Child performance on discrimination tasks: Effects of amount of stimulus variation

Two independently conducted studies investigated stimulus variation effects on children's discrimination learning. The stimuli in the first study were generated by a conjunctive rule and were presented in pairs. Mean trials to criterion was significantly lower for the single-feature change treatment (17.4) than for the multiple-feature change treatment (29.9). Single-feature change-treatment transfer scores were significantly higher only for stimuli that differed in terms of one of the features. The second study not only replicated the initial finding concerning the single-feature change treatment but also found that students made more errors in reaching criterion when stimuli were generated by an exclusive disjunctive rule and were presented singly. For all tasks, the single-feature change treatment with stimuli presented in pairs was accompanied by fewer errors to criterion than the other treatments.     

Behavioral inference in young children

Three experiments are reported on behavioral inference in children of 3 to 5 years of age. In each experiment the children learned two separate sequences of behavior which they were required to put together in the final test stage in order to obtain a reward. In the first experiment moderate levels of behavioral inference were obtained, although a relatively high proportion of children failed to respond in the test phase. In the second experiment different instructions were used in the test phase, the number of nonresponders was greatly reduced and a much higher proportion of children showed behavioral inference. The third experiment obtained similar results under conditions which excluded the possibility of mediation during a memory test, which was included in the previous experiments. It was concluded that behavioral inference is found, under suitable conditions, in children as young as 3-years-old, and that reports by other investigators of failure to find such inference up to the age of about 8 were due to problems with apparatus and instructions.     

Control of observing by antecedent stimuli

Five pigeons were run on a one-key discrete trials observing procedure. Trial onset was signaled by a white or yellow key light. Pecks in white or yellow intermittently produced S⁺ and S⁻, green and red key lights that signaled whether the trial would end with response-independent grain reinforcement or nonreinforcement. In the Redundant conditions, white and yellow were correlated with trial outcome, making S⁺ and S⁻ redundant. In the Informative condition, white and yellow were uncorrelated with trial outcome, so that S⁺ and S⁻ provided new information. During the Informative condition, all birds responded in the formerly positive, now uncorrelated color at higher rates than they did during the preceding or succeeding Redundant conditions, in which that same color was positively correlated with primary reinforcement. This result confirmed the prediction that an animal will observe at higher rates in the absence of reinforcement-correlated cues than in their presence.     

Behavioral contrast produced by a signaled decrease in local rate of reinforcement

Pigeons' key pecking in the presence of one stimulus (S1) was reinforced according to a response-dependent variable-interval schedule. Pecking rate during S1 increased (behavioral contrast) when a second stimulus (S2) [associated with either a response-dependent fixed-interval schedule (Experiment I) or a response-independent reinforcement schedule in which reinforcement availability was signaled by visual (Experiment II) or temporal (Experiment III) stimuli] alternated with S1. These experiments suggest that a discriminable, signaled decrease in local reinforcement rate during S2 is an antecedent of the behavioral contrast response rate increases during S1.     

Verbal rehearsal and selective attention in children with learning disabilities: A developmental lag

To investigate the development of verbal rehearsal strategies and selective attention in learning disabled children, Hagen's Central-Incidental task was administered to younger learning disabled (M CA = 8.68 years) and normal (M CA = 8.62 years) boys in Experiment 1 and to intermediate (M CA = 10.18 years) and older (M CA = 13.48 years) learning disabled boys in Experiment 2. Also, in Experiment 2, an experimentally induced verbal rehearsal condition was included to determine its effects on serial recall and selective attention performance. In Experiment 1, the serial postion curve of the normals revealed both a primacy and a recency effect, whereas that of the learning disabled revealed a recency effect only. In Experiment 2, both the intermediate and the older learning disabled exhibited both primacy and recency effects under both standard and rehearsal conditions. A developmental analysis of central recall for the three learning disabled groups revealed constant age-related increases in overall central recall and in primacy recall. That the normals recalled more central, but not more incidental, information than the learning disabled in Experiment 1 suggests that the learning disabled are deficient in selective attention. Correlational findings suggest that the selective attention of the learning disabled improves with age. The results were interpreted as support for the hypothesis of a developmental lag in the learning disabled population.     

解惑

该文从孔子“不惑”的提法入手,尝试把“惑”作为普遍的人类精神现象进行探讨。在区分惑与无知,惑与怀疑的不同意识特征之后,作者对惑的多样性作分类描述。在此基础上,把孔子与庄子当作有助于解惑的两类不同的经典思想资源加以评介,并以王国维为例,讨论其惑所包含的心理与时代因素。文章最后以对“解”的理解结束全文。