Fig 13.

Results from an experiment showing discrimination of correlation. Four cumulative records of complete sessions from 4 pigeons are shown. At the beginning of the session, the correlation between pecking and feeding is positive; if a peck occurred anywhere in the scheduled time interval, food was delivered at the end of the interval. Following the first vertical line, the correlation switched to negative; a peck during the interval canceled food at the end of the interval. Peck rate fell. Following the second vertical line, the correlation reverted to positive, and peck rate rose again. Adapted from Baum (1981a).