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Biomedical subjects

G W Hynd

Publications and source records attributed to G W Hynd.

At least 55 records · Page 3Linked to original sources
PubMed1989

Neuropsychologic impairment in children with sickle cell anemia.

In this study, the neuropsychologic functioning of 21 children with sickle cell anemia and 21 sibling controls, age range 7 through 16 years, with no history of neurologic disease, was examined. Outcome measures included tests of intelligence, constructional praxis, memory, and academic learning. On the Wechsler Intelligence Scale for Children--Revised, the sickle cell group had a mean Full Scale IQ of 77.7 (SD 12.4) compared with 94.3 (SD 11.0) for the control group. The profile of test scores was similar for the two groups, with the sickle cell group scoring significantly lower than the control group on almost all cognitive measures. Both groups showed academic achievement to be commensurate with their measured intellectual ability. These results suggest that subtle but significant and widespread neuropsychologic deficits are associated with sickle cell anemia even in the absence of neurologic complications. When and by what process this neuropsychologic impairment is caused needs to be determined.

Adolescent↗
PubMed1987

Sociometric status of clinic-referred children with attention deficit disorders with and without hyperactivity.

Peer sociometric nominations of clinic-referred children given the diagnosis of Attention) Deficit Disorder with Hyperactivity (ADD/H) or Attention Deficit Disorder without Hyperactivity (ADD/WO) were compared to one another and to those of normal control children. Only children with ADD diagnoses in the absence of other major diagnoses were included. Both children with ADD/H (n = 16) and ADD/WO (n = 11) received significantly fewer "liked most" nominations, more "liked least" nominations, and lower social preference scores than normal control (n = 45) children. These results confirm previous findings of social deficits in children with ADD/H, even when codiagnoses are excluded. In addition, they support the validity of the diagnostic category of ADD/WO by demonstrating that the ADD/WO behavior pattern is apparently "psychopathological" in being associated with peer unpopularity after codiagnoses are excluded. When larger groups including all codiagnoses (primarily Conduct Disorder) of children with ADD/H (n = 36) and ADD/WO (n = 20) were compared, identical patterns of peer unpopularity were found, except that children with ADD/H also were significantly more likely to be nominated as a child who "fights most."

Attention↗
PubMed1987

Lateralized interference effects: evidence for a processing style by modality interaction.

A time-sharing paradigm was used to study potential interference effects of concurrent successive-auditory/vocal, successive-visual/motor, simultaneous-auditory/vocal, and simultaneous-visual/motor tasks on right- and left-handed manual-motor behaviors of differential levels of difficulty. Participants were selected from each of three developmental levels from 9 through 20 years of age. Results suggested that processing style (i.e., successive or simultaneous) interacts with modality (i.e., auditory/vocal or visual/motor) in terms of lateralized interference effects; however, potential effects due to age level were obfuscated by differential concurrent-task difficulties.

Adolescent↗
PubMed1987

Lateralization of visual hemifield attention across development.

Heilman and Valenstein (Clinical Neuropsychology, 1979, Oxford University Press, New York) have hypothesized a right hemispheric mechanism which mediates attention bilaterally. Shapiro and Hynd ("The development of functional lateralization in visual hemifield attention." Developmental Neuropsychology, Vol. 1, pp 67-80, 1985) examined the developmental validity of this model and their findings did not provide evidence for a lateralized mechanism for visual hemifield attention in 9, 13, and 18 year olds. However, length of foreperiod and gender effects were noted. This study attempted to compare these groups with a group of normal adults (ages 25-35) using the same reaction time paradigm. The study demonstrated support for the length of foreperiod effect found by Shapiro and Hynd. Hand effects were also found. However, these results do not lend support to either the model proposed by Heilman and Valenstein (1979) or Shapiro and Hynd's (1985) notion of developmental differences across age groups with respect to right hemisphere dominance for mediating attention.

Journal Article↗
PubMed1986

Visual-spatial orientation, gaze direction and dichotic listening asymmetries.

The effects of visual-spatial orientation on dichotic listening performance were investigated in a sample of right-handed male and female adults. The 30 pairs of dichotic stimuli (/ba/ka/da/ga/ta/pa) were presented under three conditions: eye gaze fixed toward center, eye gaze directed 20 degrees to the right, and eye gaze directed 20 degrees to the left of center. Although no effect for gender or order was evident, a significant right ear advantage was found under all conditions. However, over all dichotic listening accuracy was significantly increased when visual-spatial orientation was directed to the right or left side of space.

Adult↗
PubMed1986

Neurodevelopmental and racial differences in tactile-visual (cross-modal) discrimination in normal black and white children.

Controversy exists as to when those functions associated with the left tertiary cortex become fully developed in children. To address this issue, neuropsychological development of tactile-visual (cross-modal) discrimination was assessed in 200 normal children aged 5 through 9 years. The factors of gender and race (black, white) were evaluated across this age span. A three-factor ANOVA revealed no gender differences, but significant main effects for age and race existed. There were no significant interactions. White children outperformed black children across all ages, and Sheffe's post-hoc comparisons revealed that, by age 7, children have mastered those basic cross-modal functions necessary for complex higher cognitive processes. The implications of these findings are discussed.

Journal Article↗
PubMed1984

Dyslexia: two priorities for the 1980s.

Within the past decade significant advances have been made in articulating the unique neuropsychological and cognitive processes in dyslexic children. The brain mapping procedures and postmortum studies are especially important in this regard. However, two important issues remain largely unaddressed. First, to date, no recognized nosology for dyslexia or subtypes of dyslexia exist. Second, the functional neurolinguistic system involved in reading and severe reading failure is, as of yet, still not completely understood in regard to subtypes of dyslexia. This article discusses these two areas of priority and proposes a framework for addressing these areas of concern.

Brain↗
PubMed1983

Neuropsychological assessment of learning disabilities: a discriminant analysis.

The neuropsychological test scores of 23 learning disabled children were compared with those of a matched population of normal children in the 9-1 to 13-1 age range. All children were administered the Wechsler Intelligence Scale for Children-Revised (WISC-R), a dichotic listening task involving both free and directed recall conditions, a handedness inventory, the Tactile Performance Test and the Category Test from the Halstead-Reitan Neuropsychological Test Battery. A multivariate analysis of variance resulted in a significant separation between groups (p less than .001) using these procedures. A stepwise discriminant function analysis revealed that both of the directed dichotic tasks contributed the most of all 13 measures to the significant group separation. In addition, other cognitive tasks found to discriminate normal from learning disabled children include general verbal processes, concept formation, and tactile memory. These findings suggest that the directed dichotic listening procedure and the WISC-R Verbal IQ measure are reasonably valuable clinical tools in the classification of learning disabilities.

Adolescent↗
PubMed1983

Attentional deficit in learning-disabled children: evidence from visual half-field asymmetries.

The structural theory of cerebral lateralization has been typically used to explain hemispheric asymmetries. However, the attentional model of brain functioning may help resolve some of the inconsistent findings with groups of learning-disabled children. To test this hypothesis, a visual half-field paradigm for word recognition was employed in a group of 26 learning-disabled and 26 normal children matched for sex, chronological age, and handedness. Three experimental conditions (unilateral, cued unilateral, and bilateral) and two word error types (visually and acoustically confusable words) were analyzed. The results indicated that normals produced the expected RVHF superiority under all experimental conditions, but the learning-disabled produced the expected RVHF superiority only under the cued unilateral condition. Learning-disabled children also made significantly more visually and acoustically confusable errors than normals and unlike normal children increased the number of acoustic errors in the RVF under bilateral stimulation. These results provide evidence that learning-disabled children may process information inefficiently and have brain activation patterns that are more susceptible to attentional effects.

Adolescent↗