Augmentation of eating following a signal for feeding in rats

Previous studies have shown that a CS for feeding produces increases in some measures of excitation, but effects on other behaviors have not been examined. Two experiments examined effects on eating. In each experiment, one group of rats was presented with a CS preceding feeding, while control groups had no anticipatory signal. Ss with signaled feeding learned to eat more than control Ss, and their body weights were relatively higher. These results indicate that conditioned incentive stimuli may have broader effects than have classically been attributed to them. It is also suggested that learned factors may mediate the effects of deprivation operations on eating and play a significant part in the regulation of feeding.     

Effect of shifts in body weight on rats' straight alley performance as a function of reward magnitude

The performance of rats trained in a straight alley for 55 trials under 75% body weight and then shifted to 90% body weight was compared to that of rats trained only under 90% body weight. When training was with a small reward the speed of the shifted group decreased to the level of the 90% small reward control groups, but when training was with a large reward the speed of the shifted group dropped below the level of the 90% large reward control group. Thus, the effects on performance of shifting deprivation level following extended training depend on the reward magnitude employed.     

The CS-US interval function in rabbit nictitating membrane response conditioning: Single vs multiple trials per conditioning session

The effect of varying trials per day conditions on the CS-US interval or interstimulus interval (ISI) function in rabbit nictitating membrane response conditioning was studied in two experiments. Experiment 1 showed that a 1250-msec ISI was more effective than a 250-msec ISI when there was 1 trial/day. Experiment 2 showed that as the number of trials per day decreased from 20 to 1, the superiority of the 250-msec ISI group over the 1250-msec ISI group declined, with a reversal at 1 trial/day. Results are interpreted in terms of the role of a hypothesized CS-elicited short-duration orienting response in CR performance.     

Effects of sucrose concentrations on single alternation runway responding in rats

Rats received runway training under alternating reward and nonreward in which rewarded (R) trials provided 32 or 4% sucrose concentration from a drinking tube and nonrewarded (N) trials provided a dry tube or, for half of the rats in the 32% condition, plain water. Both 32 and 4% concentrations yielded faster running on R trials than on N trials; but this effect was reliable only for the 32% condition. Compared to 4% sucrose, 32% sucrose yielded reliably slower running on N trials and unreliably faster running on R trials.     

Delayed reward learning: Disproof of the traditional theory

Without the aid of secondary rewards to bridge the temporal gap, each of 15 rats learned to select the rewarded side of a T-maze although the reward was delayed until 1 min after the response was emitted. Similar results were obtained from another group of eight rats for which the length of the delay was 5 min. In a final experiment using the same basic procedure, five groups of rats were trained for 25 days with delays of 0.5, 1.0, 2.0, 4.0, or 8.0 min. The percentage of correct responses did not significantly differ among groups. According to prevailing psychological theory, these results are impossible.     

Control of avoidance by a response-produced stimulus

Three pigeons were trained to press a foot pedal to postpone electric shock. The safety signal was a tone of 1000 Hz, which sounded for 5 sec following each press; silence therefore served as a warning signal. After the performance approached asymptote, test sessions were interspersed among the training sessions. Following a warm up, the shock was omitted (extinction), and no tone or a tone of 250, 500, 1000, 2000, or 4000 Hz was presented following each press for the remainder of the session. Gradients of generalization plotted in terms of the number of times the tone was produced on each test peaked at 1000 Hz, indicating that the performance was controlled by the frequency. Since this dimension is orthogonal to absence of tone, the gradient cannot be attributed to differences in the magnitude of change in the warning signal. It was concluded that response-produced stimuli reinforce avoidance behavior.     

Infantile stimulation and its effects on frustration- and fear-motivated behavior in rats

Infant rats that were either removed from the nest each day (handled) or left undisturbed (nonhandled) were, in adulthood, given 72 food-reinforced runway acquisition trials followed by 24 trials of extinction training with or without shock. Handled and nonhandled control animals were given runway training without food reinforcement. Reinforced rats ran faster than nonreinforced rats, and handled rats ran faster than nonhandled rats during the initial trials of runway acquisition irrespective of the reinforcement condition. Nonhadled rats stopped running sooner than handled rats when shock was introduced in the goalbox, but differences between handled and nonhandled rats given extinction training without shock were small. Results of a second experiment showed no differences between handled and non-handled rats in the magnitude of the depression effect after an incentive shift. It was concluded that infantile handling had little effect on frustration-motivated behavior, but did affect fear-motivated behavior.     

Evaluation,self-awareness,and task performance

Two contradictory hypotheses regarding the effect of self-attention or self-awareness on task performance are considered. Recent research on test anxiety indicates that self-awareness interferes with task performance by decreasing the proportion of attention paid to the task. Wicklund and Duval's (1971) theory of objective self-awareness predicts the opposite: that self-awareness will induce a person to try harder and to perform at a higher level. Experimental evidence indicates that both hypotheses are correct, each at a different level of evaluation. The results are discussed in terms of their implications for a unified social-psychological theory of evaluative self-awareness which could account for findings now classed under separate headings such as test anxiety, self-awareness, and social facilitation.     

Training cooperation in the Prisoner's Dilemma

Female Ss' choices in two types of mixed-motive game situations were used to select Ss who had predominantly Own Gain and Ss who had predominantly Relative Gain goals. On the basis of simple reward notions, it was predicted that the former but not the latter would change from competitive to cooperative responding in decomposed Prisoner's Dilemma game situations when interacting with a conditionally cooperative other. Corresponding yoked controls were not expected to become cooperative. The availability of social comparison with an outcome which was smaller than the mutually cooperative outcome but larger than the mutually competitive out-come was expected to lead Own Gain Ss to more rapid learning of cooperation but not to affect the responses of corresponding yoked controls or of Relative Gain Ss. A 2 × 2 × 2 × 5 factorial design was used in which the factors were goal orientation (Own Gain vs Relative Gain), strategy of the other (conditionally cooperative vs yoked control), the availability vs unavailability of the social comparison, and trials. The results strongly supported each of the expectations. The results were discussed in terms of how the operation of the reward mechanism would be affected by the operation of some other social psychological processes.     

The effects of censorship and attractiveness of the censor on attitude change

The effects of censoring a communication, overriding the censor, and the attractiveness of the censor on the potential audience's attitude and desire to hear the communication were studied. Subjects were told that a speech which they were to have heard had been censored by a positively, negatively, or neutrally evaluated group. Some subjects were told that the experimenter had decided to override the censor and that they would hear the communication. Other subjects were told they would not hear the censored communication. The results indicated that censorship, regardless of the attractiveness of the censor, caused the potential audience to change their attitudes toward the position to be advocated by the communication and to increase their desire to hear that communication. These effects were interpreted as resulting from the arousal of psychological reactance. When the censor was overriden and the audience felt that they would hear the communication, their desire to hear it decreased. Further, subjects who had been told that a positively evaluated group had censored the speech changed their attitudes away from the position to be advocated by the communication while subjects who believed that a negative group had censored the speech changed their attitudes toward the position of the communication. These results were interpreted as evidence of cognitive balancing.