Douglas P. Ferraro

Teacher Mentoring and Teacher Retention

Four years after their initial, mentored teaching year, two cohorts of beginning teachers (N= 160) were surveyed to determine whether they had remained in teaching and their retrospective attitudes about mentoring. Approximately 96% of those located were still teaching. Of the different types of support they received from their mentors, they most valued emotional support. It is suggested that teacher mentoring may reduce the early attrition of beginning teachers.

Lack of Tolerance to Δ9-Tetrahydrocannabinol in Chimpanzees

Five chimpanzees were given Δ9-tetrahydrocannabinol (Δ9THC): 1.0 milligram per kilogram of body weight for 21 days and 4.0 milligrams per kilogram of body weight for 42 days. Although accuracy and speed of performance on a delayed matching-to-sample task were significantly affected by both doses, tolerance to Δ9THC did not develop. No long-term behavioral effects of Δ9THC were observed after termination of the drug regimens.

Effects of marihuana extract on the operant behavior of chimpanzees

Six chimpanzees were trained to panel push under a food reinforcement baseline in which three operant schedules, each associated with a different stimulus, were presented successively. The fixed ratio (FR) reinforcement schedule required the emission of 40 responses for reinforcement. Reinforcement under the differential reinforcement of low rate (DRL) schedule was delivered only when successive responses were spaced by at least 10 sec. During the extinction or time out from positive reinforcement schedule (TO), no responses were reinforced. In Experiment 1, amounts of marihuana extract containing from 0.2 to 4.0 mg/kg (−)-Δ9-trans-tetrahydrocannabinol (Δ9-THC) were orally administered 1 h prior to experimentation. In Experiment 2, 1.0 mg/kg Δ9-THC was orally administered between 1 and 23 h prior to experimental sessions. No disruption of stimulus control or drug effects during TO were observed. Both DRL and FR response suppression occurred at the highest drug dose. Lower Δ9-THC doses produced facilitation of DRL responding up to 12 h following drug administration. Although FR responding was less sensitive, Δ9-THC stimulated FR behavior from 2 to 5 h following drug administration. It was concluded that marihuana has a biphasic effect on food reinforcement schedule controlled operant behavior.

Tolerance to the behavioral effects of marihuana in chimpanzees

Abstract Two experiments were conducted in which adult chimpanzees were first trained to respond under time-based reinforcement schedules that required a temporal spacing of successive responses. The chimpanzees were then given 14 consecutive daily doses of either a totally synthetic Δ 9 - trans -tetrahydrocannabinol ( Δ 9 -THC) or a marihuana extract containing a known amount of Δ 9 -THC. In Experiment 1 the drug dose was increased from 1 mg/kg to 4 mg/kg Δ 9 -THC. The amount of drug repeatedly administered in Experiment 2 was 3 mg/kg Δ 9 -THC. In both experiments the first administration of Δ 9 -THC produced a significant behavioral change from nondrug control responding which was followed in subsequent sessions by the rapid development of tolerance. That is, the behavioral effects intially produced by Δ 9 -THC progressively decreased with repeated drug administrations. Consistent but temporary departures from control responding occurred during postdrug sessions. The possibility that the development of tolerance to marihuana may be, in part, due to the learning of responses which compensate for marihuana-produced behavioral effects was discussed.

Effects of Oral Δ9-Tetrahydrocannabinol on Operant Reinforcement Schedule Performance in Rats

Eight rats were trained to barpress for water reinforcement under a variable interval 60-sec operant schedule. Nine acute oral administrations of (–)Δ9- trans -tetrahydroca

Biphasic effects of 9 -tetrahydrocannabinol on variable interval schedule performance in rats.

Four rats were trained to barpress for water reinforcement under a variable interval 60 sec schedule. Nine acute administrations of (−)δ9-trans-tetrahydrocannabinol, in amounts ranging from 0.25 to 16.0 mg/kg, produced dose-related effects on responding; overall response rate increased at lower doses, while higher doses produced ataxia and a complete suppression of responding. Increased response rates reflected changes both in response spacing and in the lengths of post-reinforcement pauses. It was concluded that marihuana has a biphasic effect on variable interval water-reinforced behavior in rats.

Variability of Response Location during Regular and Partial Reinforcement

4 pigeons were trained to peck an 8-location response strip for grain reinforcement and given 14-session exposures to variable interval and regular reinforcement schedules. Regardless of the sequence of reinforcement schedules, partial reinforcemen produced greater response-location variability along the topographical response continuum than did regular reinforcement.

Effects of chronic exposure to Δ9-tetrahydrocannabinol on delayed matching-to-sample in chimpanzees

Three groups of four chimpanzees were trained on a 20-sec delayed matching-to-sample task and then were exposed to a 152 day chronic drug regimen. Two of the chimpanzees in each group were drug naive. The other two chimpanzees in each group had experienced 45 doses of Δ9-tetrahydrocannabinol (Δ9-THC) four months prior to the present experiment. One group of animals served as nondrug controls. A second control group received an oral dose of 1.0 mg Δ9-THC per kilogram of body weight following each matching-to-sample session. The experimental group was given the same dose of Δ9-THC prior to each daily session. The initial administrations of the drug before but not after each session produced a significant decrease in matching-to-sample accuracy. During the course of the chronic drug regimen, animals in the experimental group recovered very slowly from this initial impairment in matching-to-sample performance. The extent to which the experimental animals recovered seemed to depend upon their pre-experimental drug histories. The drug-experienced animals developed complete tolerance within five weeks while the previously drug-naive animals did not so do even after five months exposure to the drug. However, no residual or long-term effects were observed following termination of the chronic drug regimen.

Behavioral Effects of Small Oral Doses of Marihuana Extract in Chimpanzees

Four chimpanzees were trained to respond on three operant schedules of positive reinforcement. Amounts of a marihuana extract containing from 200 to 800 µg/kg (–)-Δ9-trans-tetrahydrocannabi

Comparison of behavioral effects of synthetic (?)?9-trans-tetrahydrocannabinol and marihuana extract distillate in chimpanzees

Eight chimpanzees emitted panel push responses under a procedure in which three operant schedules of positive reinforcement, each associated with a different stimulus, were presented successively. The fixed ratio (FR) schedule required the emission of 40 responses for reinforcement. Reinforcement under the differential reinforcement of low rate (DRL) schedule was delivered only for a response that followed the immediately preceding response by 10 or more sec. No responses were reinforced under the extinction or time out from reinforcement (TO) schedule. The behavioral effects produced by a marihuana extract distillate containing a known amount of (−)δ9-trans-tetrahydrocannabinol (δ9-THC) were compared with those produced by a totally synthesized δ9-THC. On four separate drug days each chimpanzee was orally administered one of the two compounds 2.5 h prior to experimentation in amounts yielding 1.0 mg/kg δ9-THC. Only the DRL schedule performance was significantly affected by either drug compound. Both the marihuana extract and the synthetic δ9-THC produced a statistically significant decrease in the percentage of correct DRL responses. However, no statistically significant differences between the drug effects produced by the two δ9-THC dose forms were obtained.