Rate-change effects with equal potential reinforcements during the “warning” stimulus

Two pre-schedule-change stimuli were superimposed on the same VI baseline and were thereby equated with respect to reinforcement potential. One such stimulus preceded a transition to an extinction schedule or a VI schedule of lower reinforcement frequency while the other preceded a transition to a VI schedule of higher reinforcement frequency. It was found that response rate during the warning stimulus was greater preceding the transition to the lower reinforcement frequency than it was preceding the transition to the higher reinforcement frequency. That difference was often evidenced by an absolute increase and decrease in rate, in conformity with previous findings on the topic. The present experiment extends previous findings in several ways, including the presentation of quantitative estimates of the effects

Changeover delay and concurrent schedules: some effects on relative performance measures

The pigeon and the rat partition total response output between both schedules of a concurrent variable-interval pair. The quantitative nature of a partition seems critically dependent on the relative rates with which the two schedules provide reinforcements for responding, in addition to the changeover delay. The manner in which the changeover delay controls the partition was studied by varying the duration of the changeover delay from 0 to 20 sec with each of two pairs of concurrent variable-interval schedules, viz., Conc VI 1.5-min VI 1.5-min and Conc VI 1-min VI 3-min. Rats served as the subjects and brain stimulation was employed as the reinforcer. When the schedules were Conc VI 1.5-min VI 1.5-min, relative response rate approximated 0.50 at all values of the changeover delay. When the schedules were Conc VI 1-min VI 3-min, relative response rate, computed with respect to the VI 1-min schedule, increased when the duration of the changeover delay increased. Changeover rate decreased when the duration of the changeover delay increased. The decrease was the same for both VI schedules of the Conc VI 1.5-min VI 1.5-min pair but was more rapid for the VI 3-min schedule of the Conc VI 1-min VI 3-min pair

Undermatching and overmatching: The fixed-ratio changeover requirement

Concurrent variable-interval two-minute and six-minute schedules were arranged while the fixed-ratio changeover requirement was varied among one, two, and four responses. A four-response requirement produced overmatching in the response and time data. A one-response requirement produced consistent undermatching in the time data but mixed results in the response data. The two-response requirement showed undermatching in the time data and overmatching in the response data. The results are discussed in relation to previous research using changeover requirements of five and ten responses, which produced clear tendencies toward overmatching, especially with response data. Taken together, these findings suggest that matching is not a unique result, and that undermatching or overmatching can be produced by continuous variation of the changeover requirements

Antecedents to Fechner's law: the astronomers J. Herschel, W. R. Dawes, and N. R. Pogson

The history of the stellar magnitude scale is briefly traced from the second century b.c. until the middle of the nineteenth century. It becomes clear that astronomers formulated “Fechner's Law” by about 1850. While Fechner is credited with the grander view of things, the contention is made that the astronomers John Herschel, W. R. Dawes, and N. R. Pogson have not been given their due by historians of psychology