Structural complexity as a determinant of serial pattern learning

A new methodology extends the study of serial pattern learning to nonhuman organisms by constructing patterns using elements that are both familiar and motivationally meaningful to animals. Two experiments examine the ability of rats to anticipate various quantities of food as measured by running times in a runway when the quantities occur in a serial order. In Experiment 1, a serial monotonic pattern (14-7-3-1-0 food pellets) produced more rapid learning and more accurate anticipation of the various quantities (“tracking”) than a serial nonmonotonic pattern (14-1-3-7-0 food pellets), particularly with respect to the final 0-pellet element. In Experiment 2, the same monotonic pattern generated faster learning and more accurate anticipation of pattern elements than a weakly monotonic pattern (14-5-5-1-0 pellets). Associative explanations including simple excitatory or inhibitory effects, temporal anticipation, reinforcement contrast, and the number and discriminability of pairwise associations are not adequate to account for the data. Rather, the formally defined structural complexity of each pattern adequately predicts its relative difficulty.     

Across-reinforcement blocking effects in a mediational test of the CS's general signaling property

Rats received Pavlovian aversive (shock) conditioning in which white noise was established for independent groups as a CS+, CSo, or CS−. Then, in an easy (light-dark) T-maze discrimination, the CS was presented either immediately following choice (Locus 1) or at the food cup in the goal (Locus 3), contingent upon either a food-reinforced (right) or nonreinforced (wrong) response. When presented at Locus 3, the CS+ facilitated and the CS− retarded learning for CS/right subjects, with these effects being exactly reversed but somewhat less pronounced for CS/wrong subjects. However, when the CS was presented at Locus 1, the CS+ and CS− effects for both response contingencies were attenuated. These findings oppose an interpretation of the CS's function as a general cue or transformed signal for the presence or absence of the new appetitive reinforcer and argue instead for across-reinforcement blocking effects: By signaling in the presence of food reinforcement an outcome (safety or shock) which is consonant with or discrepant from the “good” outcome obtained, the CS− blocks (retards) and the CS+ counterblocks (enhances) the association of food reinforcement and the S^D; conversely, in the presence of nonreinforcement (a “bad” outcome), the CS− counterblocks and the CS+ blocks inhibitory conditioning to the S^Δ. As in Kamin's (1968) original research, such effects are attenuated when the CS is presented early in the compound, distal to the reinforcer.     

A comparison of operant licking and lever pressing in the rat

Two groups of rats were trained on a signaled, free-operant, avoidance procedure to lick or to lever press in order to avoid shock while water-deprived or satiated and, in the case of licking, while ingesting deionized water, isotonic saline, or 10% sucrose. The most effective avoidance licking occurred while the rats were water-deprived and ingesting 10% sucrose. Water deprivation level had no effect on lever pressing for shock avoidance. Two other groups of rats were operantly conditioned to lick or to lever press for food pellets while waterdeprived or satiated and, in the case of licking, while ingesting deionized water or 10% sucrose. The most effective licking for food reinforcement occurred while the rats were water-deprived and ingesting 10% sucrose. Water deprivation level had no effect on lever pressing for food reinforcement. The data indicated that effective operant licking must be supported by factors related to water regulation and taste palatability.     

Dissonance theory,self-perception and the bogus pipeline

Studied attitude change following counter-attitudinal advocacy where there was little incentive for subject compliance in an attempt to compare dissonance and self-perception theory predictions. The extent of attitude change was determined either by self-report or by having subjects predict their own true attitudes purportedly monitored by the experimenter using a ‘bogus pipeline’. Forty-eight male and female subjects, students from an introductory Psychology course, were invited to take part in a study of Current Campus Issues. They wrote a short statement that argued against an issue for which they had previously held a positive attitude. Results indicate that there was a significant attitude change in both conditions (p < .003). Attitude change under these circumstances is more successfully explained by the self-perception theory than dissonance theory.     

A different form of agraphia: Syntactic writing errors in patients with motor speech and movement disorders

Three patients are described who displayed syntactic writing errors in combination with a motor speech disturbance and impaired motor limb function. Two of the patients had bulbar amyotrophic lateral sclerosis (ALS). Agraphia appeared when verbal communication was no longer possible. Autopsy in one patient disclosed only lesions consistent with ALS. The third patient had palilalia and chorea and, although not aphasic, his written language showed persistent syntactic errors. We hypothesize that the agraphia in these patients occurred because of the combination of disordered feedback from the motor speech apparatus and limbs.