Infantile handling and the facilitation of discrimination and reversal learning

One group of rats was removed from their home cage and received daily handling from Days 3-21, while the control group of litter mates remained in the cage and did not receive any treatment. On Day 22 all rats were weaned and they were housed in individual cages until they were 60 days old. After two pretraining days, subjects were given daily blocks of one free and three forced trials in the T-maze and were rewarded with food after making the correct response. Following 20 days of training and testing on black-white discrimination, subjects were given 10 days of reversal training with four daily trials. Results indicate that the handled animals showed faster running and a greater number of correct choices than the control rats during both the acquisition and reversal learning phases of the experiment.     

A window for the study of prenatal sex hormone influences on postnatal development

In humans, the influence of prenatal sex hormones on the fetal brain and subsequent postnatal development has had limited study because of the apparent inaccessibility of hormone levels in normal fetuses. We propose that amniotic fluid obtained via midtrimester amniocentesis can be assayed for fetal hormone levels during the period thought to be important for sexual differentiation of the brain. Amniotic fluid samples from midgestation (N = 70) were assayed for levels of testosterone and follicle-stimulating hormone, and significant sex differences were observed (ps less than .001), with some degree of overlap between the sexes. The possibility of applying hormone levels obtained from amniotic fluid to the study of postnatal development is discussed.     

Manual discrimination and identification of length by the finger-span method

Experiments were conducted on length resolution for objects held between the thumb and fore-finger. The just noticeable difference in length measured in discrimination experiments is roughly 1 mm for reference lengths of 10 to 20 mm. It increases monotonically with reference length but violates Weber's law. Also, it decreases when the subject is permitted to maintain a constant finger span between trials; however, it tends to increase when the nondominant hand is used. As would be expected from studies of other stimulus dimensions in other sense modalities, resolution is considerably poorer in identification experiments than in discrimination experiments. For stimulus sets that cover a broad range (90 mm), the total information transfer is roughly 2 bits; for those that cover a relatively small range (18 mm), it is roughly 1 bit. The data are analyzed and interpreted using analysis techniques and models that have been used previously in studies of audition (e.g., Durlach & Braida, 1969).     

Issues in cognitive-behavioral interventions in academic skill areas 1

In this paper, conceptual and methodological issues within three phases of CBM interventions in academic skills are analyzed: Acquisition, evaluation, and generalization. The goal of such analysis is threefold: To enhance understanding of observed problems, clarify specific conceptual issues, and highlight areas that need more conceptual clarification and more research.     

Links between local language competence and peer relations among Swiss and immigrant children: the mediating role of social behavior

The primary aim of this investigation was to evaluate a model in which children's social behaviors, including prosocial behavior, setting limits, and social withdrawal, were hypothesized to mediate the links between local language competence (LLC) and peer acceptance and victimization. Longitudinal data were collected via teacher and peer reports on 541 (286 boys and 255 girls) immigrant and Swiss native 5-to-6 year-old kindergarteners. Results showed the immigrant children were less fluent in the local language compared to native Swiss classmates. Moreover, results from structural equation models, with bootstrap tests of indirect effects, indicated that social behaviors mediated the link between LLC and the quality of children's peer relationships. Implications of these findings for school professionals are discussed, such as the need to help immigrant children make a smoother transition to their host communities by providing additional language and social supports while children acculturate and acclimate to their new surroundings and peer group.     

Music-reading expertise alters visual spatial resolution for musical notation

Crowding occurs when the perception of a suprathreshold target is impaired by nearby distractors, reflecting a fundamental limitation on visual spatial resolution. It is likely that crowding limits music reading, as each musical note is crowded by adjacent notes and by the five-line staff, similar to word reading, in which letter recognition is reduced by crowding from adjacent letters. Here, we tested the hypothesis that, with extensive experience, music-reading experts have acquired visual skills such that they experience a smaller crowding effect, resulting in higher music-reading fluency. Experts experienced a smaller crowding effect than did novices, but only for musical stimuli, not for control stimuli (Landolt Cs). The magnitude of the crowding effect for musical stimuli could be predicted by individual fluency in music reading. Our results highlight the role of experience in crowding: Visual spatial resolution can be improved specifically for objects associated with perceptual expertise. Music-reading rates are likely limited by crowding, and our results are consistent with the idea that experience alleviates these limitations.