Pentobarbital was injected into rats 20 min after they were placed in an apparatus where heart rates were recorded. Amphetamine was injected after they were removed from the apparatus 29-30 min later. A Pavlovian conditioned response (CR) began after three or four such trials in the form of a failure of conditioned rats to show the same decline in heart rate obtained in controls after the pentobarbital injection. On later trials, the amphetamine was not injected until 50 min after the pentobarbital, and the CR was most obvious during the period 30-50 min after the pentobarbital injection, an effect characteristic of Pavlovian delay conditioning. The pharmacological effects of pentobarbital were necessary for conditioning because the CR was not obtained (a) when normal saline was substituted for the pentobarbital after successful conditioning or (b) when saline was used instead of pentobarbital throughout. Because of the speed and effectiveness of the conditioning, we believe the mechanism responsible for it has homeostatic regulation as its natural role. It was puzzling that environmental cues seemed to have a role in the conditioned stimulus complex, because conditioning was not apparent when the drug-drug pairings were administered in the home cage.

Interactive modeling is frequently used in teaching skills to children with developmental delay. This study compared the performance of 12 children (7 males, 5 females; 4–10 years of age) each trained in two tasks, one through interactive modeling (with or without verbal reinforcement) and the other through passive observation. Results showed that passive modeling produced better rated performance than interactive modeling and that verbal reinforcement was counterproductive. These findings suggest that current instructional strategies may need to be reconsidered for children with developmental delay.

No abstract

Octopus vulgaris is able to open transparent glass jars closed with plastic plugs and containing live crabs. The decrease in performance times for removing the plug and seizing the prey with increasing experience of the task has been taken to indicate learning. However, octopuses' attack behaviors are typically slow and variable in novel environmental situations. In this study the role of preexposure to selected features of the problem-solving context was investigated. Although octopuses failed to benefit from greater familiarity with the training context or with selected elements of the task of solving the jar problem, the methodological strategies used are instructive in potentially clarifying the role of complex problem-solving behaviors in this species including stimulus preexposure and social learning.