Differentiation at higher levels of cognitive ability: evidence from the United States

Most psychologists and educators assume that intelligence is a linear construct, meaning that smart people simply have more intelligence than their less gifted peers. Likewise, individuals with mental retardation are thought to have less intelligence. In contrast to this widely accepted belief, the authors posed an alternative hypothesis--that intelligence is qualitatively different in various populations. Using factor analysis of a standardization sample of the Woodcock-Johnson Test of Cognitive Ability (R. W. Woodcock & M. B. Johnson, 1989), the authors examined the nature of intellect across ability. Results indicated that the amount of variance attributable to Spearman's g declined as measured intellectual ability increased.     

Working memory capacity and the top-down control of visual search: Exploring the boundaries of "executive attention"

The executive attention theory of working memory capacity (WMC) proposes that measures of WMC broadly predict higher order cognitive abilities because they tap important and general attention capabilities (R. W. Engle & M. J. Kane, 2004). Previous research demonstrated WMC-related differences in attention tasks that required restraint of habitual responses or constraint of conscious focus. To further specify the executive attention construct, the present experiments sought boundary conditions of the WMC-attention relation. Three experiments correlated individual differences in WMC, as measured by complex span tasks, and executive control of visual search. In feature-absence search, conjunction search, and spatial configuration search, WMC was unrelated to search slopes, although they were large and reliably measured. Even in a search task designed to require the volitional movement of attention (J. M. Wolfe, G. A. Alvarez, & T. S. Horowitz, 2000), WMC was irrelevant to performance. Thus, WMC is not associated with all demanding or controlled attention processes, which poses problems for some general theories of WMC.     

Luminance gradient can break background-independent lightness constancy

A display with a luminance gradient was shown to induce a strong lightness illusion (Logvinenko, 1999 Perception 28 803-816). However, a 3-D cardboard model of this display was found to produce a much weaker illusion (less than half that in the pictorial version) despite the fact that its retinal image is practically the same. This is in line with the hypothesis that simultaneous lightness contrast is solely a phenomenon of pictorial perception (Logvinenko et al, 2002 Perception 31 73-82). The residual lightness illusion in the 3-D model can be accounted for by the fact that this model is a hybrid display. Specifically, while it is a real object, a pictorial representation (of the illumination gradient) is superimposed on it. Thus, lightness in the 3-D display is a compromise between two opposite tendencies: the background-independent lightness constancy and the lightness illusory shift induced by the luminance gradient.     

Working-memory capacity, proactive interference, and divided attention: limits on long-term memory retrieval

Two experiments examined how individual differences in working-memory capacity (WM) relate to proactive interference (PI) susceptibility. We tested high and low WM-span participants in a PI-buildup task under single-task or dual-task ("load") conditions. In Experiment 1, a finger-tapping task was imposed during encoding and retrieval of each list; in Experiment 2, tapping was required during encoding or retrieval. In both experiments, low spans showed greater PI than did high spans under no load, but groups showed equivalent PI under divided attention. Load increased PI only for high spans, suggesting they use attention at encoding and retrieval to combat PI. In Experiment 2, only low spans showed a dual-task cost on List 1 memory, before PI built up. Results indicate a role for attentional processing, perhaps inhibitory in nature, at encoding and retrieval, and are discussed with respect to theories of WM and prefrontal cortex function.     

Author Index Volume 4

Authors Index

Author Index Volume 4     

Discontinuity of seen motion reduces the visual motion aftereffect

Would a motion-picture film of a rotating spiral induce a spiral aftereffect? This question was studied in two experiments in which Ss viewed an animated film of circles collapsing to a point. The rate of apparent motion of the collapsing circles and the discontinuity of motion—the length of jump between successively projected circles—were varied independently. A visual aftereffect like the spiral aftereffect was created. The aftereffect increased in strength and duration with the rate of motion, but at all rates of motion it declined as discontinuity of motion increased. The results are taken as evidence that motion aftereffects are caused by selective fatigue of small, directionally sensitive motion-receptive fields.     

Semantic interpretation effects on memory for faces

Five experiments investigated the effects of semantically interpreting faces on their recognition. Experiment 1 demonstrated that faces could meaningfully be related to occupational categories. In Experiments 2–5, each of a set of faces was presented with either the label of a congruent occupational category or a noncongruent label. Presenting a face with a congruent occupational label was found to enhance recognition that the face had previously been seen (Experiments 2–4), but congruent labeling also impaired the detection of distractor faces that matched previously seen faces’ categories (Experiments 3 and 4). In a forced-choice recognition test, in which distractors were highly similar to originally seen faces, congruent occupational labeling failed to increase recognition of previously seen faces (Experiment 5). These results indicate that interpreting faces, with respect to stereotyped categories, ratherthan improving a physical codein memory, led to theformation of a semantic code, which increased recognition of old items at the expense of the detection of new items. Another general finding was that faces that were rated more stereotypical were more recognizable, regardless of the accompanying label.     

Psychiatric Symptomatology and Family Functioning in Children and Adolescents with Spina Bifida

The purpose of this study was to (a) examine the occurrence of psychiatric symptomatology in children and adolescents with spina bifida, (b) investigate the relationship between psychiatric features and aspects of disability, and (c) explore the impact of spina bifida and psychiatric status on family functioning. Fifty-four children and adolescents ages 6 to 18 years (M = 12.94, SD = 3.59) were examined. Parents completed the Child Symptom Inventory (CSI) and the Family Assessment Device (FAD). Using the CSI, a psychiatric diagnostic screen, 43% of the sample obtained one, and 13% obtained two or more screening cutoff scores reflective of psychiatric diagnoses. The two most prevalent diagnostic categories were Attention-Deficit/Hyperactivity Disorder (33%) and Oppositional Defiant Disorder (13%). The sample as a whole exhibited elevated levels of clinical symptoms, with internalizing symptoms more prominent than externalizing symptoms. No differences in diagnostic categories or overall symptomatology were found based on age, gender, ambulation status, or lesion level. Overall symptom counts were positively correlated with scales on the FAD reflecting problematic family functioning (.42–.65). Results suggest that psychiatric symptomatology occurs at a high rate in children and youth with spina bifida. Although ADHD was the modal diagnostic category, the sample as a whole exhibited extensive psychiatric symptoms independent of specific diagnostic categories. Psychiatric symptoms were also associated with increased problematic functioning in families.