Partial integration of single electrocutaneous pulses

Psychometric functions generated by single eleetroeutaneous stimuli yielded a median coefficient of variation ( σ/μ ) of 0.23. These data are consistent with other psychometric data recently reported by us which yielded σ/μ ratios of this size. The data are discussed and related to conflicting data reported in the recent literature indicating coefficients of variation for this mode of stimulation which are only 1/3 as large. Evidence is presented for partial temporal summation (time-intensity reciprocity) for electrocutaneous stimuli ranging from 175 to 610 microseconds. The data are best fitted by the equation I x t^a = k, where a is approximately 0.57. This equation and exponent also fit summation data reported by the same authors who report finding steep psychometric functions. Clearly, then, the mechanism responsible for the very limited temporal summation found for eleetrocutaneous stimulation and the mechanism responsible for very steep psychometric functions are not identical. The discussion also includes speculation regarding possible mechanisms and suggestions for research.