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.     

From response-set to prediction hypotheses: Rule acquisition among preschoolers and second graders

It was proposed that prediction hypotheses do not emerge full blown in the repertoire of the young child. Instead, the component units out of which predictions are consolidated (win-stay, lose-shift) are acquired independently and at different rates. The young child's behavior is at first dominated by response sets in which the win and lose components involve the same action (win-stay, lose-stay or win-shift, lose-shift). The components of response sets must be separated and coordinated with task-relevant information before appropriate components are consolidated to yield prediction hypotheses. A combination of learning-set and blank-trial procedures was used to evaluate this conception with preschoolers (mean CA = 4:1) and second graders (mean CA = 7:6). Results revealed that children of both age levels exhibited response patterns that corresponded to hypotheses in most of their probes (.89 to. 98). The striking finding was the relative weakness of win-stay on object cues at the outset of acquisition, particularly among the younger children. In contrast. lose-shift object was strong from the outset among children of both age levels. Once the two components (win-stay object, lose-shift object) were consolidated, the resulting scheme was durable, in that transfer to more complex problems was nearly perfect. Children who did not achieve criterion (in 70 problems) failed because they exhibited mostly position hypotheses and/or because the strength of win-stay object remained weak throughout all sessions.     

The effects of a memory aid on three types of conservation judgments

Twelve boys and 12 girls at each of 3 ages (4, 5, and 6 years) were tested on three types of conservation judgments (qualitative, quantitative, and equivalence) on both continuous and discontinuous substances. Half of the subjects were provided a memory aid while the other half were not. Conservation ability was determined both with and without verbal justification. The memory aid increased the number of equivalence conservation responses only when verbal justification was not required. The number of subjects conserving on each of the three tasks varied as a function of the scoring criteria used. Type of materials, sex, and age effects were found. The role of transitive inferences and memory in the equivalence conservation task was discussed. Inconsistencies in previous research due to different scoring techniques were noted.