Force Differentiation in Human Subjects: Effects of Criterion Range and Level

Abstract

Four human subjects were provided with a cue-light stimulus as the nominal reinforcer for correct responses in a procedure involving the differential reinforcement of the peak force of a finger-press response. Force bands with 10, 20, 40, and 80 gm. widths above 120-gm. and a 240-gm. lower limit were the systematically manipulated criteria for reinforcement. Peak-force distributions showed a decrease in mean peak force and a decrease in the percent of in-band responses as the upper limit of the band was lowered. Response variability was less regularly affected but suggested some tendency toward reduction with band-width reduction. Equivalent band widths at 120- and 240-gm. levels produced considerably less variability and greater in-band frequencies at the lower level. A tendency interpreted as energy conservation was manifested by more frequent below than above-band errors and force-distribution medians below the midpoint of the reinforced range.