ABSTRACT
Conditional discriminative choice tasks can be arranged such that all correct choices yield the same reinforcer or such that each type of correct choice has its own unique reinforcer. The former is the traditional "Common Outcomes" Procedure; the latter is the "Differential Outcomes" Procedure. Use of this Differential Outcomes Procedure facilitates the rate of learning, increases the asymptotic level of performance, and enhances working-memory based performances in both animals and humans. These facts have stimulated many questions and experiments about learning and memory mechanisms and fostered potential applications.
Subject(s)
Choice Behavior/physiology , Animals , Avoidance Learning/physiology , Cues , Discrimination Learning/physiology , Discrimination, Psychological/physiology , HumansABSTRACT
The interaction of food-based memories and food-event outcome expectancies in pigeons was assessed using a simultaneous, delayed-symbolic-matching-to-sample procedure. The components of the compound sample were presented in sequence, and consisted of a food-based event (food or no-food) followed by a color cue (red or green). Choice of a pattern of horizontal lines was "correct" following presentation of the red cue, while choice of a vertical line pattern was "correct" after green. In all but a control condition, the food-based event with which a trial began, or the food-event outcome with which a trial concluded, or both, were also correlated with the correct pattern. Of particular interest was the relative accuracy of two groups for whom both memories and expectancies were correlated with the correct choice-pattern. For one group, the memories and expectancies corresponding to the pre- and postchoice food-related events were similar, whereas for the other they were dissimilar. Outcome expectancies supported a higher level of performance than food-based memories, and subjects with both outcome expectancies and food-based memories chose more accurately than those with memories or expectancies only. In addition, subjects with dissimilar food-based memories and outcome expectancies chose more accurately than those with similar memories and expectancies. The implications of the above findings for the nature of event representation in pigeons are discussed.
Subject(s)
Choice Behavior , Conditioning, Operant , Memory , Mental Recall , Set, Psychology , Animals , Color Perception , Columbidae , Cues , Discrimination Learning , Pattern Recognition, VisualABSTRACT
Controllability and predictability are important modulators of the behavioral effects of aversive stimulation on animals. An experiment was conducted to further investigate both the immediate and proactive effects of controllability and predictability of shocks on adrenocortical responsivity. In an initial stress induction phase, the controllability and predictability of electric shocks were independently varied in groups of dogs, and plasma cortisol responses were measured. In a subsequent test phase, all groups of dogs received identical shocks in a novel situation. Cortisol responses to these test shocks were analyzed as a function of the controllability and predictability of previous induction shocks. The results showed that during stress induction, uncontrollable shocks produced significantly greater cortisol elevations that controllable shocks but that predictability had no significant effect on cortisol responses. However, unpredictable shocks during stress induction acted proactively to significantly increase cortisol response to novel test shocks, whereas prior controllability did not modulate subsequent responsivity to novel shocks.
