Journal of experimental psychology. Animal behavior processes
-
J Exp Psychol Anim Behav Process · Jul 1986
Interaction of Pavlovian conditioning with a zero operant contingency: chronic exposure to signaled inescapable shock maintains learned helplessness effects.
In four experiments we used triads, consisting of escapable-shock (ES), yoked inescapable-shock (IS), and no-shock (NS) rats, to investigate the effect of the interaction between Pavlovian contingencies and a zero operant contingency (i.e., uncontrollability) upon subsequent shock-escape acquisition in the shuttle box. After exposure to 50 signals and shocks per session for nine sessions, interference with shuttle box escape acquisition for IS rats was a monotonically increasing function of the percentage of signal-shock pairings during training (Experiment 1), with 50% pairings producing little or no impairment. Without regard to signaling, ES rats performed as well as NS rats. ⋯ The continuous presence of the signal during the test contrasted with its discrete (5-s) presentation during training and suggested that an antagonistic physiological reaction rather than a specific competing motor response had been conditioned. Experiment 4 provided evidence for possible conditioned opioid mediation by demonstrating contemporaneous stress-induced analgesia and shock-escape impairment in IS rats chronically exposed to 100%, but not to 50%, signal-shock pairings, and the elimination of both analgesia and escape interference by the opiate antagonist naltrexone. Thus, chronic exposure to uncontrollable shocks appears to maintain the impairment produced by acute exposure only if the shocks are adequately signaled.
-
Three experiments with rat subjects assessed conditioned analgesia in a Pavlovian second-order conditioning procedure by using inhibition of responding to thermal stimulation as an index of pain sensitivity. In Experiment 1, rats receiving second-order conditioning showed longer response latencies during a test of pain sensitivity in the presence of the second-order conditioned stimulus (CS) than rats receiving appropriate control procedures. ⋯ Rats receiving paired morphine-shock presentations showed significantly shorter response latencies during a hot-plate test of pain sensitivity in the presence of the second-order CS than did groups of rats receiving various control procedures; second-order analgesia was attenuated. These data extend the associative account of conditioned analgesia to second-order conditioning situations and are discussed in terms of the mediation of both first- and second-order analgesia by an association between the CS and a representation or expectancy of the US, which may directly activate endogenous pain inhibition systems.
-
J Exp Psychol Anim Behav Process · Jan 1982
Eye movements of monkeys during discrimination learning: role of visual scanning.
Four experiments were conducted on stumptailed monkeys (Macaca arctoides) to determine whether the high levels of visual scanning (shifts in fixation from one discriminative stimulus to the other) seen during discrimination learning play a necessary role in this learning. In Experiments 1 and 2, the monkeys were given a series of two-choice, dot-pattern discrimination reversal problems. Normal visual scanning before a choice response was allowed during all but the reversal trials of half of the problems. ⋯ Experiment 4 was similar to the preceding experiment except that, under the experimental condition, each trial began with the uninformative stimuli, which were replaced by the discriminative stimuli when visual scanning occurred. The uninformative stimuli had no clear-cut effect on discrimination learning in this experiment. These experiments indicate that the information provided by above-minimum levels of scanning is not necessary for discrimination learning per se, but it dose appear necessary for efficient discrimination learning.
-
J Exp Psychol Anim Behav Process · Jul 1980
Oddity learning in the pigeon as a function of the number of incorrect alternatives.
Pigeons' rate of learning a two-color oddity task increased as a function of the number of incorrect alternatives from 2 to 24 in Experiments 1, 2, and 3. In general, pigeons that were transferred from many-incorrect-alternative to two-incorrect-alternative oddity performed better than controls, but considerably below baseline (Experiments 2 and 3). ⋯ In Experiment 6, pigeons exposed to a nine-stimulus array in which the odd stimulus appeared (a) in the center or (b) separate from the array learned faster than when the odd stimulus was at the edge. This outcome suggests ththe figure-ground relation between the odd stimulus and the incorrect alternatives plays a role in the facilitation produced by increasing the number of incorrect alternatives but that poor performance on the standard, three-alternative oddity task appears to be due to center-odd trials which provide a difficult size or number discrimination.
-
J Exp Psychol Anim Behav Process · Oct 1979
Role of conditioned contextual stimuli in reinstatement of extinguished fear.
If the unconditioned stimulus (US) is presented independently of the conditioned stimulus (CS) following extinction, the conditioned response may be reinstated to the CS. Three experiments are reported that suggest that reinstatement is mediated by conditioning to contextual stimuli that are present during both US presentation and testing. Shocks presented to rats following the extinction of conditioned suppression reliably reinstated suppression to the CS, but only when they were presented in the context in which testing was later to occur. ⋯ Moreover, fear of the context was never detected directly by depressed bar-press rates in the absence of the CS. The results do not support the hypothesis that reinstatement results from an increment in the strength of a memory of the US that has been weakened during extinction. Problems inherent in controlling and detecting levels of context conditioning that may influence behavior toward nominal CSs are discussed.