Eight men and 8 women came to the laboratory on 3 occasions, 1 wk. apart, to receive 10 presentations of a visual stimulus on each occasion. The average GSR (galvanic skin response) to the light showed an intrasession (but no intersession) adaptation effect for both sexes but this effect was almost gone for the males on the last session. In addition, the males made significantly larger GSRs than the women on all 3 sessions, especially on the last session. It was conjectured that the men became familiar with the procedure and anticipated the end of the 3rd session by making larger GSRs, but that the women did not.