Conservation acquisition, maintenance, and generalization by mentally retarded children using equality-rule training.

To teach conservation to mildly retarded, preoperational preadolescents (9 to 12 years old), a number-representational system was used to mediate the invariance of quantity as part of "equality-rule" training. Before viewing a perceptually misleading configuration of either two equal quantities or two unequal quantities entailing the dimensions of number or length, participants learned that equality involved the assignment of two identical numbers and inequality the assignment of two different numbers. These numbers were then applied to the actual quantities and became the basis for rule statements that were rehearsed, memorized, and subject-generated each time the quantities were transformed into a new configuration. Following equality training, correct judgments and verbal justifications of conservation were high (M greater than or equal to 85%) during both immediate and delayed post-tests and for near-generalization (number and length) and far-generalization (weight, liquid substance, and solid substance) tasks. In contrast, the post-test levels of comparable participants given learning-set (LS) training, LS plus verbal-rule training (a combination of statements about identity, negation, and compensation), or no training at all were substantially and significantly lower. Equality training is of theoretical and practical interest because of its potential to teach a symbolic representational rule that directly and meaningfully articulates the quantitative properties of objects and counteracts the overreliance on task-specific and faulty perceptual cues inherent in the conservation task.     

Context-dependent effects on analogical transfer

The role of context in facilitating analogical transfer was investigated in two experiments. In both experiments, subjects first read two stories that were analogous to Duncker’s (1945) radiation problem. Later, subjects attempted to solve the radiation problem. In Experiment 1, the radiation problem was presented in a different context than that of the stories, and followed them by 6 min. Transfer was observed in subjects who were prompted to use the earlier stories in solving the problem. However, the solution frequency of subjects not given such prompts did not differ from control levels. In Experiment 2, the radiation problem was presented in the same context as the earlier stories to some subjects, and in a different context to others. The timing of the radiation problem also was varied. When a 6-min interval separated the stories from the radiation problem, transfer was a function of context, with weak transfer being observed in the samecontext condition, and no transfer being observed in the different-context condition. At a 45-sec delay, transfer was again observed in the same~ontext condition, and a nonsignificant trend toward transfer was observed in the different-context condition. The results were interpreted as indicating that context facilitates the retrieval of relevant problem-solving schemas, and as suggesting that the possession of relevant schemas is not sufficient to produce analogical transfer.     

Fixed ratio and extinction performance of infants in the second year of life

Five 14(1/2)- to 19(1/2)-month-old infants were trained to lever press for snacks on small fixed ratio schedules of reinforcement. Within four to nine sessions, responding under FR 10 was established for four subjects and FR 15 for the other. Each subject's last session revealed behavioral patterns similar to animal and human FR trained subjects-a high and constant ratio rate, mixed with a zero rate following reinforcements. Deviations were mostly in the form of prolonged and variable post-reinforcement pauses. These and other irregularities were probably due to the limited deprivation conditions and improper training procedures in which the ratio (for two subjects) was ascended too early and too quickly. Extinction was instituted during the last session. The degree to which extinction performance matched that of other organisms depended upon how stable and "ratio-like" performance was during conditioning.     

EFFECTS OF DIRECT,INTERMITTENT, AND VICARIOUS REINFORCEMENT PROCEDURES ON THE DEVELOPMENT AND MAINTENANCE OF INSTRUCTION-FOLLOWING BEHAVIORS IN A GROUP OF YOUNG CHILDREN1

A group of young children (mean age: 2.5 yr) were instructed to follow different requests by a teacher in a day-care setting. Experiment I verified that mean group instruction following was low (10%) despite the opportunity for “observational learning”, i.e., the group of 12 children could watch a nonreinforced adult comply with the teacher's request. In Experiment II, when positive consequences were provided contingent on the adult model's behavior, mean group instruction following was relatively unaffected (14%). When direct reinforcement was given to four peer models, each for several sessions, the individual performances of three of the four peer models was elevated (from 50% to 80%); however, the mean performance of the remaining nonreinforced children (N = 7) was only moderately affected (21%). When reinforcement contingencies were again changed, so that each group member was provided direct, but intermittent reinforcement, mean group performance increased substantially to levels of over 70%. Once instruction following was high, presentation of reinforcement only to one peer model sufficed to maintain performance whereas earlier, this same vicarious reinforcement procedure had failed to establish group compliance. The maintenance of instruction-following behavior when reinforcement was applied solely to one child was interpreted mainly in terms of a high resistance to extinction following a history of intermittent reinforcement rather than a “vicarious”- or “self”-reinforcement mechanism. Finally, removal and re-introduction of group intermittent reinforcement, respectively, lowered performance (to levels of 40%) and elevated (to levels of 65%) the group's performance.     

Repetition priming across the adult lifespan--the long and short of it

Previous reports suggest that repetition priming (i.e., enhanced processing of a stimulus after experience with that stimulus) is long lasting and impervious to the effects of age, in contrast to the pattern found with explicit memory. However, the nature of repetition priming in aged individuals remains unclear, as conflicting findings have also been reported. We used a longitudinal design to examine how repetition priming is affected by multiple stimulus repetitions (three presentations) and different delay intervals (no delay, 1 day, 1 week, and 1 month) in young adults, as well as in two groups of aging adults (young-elderly and old-elderly). Our findings extend previous reports that priming is long lasting, even when 1 month intervenes between the initial experience with an item and the subsequent priming test of that item (Cave, 1997), and is relatively impervious to the effects of age (Mitchell, et al., 1990). In addition, a more detailed characterization of priming and the effects of aging was revealed. Although priming is long lasting, remaining significant even at the month delay for all groups, it did decline over time and the rate of that decline differed with age. Both young-elderly and old-elderly groups showed a marked drop-off at 1 day, whereas young adults did not show a decline until 1 week. All groups benefited from multiple repetitions; however, this benefit disappeared at the month delay (in contrast to recognition memory, where the benefit remained significant). These findings support the assertion that repetition priming and explicit memory reflect the operation of distinct systems, and that these systems may undergo different rates of change in aging.     

Conditionalization,Reflection, and Self-Knowledge

Van Fraassen famously endorses the Principle of Reflection as a constraint on rational credence, and argues that Reflection is entailed by the more traditional principle of Conditionalization. He draws two morals from this alleged entailment. First, that Reflection can be regarded as an alternative to Conditionalization – a more lenient standard of rationality. And second, that commitment to Conditionalization can be turned into support for Reflection. Van Fraassen also argues that Reflection implies Conditionalization, thus offering a new justification for Conditionalization. I argue that neither principle entails the other, and thus neither can be used to motivate the other in the way van Fraassen says. There are ways to connect Conditionalization to Reflection, but these connections depend on poor assumptions about our introspective access, and are not tight enough to draw the sorts of conclusions van Fraassen wants. Upon close examination, the two principles seem to be getting at two quite independent epistemic norms. My thanks to Frank Arntzenius, Barry Loewer, Chris Meacham, John Hawthorne, and an anonymous referee for their helpful discussion and criticism. Special thanks to Bliss Kern for bringing the topic to my attention.