Favorable treatment outcome for drug abuse was about two to three times more likely if treatment was completed. Also, there were no outcome differences between residential and outpatient groups. Alcohol was the most common drug used during the follow-up period, despite cannabis being the preferred drug at intake.

Five-and 7-month-old infants were tested for sensitivity to the depth cue of shading. Infants were presented with two displays: a surface in which a convexity and a concavity were molded and a photograph in which shading specified a convexity and a concavity. Each display was presented under both monocular and binocular viewing conditions. Reaching was observed as the dependent measure. Infants in both age groups reached preferentially for the actual convexity in both the monocular and binocular viewing conditions. In the monocular photograph condition, the 7-month-olds reached preferentially for the apparent convexity specified by shading, indicating that they perceived it to be an actual convexity. These infants showed no significant reaching preference in the binocular photograph condition. This finding rules out interpretations of the infants' reaching not based on perceived depth. The results therefore suggest that the 7-month-olds perceived depth from shading. The 5-month-olds showed no significant reaching preferences when viewing the photograph; thus, they showed no evidence of depth perception from shading. These findings are consistent with the results of a number of studies that have investigated infants' sensitivity to pictorial depth cues. Together, these studies suggest that the ability to perceive depth from pictorial cues may first develop between 5 and 7 months of age.Shading, variation in luminance in the retinal image, provides an effective source of visual information for the three-dimensional shapes of objects. Shading can create compelling impressions of three-dimensionality in paintings and photographs, and can specify the shapes of objects in natural environments. Shading provides information for three-dimensional shape because of the lawful relationship that exists between the orientation of a surface and luminance in the retinal image projected by the surface (Gibson, 1950). A surface will reflect more light when it is oriented orthogonally to the source of illumination than when it is oblique to the incident light. As a result, if illumination does not vary and if a surface is uniform in reflectance, gradients of luminance in the retinal image correspond to changes in the surface's orientation and, therefore, can specify three-dimensional object shape.Perceiving shape from shading, however, involves a formidable problem for the visual system. Shading is potentially ambiguous because information for shape, or surface orientation, is confounded in the luminance values in the retinal image. The luminance of any point in the

This exploratory study examined gender differences among drug-abusing adolescents (N = 2,281). Overall, male adolescents reported somewhat higher usage levels of various drugs than did female adolescents, and they had an earlier onset of regular marijuana use. In terms of clinical signs of problem severity, female adolescents showed higher scores than male adolescents on Physical Symptoms, Escape (with drugs), and Emotional Consequences (of drug use) scales when drug use levels were controlled. However, the relatively small magnitude of the significant differences, and the fact that many scales did not show group differences, suggest that male and female adolescents attending drug clinics share many similar features of adolescent drug abuse. Implications of these findings for the prevention and treatment of adolescent drug abuse are discussed.

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