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J Stiles

Publications and source records attributed to J Stiles.

43 records · Page 3Linked to original sources
PubMed1991

Spatial grouping activity in young children with congenital right or left hemisphere brain injury.

Spatial grouping abilities were examined in 20 preschool-aged children with right or left hemisphere congenital focal brain injury, and a group of age-matched normal control children. Children were presented with a series of spontaneous grouping tasks in which they were given small sets of blocks and asked to play with them. Although the children with focal brain injury played as actively with the blocks as normal children, the constructions they produced differed systematically. Across eight measures of spatial grouping both children with right and left hemisphere injury were delayed compared to normal children. In addition, the behavioral profiles for the two groups of children with focal brain injury were qualitatively different. Data for the children with RH injury suggested difficulty organizing objects into coherent spatial groupings, while data from the children with LH injury suggested difficulty with local relations within the spatial arrays. These findings are consistent with data reported for adults on spatial construction tasks. Developmental trajectories in the 3- to 4-year age period suggest, further, that the spatial integrative deficits observed in the children with RH injury are persistent. When the children began to produce spatial constructions using complex grouping procedures, those constructions were heaps or disordered clusters. In contrast, when children with LH injury began to use complex procedures, they generated the types of constructions usually associated with those procedures in normal children, e.g., arches, enclosures, and symmetries. These data were found within a cross-sectional study of 20 children and confirmed in a series of six longitudinal case study reports of three children with RH and three with LH injury. The data confirm our previous reports of spatial integrative deficit associated with early RH injury and present the first indication of spatial encoding deficits in children with LH injury.

Age Factors↗
PubMed1991

Global-local processing in preschool children.

The tendency of young children to attend to global and/or local levels of hierarchically structured patterns was examined using an orientation judgment task. 3- and 4-year-old children and adults were asked to judge which way an equilateral triangle was pointing under different contextual conditions. In Experiment 1, contextual variations included overall pattern orientation, configuration alignment type, presence or absence of an immediate frame of reference, and type of local element context. The results showed that, contrary to previous reports in the literature, young children, like adults, attend to both global and local levels of a pattern. Both pattern orientation and the introduction of contextual cues affected children's judgments, and the magnitude of that effect varied with the particular contextual cue present in the stimulus array. In Experiment 2, contextual variations included overall pattern orientation and presence or absence of an internal local level element. Consistent with the results of Experiment 1, young children's orientation judgements were influenced by the addition of local level factors.

Attention↗
PubMed1990

Facilitative effects of labeling on preschool children's copying of simple geometric forms.

A total of 150 children between 2.5 and 5 yr. of age were tested on one of three conditions (one experimental and two control) of a copying task adapted from the 1982 Developmental Test of Visual Motor Integration of Beery. In the experimental condition, the geometric forms were labeled with the names of familiar objects. Analysis of scores indicated that introduction of verbal labels on the copying task facilitated preschool children's ability to reproduce geometric forms. The effect was consistent across the ages tested but was limited in that facilitation was observed only for those forms just beyond the child's demonstrated level of mastery. These results suggested that the verbal labels evoked a representational context which provided children with additional information necessary for accurate reproduction of the forms. Two alternative interpretations of this finding are discussed.

Child, Preschool↗
PubMed1988

Age-related morphometric differences in responses of rat lungs to ozone.

The influence of age on morphologic changes in lungs of rats exposed to ozone was studied in female Sprague-Dawley rats, aged 60 and 444 days. Rats of both age groups were exposed continuously for 72 hr to either 0.35 or 0.80 ppm ozone, or to filtered air. Tissues were evaluated using light microscopic morphometry and scanning electron microscopy. The lungs from ozone-exposed 60-day-old rats had larger volume fractions of centriacinar lesions than lungs from exposed 444-day-old rats. Within each age group there was an observed dose response, with rats exposed to 0.80 ppm ozone having larger volume fractions of lesions than those exposed to 0.35 ppm. Only the 444-day-old rats lost body weight during the exposure period. They also had smaller fixed lung volumes than same-aged controls. All 60-day-old rats gained weight during the exposure period, although rats exposed to 0.80 ppm ozone gained less than filtered air controls. Lesions observed in both age groups of female rats were qualitatively similar to those previously described in young adult male rats. We conclude that there are age-related differences in the morphometric responses of rats to ozone exposure. Younger rats had larger proportions of centriacinar lesions and macrophages while older rats had greater body weight and lung volume changes.

Aging↗
PubMed1980

Influence of time after ensiling on distribution of nitrogen in corn silage treated with ammonia.

Chopped whole corn plant was treated before ensiling with 1.4% ammonia (of dry matter) to which .36% atom excess of 15N had been added. About 50 kg of material (14 kg dry matter) were placed in .5-mm polyethylene bags (of double thickness) which were evacuated and served as experimental silos. Silage samples were taken on days 0, 3, 7, 14, 21 and 50 and analyzed for N fractions. The 15N content of these fractions was analyzed by a mass spectrophotometer. N fractions of untreated silage were also determined. Between days 0 and 7 of fermentation, ammonia N decreased from 50 to 39% of the total silage N, with a corresponding increase in nonammonia N, from 50 to 60%. Thereafter, little change was noted in these fractions. Approximately 40% of the increase in non-ammonia N was in the soluble portion and 60% was in the insoluble portion. Insoluble N of treated silage was 50% higher than that of control silage. Initially, 89% of the N from added ammonia was recovered as ammonia, but this proportion decreased to 68% by day 7 and changed little thereafter. There was immediate incorporation of 43% of the ammonia into the insoluble N fraction. Most of the initial binding was as intact ammonia, with a subsequent release during fermentation. Because direct ammonia incorporation accounted for a higher percentage of the insoluble N increase on day 0 than on subsequent days, these data support earlier studies which showed that ammonia decreased breakdown of protein of the ensiled corn plant.

Ammonia↗