Etcetera

Publishers interested in having their materials reviewed here are requested to send two copies to Dr. Daniel Sinick, George Washington University, Washington, D.C. 20006. Items reviewed in this column are not available from APGA.     

Polydipsia induced in the rat by a second-order schedule

Drinking was studied in rats pressing a bar on a second-order schedule in which every third completion of a 1-min fixed interval was followed by food presentation. A brief flash of light signaled the completion of each fixed-interval component. The rats drank not only after the food presentations but also after presentations of the light flash alone. A high rate of steady drinking followed intervals terminated by a food presentation. Drinking that followed intervals terminated by a light flash alone was of comparable rate, but characteristically interrupted by bar pressing. When 250-mg food pellets were used instead of 45-mg pellets, both drinking and bar-pressing rates increased substantially.     

Etcetera

Publishers interested in having their materials reviewed here are requested to send two copies to Dr. Daniel Sinick, George Washington University, Washington, D.C. 20006. Items reviewed in this column are not available from APGA.     

Frequency-selective detection at three signal amplitudes

Using the probe-signal method, frequency-response characteristics were obtained for four Os detecting signals nominally of only 1000Hz under three signal-amplitude conditions: E/N_o=10.0, 12.6, and 15.8. Detection of 1000-Hz signals decreased systematically with signal-amplitude decreases, but signals at 850 Hz and at 1150 Hz were detected at or near the chance level during all signal-amplitude conditions. From the detection performance data, the detectability was inferred for four probe-signal frequencies relative to that of 1000-Hz signals for each of the amplitude conditions. From the curvesofrelative detectability, hal[-detectability bandwidths were estimated. Neither the relative detectability curves nor the half-detectability bandwidths indicate any systematic change in the frequencyselectivebehavior of the auditory O across the signal amplitudes used.