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Four experiments studied contextual control over rats' freezing to conditioned stimuli (CSs) that had been paired with shock and were then extinguished. In Experiment 1, rats were exposed to a CS A-shock and a CS B-shock pairing in Context C. CS A was then extinguished in Context A, and CS B in Context B. Freezing was renewed when each CS was presented in(More)
Rats acquired a preference for an aqueous odor (almond) presented in simultaneous compound with sucrose. Separate presentations of saccharin reduced this preference in rats with ad-lib access to food during training or at test, but not in rats that were hungry during both training and test. In contrast, separate presentations of sucrose reduced the(More)
The Systolic Hypertension in the Elderly Program (SHEP) staff contacted 447,921 screenees, of whom 11,919 (2.7%) were originally eligible and 4,736 (1.1%) maintained eligibility and were randomized. The total number of participants enrolled at the 16 clinical centers ranged from 133 to 559. The low yield of screenees to randomizations resulted from the(More)
We used 1-, 2-, and 3-context designs to study the control exerted by contexts over freezing in rats exposed to a conditioned stimulus (CS) in advance of its pairing with a shock unconditioned stimulus. The latent inhibition observed when preexposure, conditioning, and testing occurred in the same context was attenuated if preexposure occurred in a(More)
Several recent studies with rats (Sprague-Dawley strain) have documented that an odor previously paired with shock potentiates the acoustic startle response, a phenomenon referred to as conditioned odor potentiation of startle (OPS). A surprising finding in these studies was that OPS did not extinguish even though the odor was present throughout the 25-min(More)
During the recruitment phase of a trial it is often found that recruitment is not proceeding as quickly as projected. Budget limitations require innovative methods, such as use of volunteers, to increase recruitment yields without increasing cost. In the Systolic Hypertension in the Elderly Program (SHEP), volunteer staff at 12 of the 16 clinical centers(More)
A series of experiments studied reacquisition of fear reactions to a completely extinguished context. Reacquisition was rapid when reconditioning occurred as soon as the fear reactions were completely extinguished, showing that the original conditioning was intact. However, when reconditioning occurred after massive extinction training, fear reactions were(More)
Rats in a state of salt need prefer a flavor that has previously been paired with saline (Experiment 1). In Experiments 2 and 3, rats exposed to 2 saline concentrations, presented either concurrently or on separate trials, and each paired with a different flavor, showed a preference for the flavor that had been associated with the stronger saline. This(More)