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THE EMERGENCE OF CHILDREN'S SPATIAL ABILITIES: A QUESTION OF GEOMETRIC PRECISION.
This research investigated the precision with which spatial information can be maintained in memory and reproduced as well as factors which may effect these emerging abilities. To study this, ten males and ten females in each of first, third, fifth, and seventh grades participated in three drawing tasks under two conditions (match and recall). The tasks involved the presentation of a 4" straight line or a 2" x 2" right angle drawn on an 8" white disc. Subjects were asked to draw a line exactly the same size and in the same place (static), after an imagined rotation, or after an imagined bending or unbending of the line (transformation) on an 1" white disc. Several mixed design analyses of variance with repeated measures on the task variables were run. First graders made significantly more errors than all other subjects. Third and fifth graders differed little and both performed significantly less accurately than seventh graders. Performance on the rotation task and the transformation task did not differ significantly with performance on both yielding more error than performance on the static task. The match condition generally proved easier than the recall condition, straight lines led to less error than bent lines, and orientation information was more accurately preserved than metric information. The requirements of the task, i.e., no change, change in position, or a change in form, interacted with both the stimulus type and the type of information preserved. Grade level also interacted significantly with task and stimulus type. When determining how spatial abilities emerge and the accuracy with which spatial information can be dealt, task demands, stimulus characteristics, and type of information being measured must be considered along with the developmental changes
Crack Use and Correlates of Use in a National Population of Street Heroin Usersâ€
Traditionally, researchers and clinicians have viewed street heroin users as representing an end point in a drug-using career. It is toward this population that major national treatment efforts have been directed. Concomitant with the historical national concern about heroin use has been concern about the increase in crack cocaine use. There has been speculation that crack use may have become a substitute for the higher risk of heroin injection. This article examines the impact of crack use in a national population of heroin users. It was consistently found that there was a correlation between the frequency of crack use and the frequency of speedballing as well as the use of other forms of cocaine, amphetamines, and marijuana. There was also a positive relationship between frequency of crack use and such HIV risk behaviors as renting needles and having a large number of sex partners. The data suggest that in this population of heroin users, crack is not a substitute for heroin but rather is a part of a drug-use pattern that includes an increased use of other drugs and increased high-risk behaviors for contracting HIV. © 1992 Taylor & Francis Group, LLC