Arithmetic fact mastery in young children: a longitudinal investigation

Children with poor arithmetic fact mastery (n=45) at the end of third grade were compared to grade-level peers with good arithmetic fact mastery (n=60) in competencies related to reading and mathematics. Children were assessed longitudinally across second and third grades. When predictor variables such as IQ were held constant, the poor fact mastery and good fact mastery groups performed at about the same level and progressed at a comparable rate on math story problems and on broad reading achievement. The groups also progressed at a comparable rate on broad math achievement, although children with poor fact mastery performed at a significantly lower level. Children with poor fact mastery showed remarkably little growth on timed number facts during the study period, despite normal growth in other areas of mathematics. Deficits in fact mastery are highly persistent and appear to be independent of reading and language abilities.     

Goal-driven modulation of stimulus-driven attentional capture in multiple-cue displays

Six location-cuing experiments were conducted to examine the goal-driven control of attentional capture in multiple-cue displays. In most of the experiments, the cue display consisted of the simultaneous presentation of a red direct cue that was highly predictive of the target location (the unique cue) and three gray direct cues (the standard cues) that were not predictive of the location. The results indicated that although target responses were faster at all cued locations relative to uncued locations, they were significantly faster at the unique-cue location than at the standard-cue locations. Other results suggest that the faster responses produced by direct cues may be associated with two different components: an attention-related component that can be modulated by goal-driven factors and a nonattentional component that occurs in parallel at multiple direct-cue locations and is minimally affected by the same goal-driven factors.     

Open-ended categorization of chick-a-dee calls by black-capped chickadees (Poecile atricapilla)

The authors trained black-capped chickadees (Poecile atricapilla) in an operant discrimination with exemplars of black-capped and Carolina chick-a-dee calls, with the goal of determining whether the birds memorized the calls of conspecifics and heterospecifics or classified the calls by species. Black-capped calls served as both rewarded (S+) and unrewarded (S-) stimuli (the within-category discrimination), whereas Carolina chick-a-dee calls served as S-s (the between-category discrimination) in the black-capped chick-a-dee call S+ group. The Carolina call S+ group had Carolina calls as S+s and S-s (within-category) and black-capped calls as S-s (between-category). Both groups discriminated between call categories faster than within a call category. In 2 subsequent experiments, both S+ groups showed transfer to novel calls and propagation back to between-category calls. The results favor the hypothesis that the acoustically similar social calls of the 2 species constitute separate open-ended categories.     

Somatoform dissociation in eating-disordered patients

This study investigated the role of somatoform dissociation in eating disorders and pathological eating behaviour, relative to the established association of eating pathology with psychological dissociation. The participants were 131 women with DSM-IV diagnoses of anorexic or bulimic disorders and 75 women who had no such disorder. Each woman completed measures of psychological and somatoform dissociation, as well as a measure of bulimic attitudes. The current presence or absence of specific bulimic behaviours was identified during the clinical interview. Levels of both forms of dissociation were higher in the women who had diagnoses of disorders with a bulimic component (bulimia nervosa; anorexia nervosa of the binge/purge subtype) than in the non-clinical or restrictive anorexic women. Somatoform dissociation showed particularly strong links with the presence of bulimic behavioural features (excessive exercise, laxative abuse, diet pill abuse, diuretic abuse) and with bulimic attitudes. The formulation and treatment of cases where there are bulimic features is likely to be enhanced by the assessment of somatoform dissociation.     

Stereotype threat and arousal: effects on women's math performance

Theories of arousal suggest that arousal should decrease performance on difficult tasks and increase performance on easy tasks. An experiment tested the hypothesis that the effects of stereotype threat on performance are due to heightened arousal. The authors hypothesized that telling participants that a math test they are about to take is known to have gender differences would cause stereotype threat in women but not in men. In the experiment, each participant took two tests--a difficult math test and an easy math test. Compared to women in a "no differences" condition, women in the "gender differences" condition scored better on the easy math test and worse on the difficult math test. Men's performance was unaffected by the manipulation. These data are consistent with an arousal-based explanation of stereotype threat effects. Data were inconsistent with expectancy, evaluation apprehension, and persistence explanations of the stereotype threat phenomenon.     

The CS-preexposure effect in conditioned taste-aversion learning in golden hamsters

In Experiment 1, golden hamsters were injected with either 0.9% saline or the nausea-inducing agent, lithium chloride (LiCL), immediately after consuming a flavored diet that was either novel or familiar. The LiCl-induced aversion was strong in hamsters for which the flavored diet was novel, but no significant aversion was observed in hamsters that were familiar with the flavored diet. In Experiment 2, the strength of the LiCl-induced aversion was related inversely to the amount of conditioned-stimulus (CS) preexposure and directly to the duration of the preexposure-conditioning interval. Thus, although some previous researchers have suggested that hamsters may not demonstrate the CS-preexposure effect in a conditioned taste-aversion paradigm, they clearly did so under the conditions of the present experiments, and moreover, the characteristics of the CS-preexposure effect in hamsters were generally similar to those observed in rats.     

Trichotillomania (hair pulling) in toddlers

Although the clinical diagnosis of trichotillomania has been observed for more than a century, not until the last decade has there been a focus on this diagnosis in early childhood. This small case series focuses on the clinical evaluation of 10 toddlers, average of 26 mo., presenting at a specialty child and adolescent psychiatry clinic with hair pulling. Authors suggest that hair pulling in this age group might better be conceptualized as an anxiety disorder.     

Descartes's blind man revisited: bimanual triangulation of distance using static hand-held rods

Analogous to binocular convergence, we tested Descartes's proposal that a blind person could triangulate distances using crossed hand-held rods by sensing hand separation and wrist angles. In Experiment 1, 22 participants judged distances to loci at 4 distances, 18-36 in. (45.7-91.4 cm), at 5 eccentricities, 0-12 in. (0-30.5 cm) left and right of center. Participants reliably differentiated and scaled distances. The median individual multiple correlation (actual distances and eccentricities vs. judged distances; nonlinear with eccentricity) was .91 (range, .75 to .95; group R = .98). In Experiment 2, 2 experienced observers judged 7 distances, 30-66 in. (76.2-167.6 cm) at 7 eccentricities, 0-18 in. (0-45.7 cm) left and right. Results replicated those of Experiment 1, with nonlinear multiple Rs of .97 and .99 for the 2 participants. Bimanual triangulation supported reliable distance judgments, comparable to binocular distance perception. No evidence of perceptual learning was found.