2 experiments concerned adaptation to a water deprivation schedule. Guinea pigs needed about 21 days to adjust to such a schedule, and a green supplement which is necessary for maintaining health does not interfere markedly with water consumption.
Two groups were tested for spontaneous alternation using massed and spaced trials but alternation rate was not above chance level. Two experiments then examined the use of visual stimuli as pacers for an approach response. The results indicate that subjects responded to complexity and that complexity may be a more effective pacer than novelty.
Arterial pulse transit time (PTT) and ECG•initiated transit time (ECG•TT) can be measured noninvasively in human subjects and reflect significant aspects of cardiovascular activity. In eight conditioning trials, with the cold pressor as the unconditioned stimulus, conditioned decreases in PTT and increases in ECG•TT were observed in later trials, concomitant with con• ditioned vasoconstriction. The results are discussed in terms of the potential contribution of PTT and ECG•TT in examining the effects of psychological processes on the cardiovascular system. Classically conditioned cardiovascular responses have been widely investigated in animals (e.g.,
Two experiments in a free-operant situation tested the generality of Lawrence & Festinger's (1962) hypothesis that the total number of nonreinforced trials, not percentage of reward, is the critical variable in determining resistance to extinction. This was supported by Experiment 1. However, when rate of responding was held constant in Experiment 2 the hypothesis was not supported. The results suggest that S's with faster rates of responding in acquisition make more responses in extinction indicating an energizing effect of nonreinforcement. Lawrence & Festinger (1962) have hypothesized that the partial reinforcement effect (PRE) may be understood in terms of a theory of cognitive dissonance. ACCOrding to the hypothesis, dissonance occurs on each unrewarded trial but S learns to reduce this dissonance by finding "extra attractions" in the situation and so continues to perform the response in the absence of the normal reward. A corollary of this hypothesis is that it is the total number of unrewarded trials that determines resistance to extinction, and not, as commonly assumed, percentage of reward. In support of this Lawrence and Festinger report an experiment in which three levels of unrewarded trials and three percentages of reward were combined in a 3 by 3 factorial design. The apparatus was an S-shaped rwlway conta,ining obstructions. Results showed that the only significant effect was number of unrewarded trials. Since recent theorizing on the PRE suggests that discrete trial and free responding situations may not yield comparable data (Amsel, Rashotte, & Mac-Kinnon, 1966), it would seem profitable to test the generality of Lawrence and Festinger's finding by attempting to replicate the results in a standard free operant situation. EXPERIMENT 1 Subjects Ss were 44 experimentally naive male albino rats of the Wi star strain with ages ranging from 155 to 175 days at the commencement of the experiment. Procedure Apparatus consisted of three Skinner boxes each equipped with a bar requiring a force of 15 g to depress. The reinforcing mechanism was a modified Deutsch Spaghetti Gun (Trotter, 1956) which dispensed pieces of commercial spaghetti with a mean weight of 20 mg. Three weeks before the beginning of the experiment Ss were deprived of food for 48 h and thereafter
2 groups of chicks were trained to run to one end of an apparatus which consisted of a single runway with a central start box and goal box at each end. Ss receiving partial reinforcement during acquisition learned to reverse this response more rapidly than Ss given continuous reinforcement.
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