the older the subject the slower the rate (rs = -.50, N = 28, p less than 0.005). The asymptote did not vary with age. That such dramatic changes occur in the CNS of young males over a relatively few years is not unknown. PET studies of the caudate nucleus in normal males showed an exponential decrease in dopamine receptors with about half of the decrease occurring rapidly between the ages of 20 and 30 (Wagner, H.N., Jr. Diag. Imaging Nov.: 138-145; 1985). The usefulness of the GSR in detecting age effects in other kinds of learning, such as Pavlovian conditioning, is being explored, as well as its usefulness in detecting early learning/memory loss in aging and the dementias.