Discrimination learning and stimulus generalization by impulsive and reflective children

The proposition that impulsive children inhibit expressive behavior less than reflective children was investigated by providing third grade impulsive and reflective boys with either differential or nondifferential forms or successive discrimination training prior to tests for stimulus generalization. Consistent with specific predictions derived from Spence's theory on the roles of excitation and inhibition, it was found that: (a) Reflectives acquired the discrimination more rapidly, (b) reflectives achieved a higher level of discriminative performance, (c) impulsives exhibited more variable response reates during the nonreinforced stimulus, and (d) the type of training interacted with the child's conceptual tempo to determine the elevation and shape of the post-discrimination generalization gradients. The results provide support for the construct validity of the Matching Familiar Figures Test of reflectivity-impulsivity.     

Discrimination and generalization by rats of temporal stimuli lasting for minutes

In three experiments, rats learned to respond differentially to reinforced and nonreinforced trials when the length of the intertrial interval (ITI) predicted the trial outcome (reinforcement or nonreinforcement). Rats in control groups, for whom the length of the ITI did not predict the outcome, did not show differential performance on nonreinforced and reinforced trials. Generalization gradients obtained following discrimination training were comparable to those obtained following discrimination training with other types of discriminative stimuli. That is, groups which had shown differential performance in discrimination training yielded generalization gradients with fastest speeds at the previously reinforced ITIs, slowest speeds at the previously nonreinforced ITIs, and intermediate speeds at ITIs of intermediate length. Control groups yielded flat gradients across all ITIs tested. These effects were shown for relative time discrimination (short time = reinforcement, long time = nonreinforcement, or the reverse) and also for an absolute time discrimination (long and short time = reinforcement, middle time = nonreinforcement or the reverse). This method was effective for time duration measured in minutes rather than seconds, as is more commonly the case.     

Natural concepts and generalization classes

The results of an experiment performed by Herrnstein, Loveland, and Cable (1976) show that pigeons possess concepts that are not based on common elements. The conclusion they draw from these results is that these concepts are largely determined by genetic factors. In the present paper it is argued that, at least for some of the concepts, the conclusion is incorrect. These concepts-called here uncommon generalization classes-were acquired by the pigeons as a consequence of certain experiences through which they went during the experiment. The discussion will also suggest the fruitfulness of replacing the vague and misleading notion of concept by the more adequate notion of generalization class.     

Octave generalization and tune recognition

An experiment was performed to investigate whether or not we are able to use octave generalization in recognizing tunes. The firat half of the tune “Yankee Doodle” wu chosen as the test sequence. This was universally recognized when played in any one of three octaves. However, when the sequence was played in identical fashion. except that each note was chosen randomly from one of the same three octaves, the percentage correct recognition was not significantly different from that obtained when the sequence was played as a series of clicks with the pitch information omitted but the rhythmic information retained. It is concluded that tune recognition takes place along a channel which is independent from that which gives rise to octave generalization. The relevance of this finding to the theory of music recognition proposed by Deutsch (1969) is discussed.     

Sample selection and inductive generalization

In two experiments with adults (N=126), we examined the influence of sampling procedure on inductive generalization. In predicate sampling, participants learned the category identity of individuals known to possess some property. In subject sampling, individuals selected for category identity were discovered to possess a novel property. In both experiments, sampling procedure influenced induction. Predicate sampling resulted in very narrow generalization, whereas subject sampling yielded a fairly high and constant rate of projection. Differences in confidence of generalizations were also observed. Conditions in which evidence was described as randomly sampled from a collection of animals yielded a consistent decrease in projections as predicted by similarity-based models. The results are presented as support for an evidence-based view of induction.     

Stimulus generalization of behavioral history: Interspecies generality and persistence of generalization gradients

Four pigeons were exposed to a tandem variable-interval (VI) fixed-ratio (FR) schedule in the presence of a 50-pixel (about 15 mm) square or an 80-pixel (about 24 mm) square and to a tandem VI differential-reinforcement-of-low-rate (DRL) schedule when a second 80-pixel or 50-pixel square was present. The values of the VI and FR schedules were adjusted to equate reinforcement rates in the two tandem schedules. Following this, a square-size continuum generalization test was administered under a fixed-interval (FI) schedule or extinction. In the first testing session, response frequency was a graded function of the similarity of the test stimuli to the training stimuli for all pigeons. These systematic generalization gradients persisted longer under the FI schedule than under extinction.     

Label training and auditory generalization

To investigate the Miller-Dollard hypothesis (Social learning and imitation, New Haven: Yale University Press, 1941) that verbal labels increase distinctiveness of cues, generalization gradients to pure tones were obtained before and after label training. One group was trained to label all seven tones in an array and another only the middle tone. Three additional groups controlled for nonverbal factors. Before training, gradients were characterized by progressive loss of stimulus control with exposure to the generalization test stimuli. The main effect of possession of labels was to retard this loss, but only in tests where S+ was a labeled stimulus. While the specificity of label effects was in line with the Miller-Dollard hypothesis, the finding that labels did not confer a clear advantage at the start of testing was not. It was suggested that the unlabeled stimuli may have been sufficiently distinct to mask label effects and that interference generated by the test stimuli reduced distinctiveness to levels needed for such effects to emerge.     

Reliability generalization: a viable key for establishing validity generalization

Even with radical restriction of range, reliability coefficients from 10 studies gave an average interstudy value of .74, suggesting constancy of reliability over diverse experiments. A value from a new test can help index reliability of tests not previously studied.     

Causal-based property generalization

A central question in cognitive research concerns how new properties are generalized to categories. This article introduces a model of how generalizations involve a process of causal inference in which people estimate the likely presence of the new property in individual category exemplars and then the prevalence of the property among all category members. Evidence in favor of this causal-based generalization (CBG) view included effects of an existing feature's base rate (Experiment 1), the direction of the causal relations (Experiments 2 and 4), the number of those relations (Experiment 3), and the distribution of features among category members (Experiments 4 and 5). The results provided no support for an alternative view that generalizations are promoted by the centrality of the to-be-generalized feature. However, there was evidence that a minority of participants based their judgments on simpler associative reasoning processes.     

不容异说与歧视

宽容从绝对君主制下的一项实用主义原则,演变为民主政治下宗教多元主义的一项必不可少的原则,本文对此进行了溯源。作者区分了两种不同的宽容：一是对待外人的一般宽容,即对被人们认为是弱者的宽容;二是建立在不同世界观上彼此形成共识基础上的宽容。后者的宽容允许宗教和民主政治共存于多元论的环境中,并为文化多元主义和平等主义之间的和解奠定基础。