A new principle of pellet feeder design

Most current commercial devices dispense dry food pellets by moving the pellets horizontally toward a discharge point. Individual pellets, captured by perforations in a horizontal metal disk, are discharged one by one by stepwise rotation of the disk within the pellet reservoir. In our laboratory, where the average pellet discharge rate is some 20,000 pellets per week, feeders of this type produced occasional problems. Some were electronic; others involved failure always to capture a pellet in each perforation, particularly when the pellet supply was low. But the most common problem was an accumulation of pellet chips and dust under and around the perforated disk, which ultimately jammed the mechanism. Despite weekly cleaning and maintenance, troubles arose at least twice a month, prompting a search for a simpler pellet-feeder design which would be more reliable and require less maintenance. The present pellet feeder employs a vertical rather than horizontal design principle. It has been used extensively in operant conditioning applications for more than a year. More than 200,000 pellets have been reliably discharged from a single feeder without a breakdown. No maintenance, other than a weekly cleaning of the discharge tube, has been required.     

Schedules using noxious stimuli. II: low intensity electric shock as a discriminative stimulus

The presence or absence of pulses of low intensity electric shock was used as a discriminative stimulus to control responding under fixed ratio reinforcement in the squirrel monkey. Initially brief periods of nonreinforcement were lengthened only when discriminative control was evident. Discriminative control was studied by (1) varying the duration of nonreinforcement periods; (2) reversing the stimulus conditions correlated with reinforcement and nonreinforcement periods; and (3) determining the minimum shock intensity necessary to maintain discriminative control. Stimulus control was not reliably affected by d-amphetamine, chlorpromazine, or morphine. The discriminative control by pulses of low intensity electric shock was similar to that by other discriminative stimuli, except that the control developed slowly and was better when the pulsing shock was correlated with reinforcement than when correlated with nonreinforcement.     

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.     

Drug effects in squirrel monkeys trained on a multiple schedule with a punishment contingency

The behavior of four monkeys trained on a multiple schedule was differentially sensitive to selected pharmacological agents. The three components of the multiple schedule were: (1) a variable-interval schedule in which responses were reinforced on the average of once per minute; (2) a concurrent schedule in which every tenth response was reinforced and every fifteenth response, on the average, was shocked; and, (3) a neutral stimulus in the presence of which responses were neither reinforced nor shocked. Pentobarbital, chlordiazepoxide, and meprobamate increased responding during each of the components. Scopolamine and d-amphetamine decreased variable-interval performance, had minimal effects on performance during the concurrent-schedule component, and increased responding in the presence of the neutral stimulus. Chlorpromazine decreased variable-interval responding and had slight effects on the responding during the other two components.     

Intake and Walk-in Procedures in a College Counseling Setting

Modifications of the intake procedure usually employed in counseling settings were adopted in order to provide students the opportunity for immediate contact with a counselor. Elimination of the waiting list, reduction in number of missed appointments, and reduction of length of counseling came about. Staff satisfaction with the new approach has been high and there would be opposition to reverting to the scheduled initial interview. Possible changes in the type of problem or clients' readiness for problem-solving were observed.     

Effects of an Accelerated Reading Course on SAT-V Scores

3 groups of university freshmen took the SAT-V before and after a course in Accelerated Reading. The mean post-test scores for 2 groups increased slightly less than 10 points, while the mean post-test score for the third group decreased significantly. It is concluded that for the type of students used in this study, a course emphasizing speed and accuracy of reading is not of value in increasing scores on the verbal part of the Scholastic Aptitude Test.