37. The data set shown above is from the article Compounding of Discriminative Stimuli from the Same and Different Sensory Modalities (J. Experiment.

Anal. Behav., 1971: 337—342). Rat response was maintained by xed interval schedules of reinforcement in the presence of a tone or two separate lights.

The lights were of either moderate (L1) or low (L2)

intensity. Observations are given as the mean number of responses emitted by each subject during single and compound stimuli presentations over a 4-day period. Carry out an appropriate analysis.