PUNISHMENT BY SD ASSOCIATED WITH FIXED-RATIO REINFORCEMENT.

Two pigeons were trained with positive reinforcement on a multiple FR VI 2 schedule. The VI 2 component was held constant while the FR component was changed from ratios of 1 to 300. After responding had stabilized at each FR value, VI responses produced briefly either the fixed-ratio S(D) or a stimulus uncorrelated with either schedule component. Compared to the effects of the uncorrelated stimulus change, the fixed-ratio S(D) produced a decrease in VI responding proportional to the size of the FR requirement. It is concluded that stimuli associated with high FR schedules served as punishment for the ongoing behavior.