Masking of Cutaneous Sensations in Multiple Stimulus Presentations

Abstract

Ten Ss made absolute judgments of electrocutaneous stimuli consisting of from one to three simultaneous stimulations of six loci. There were three loci in symmetrical positions on either side of S's body—one on each shoulder blade, one on each arm between the elbow and the shoulder, and one on each side of the body just above the belt line. Each S responded with one of two response alphabets during 11 sessions of 41 trials each, over a period of three days. Differences between the two response alphabets were not significant, and neither were differences attributable to the interaction of the response alphabets with the number of loci stimulated. Increases in the percentages of erroneous responses with increases in the number of loci stimulated were both large and statistically significant; these increases were interpreted as evidence of a central mechanism of cutaneous masking.