Baron, A., & Herpolsheimer, L. R. (1999). Averaging effects in the study of fixed-ratio response patterns. Journal of the Experimental Analysis of Behavior, 71, 145-153.

Three rats were exposed to multiple fixed-ratio schedules in which large and small ratios alternated in an irregular order. Over a series of training phases, one ratio was held constant as the second ratio was increased to higher values. On average, postreinforcement pauses increased in duration as the ratio size was increased. Pausing was controlled by the size of the upcoming ratio; the previous ratio had smaller and less consistent effects. However, more detailed consideration of the aggregated data indicated that the pause distributions were positively skewed and that changes in average performances were more a consequence of increased skew rather than shifts of the entire distributions. Moreover, the distributions of pauses from condition to condition overlapped, and brief pauses were common even at the highest ratios. These results demonstrated that depictions of pausing based on aggregated data can be misleading without corresponding information about variations in the distribution on which the averages are based.

Key words: fixed-ratio schedules, postreinforcement pause, averaging, molar versus molecular analysis, lever press, rats