The interpolation of object and surface structure

One of the main theoretical challenges of vision science is to explain how the visual system interpolates missing structure. Two forms of visual completion have been distinguished on the basis of the phenomenological states that they induce. Modal completion refers to the formation of visible surfaces and/or contours in image regions where these properties are not specified locally. Amodal completion refers to the perceived unity of objects that are partially obscured by occluding surfaces. Although these two forms of completion elicit very different phenomenological states, it has been argued that a common mechanism underlies modal and amodal boundary and surface interpolation (the "identity hypothesis"; Kellman & Shipley, 1991; Kellman, 2001). Here, we provide new data, demonstrations, and theoretical principles that challenge this view. We show that modal boundary and surface completion processes exhibit a strong dependence on the prevailing luminance relationships of a scene, whereas amodal completion processes do not. We also demonstrate that the shape of interpolated contours can change when a figure undergoes a transition from a modal to an amodal appearance, in direct contrast to the identity hypothesis. We argue that these and previous results demonstrate that modal and amodal completion do not result from a common interpolation mechanism.     

Perceptual organization and White's illusion

The apparent lightness of a surface can be strongly modulated by the spatial context in which it is embedded. Early theories of such context dependence emphasized the role of low-level mechanisms that sense border contrast, whereas a number of recent authors have emphasized the role of perceptual organization in determining perceived lightness. One of the simplest and most theoretically challenging lightness illusions was described by White. This illusion has been explained with a variety of different models, ranging from low-level filter outputs to computations underlying the extraction of mid-level representations of surfaces. Here, I present a new method for determining the organizational forces that shape this illusion. I show that the spatial context of White's pattern not only transforms the apparent lightness of homogeneous target patches. but can also induce dramatic inversions of figure-ground relationships of textured target regions. These phenomena provide new evidence for the role of scission in causing the lightness illusion experienced in White's effect.     

Sexual activity among Zambian female teenagers: the role of interpersonal skills.

This study examined the relationship between interpersonal skills and sexual activity among female adolescents in Zambia. Data from 390 females in seven schools were analyzed. Results indicated that the inability to say no was associated with coital and noncoital sexual activity. The findings suggest that family planning programs should consider the role of interpersonal skills in controlling adolescent fertility.     

Reaction times, using fine and gross motor movements of moderately and severely mentally handicapped adults to auditory and visual stimuli

This experiment investigated the reaction times, when using fine and gross motor movements, of 24 moderately and severely mentally handicapped adults to light and sound stimuli. Unlike results of prior studies of normal and mildly mentally handicapped subjects, there were no significant differences among variables.     

The adaptation of black graduate students: A social network approach

Despite the importance of increasing the number of graduate degrees awarded to members of minority groups, there has been little research on how minority students adapt to the graduate school environment. The present study examined how social integration and social support were related to academic performance and psychological well-being among 89 black graduate and professional students. Findings indicate that black graduate students were not well integrated into their academic environment. Students in relatively more integrated departments were better adjusted, had higher grades, and perceived themselves to be making good progress in their graduate work. These students were also less likely to have considered dropping out of school. Frequency of out-of-school contact with black faculty and the number of black students in the department were important social integration and social support variables. The implications of these findings for minority student retention are discussed.     

MAINTENANCE OF THERAPEUTIC CHANGE BY MOMENTARY DRO

Differential reinforcement of other behavior (DRO) involves delivery of reinforcement at the end of an interval during which the target behavior has not occurred. Momentary DRO, however, is a procedure in which reinforcement is delivered if a response did not occur at the end of an interval. We examined the extent to which momentary DRO maintained suppression, following initial treatment with whole-interval DRO, of nine retarded students' maladaptive behavior. Results indicate that momentary DRO maintained response suppression comparable to that obtained by whole-interval DRO.     

Indonesia's Nurcholish Madjid and Abdurrahman Wahid as intellectual Ulama: The meeting of Islamic traditionalism and modernism in neo‐modernist thought

This paper examines two of Indonesia's leading Islamic intellectuals, Abdurrahman Wahid and Nurcholish Madjid, and the movement of thought with which they are associated, neo‐Modernism, a new movement in Islamic thought in Indonesia that emerged amidst much controversy in the early 1970s and has since been of considerable influence in the development of Islamic thought, particularly amongst younger Muslim intellectuals. The paper argues that this new movement of thought represents the coming together of Islamic traditionalism, Modernism and Western education in the persons of a generation of thinkers from traditionalist backgrounds, who as youths obtained a pesantren (traditional religious boarding school) religious education and then went on to undertake modern Western‐style, higher education. In doing this it focuses on the life experiences of two of the most outstanding thinkers to emerge from this generation: Nurcholish Madjid, a respected scholar and public figure and one of Indonesia's leading Islamic intellectuals, and Abdurrahman Wahid, currently serving his third term as chairman of Nahdlatul Ulama (NU), the leading traditionalist organization (and with a claimed support base of 35 million, Indonesia's largest Islamic organization).     

Inappropriate speech in a severely retarded child: a case study in language conditioning and generalization

The modification of inappropriate speech, a class of behaviors rather than a limited number of specific examples, is little known in the severely retarded. In this study, operant techniques were used to modify the strikingly bizarre and inappropriate speech of a severely retarded boy. The boy's appropriate verbal responses to questions about magazine pictures were reinforced with candy. When he responded inappropriately, the magazine was withdrawn, and social interaction was discontinued for a 10-sec timeout period. Negative responses were ignored, the next picture displayed, and the next question asked immediately. In 10 sessions, appropriate responses increased from 26% to 86% of all responses. A reversal of reinforcement was then introduced, in which inappropriate responses were reinforced, appropriate responses resulted in timeout, and negative responses were treated as before. This reduced the percentage of appropriate responses to 24%. Subsequent sessions of reinforcement for appropriate responses increased appropriate responses to 96% of all responses. At significant stages in the experiment, a measure of possible generalization was attempted. Although some generalization was recorded, it was minimal: some explanations are discussed.     

A COMPARISON OF TWO PROCEDURES FOR PROGRAMMING THE DIFFERENTIAL REINFORCEMENT OF OTHER BEHAVIORS

The relative effectiveness of two methods of programming DRO schedules of reinforcement was examined in two experiments. In these two methods, reinforcement is delivered if inappropriate responding is not occurring (a) at the end of an interval (momentary DRO), or (b) throughout the entire interval (whole-interval DRO). In Experiment 1, the effects of these schedules on disruptive responding of three retarded students were assessed in a multiple-baseline design. For two students, the momentary schedule occurred first and was ineffective, whereas the whole interval that followed was effective; for the third student, the whole-interval schedule occurred first and was effective, and reduced responding was maintained under the momentary schedule. In Experiment 2, baseline and the two DRO schedules were each presented in random order each day to one student in an alternating treatments design. The momentary DRO schedule reduced responding, but the whole-interval schedule was more effective.