人类颜色视觉的计算理论

该文有机地结合了计算视觉理论和生态学视觉理论,指出颜色信息处理的根本任务是检测环境中的光不变量。在此基础上,作者提出了颜色视觉的计算理论以及计算理论本身的生物学标准。初级视觉计算是典型的不适定问题,动物的视觉系统则利用视环境中存在的条件将该不适定问题转化为定解问题。本文引入颜色视觉计算的免要条件,客观性约束,以及颜色认知的神经表象,证明了上述约束下颜色算法的存在性。本文给出了构造颜色知觉的基本假设。同时,该文还讨论了与上述问题密切相关的几个基本问题:神经表象的完备性,主观色觉的客观性,明度知觉和颜色知觉的统一,人类主观色觉的实现方式。     

Consultation Contracts

Consultants enter into legal contracts each time they agree to a consultation arrangement outside of their regular work setting. They need to understand the legal context of contracts within which they perform their services and recognize the benefits a written agreement provides. Counselors often provide consultation services as a regular part of their job responsibilities. In such situations, a separate legal contract is not formed when a consultation relationship is created. A written understanding of the consultation arrangement, however, can be beneficial to the consultant and consultee even though a legal contract does not exist.     

HIV Disease: Current Concepts

The human immunodeficiency virus (HIV) causes a chronic, progressive, immune deficiency disease, the most severe phase of which is Acquired Immune Deficiency Syndrome (AIDS). HIV is a newly characterized human retrovirus transmitted only by direct exposure to blood or blood derivatives, certain acts of sexual intercourse, or transfer from infected mother to fetus or infant. In this article the author reviews the most important current epidemiologic, clinical, and virologic information about HIV and HIV disease and provides a factual framework for understanding the issues created by the epidemic.     

Assessing Adolescent and Adult Attachment: A Review of Current Self-Report Measures

Increased interest in attachment theory among counseling researchers and practitioners has led to the development of several measures of attachment-related constructs. Following a brief overview of the theoretical foundations of attachment theory as conceptualized by Ainsworth (1989) and Bowlby (1988), the authors of this article review four self-report measures of adolescent and adult attachment. Many considerations for the selection and use of these instruments in future counseling research and assessment are discussed.     

Contextual effects on the ability of divers to use decompression tables

The present study compared the ability of novice divers to apply decompression tables having learnt how to use them in either the same or a different environment. Those subjects who had learnt how to use the tables in a different environment (i. e. had learnt on dry land and were tested underwater or vice-versa) performed on average 64 percent worse than those who had the same environment for both learning and test. This effect could not be ascribed to the disruption brought about by changing environments. The results show that contextual effects on memory extend beyond the recall of word lists (Godden and Baddeley, 1975) to the ability to implement potentially important instructions.     

Interrelationships among students' study activities,self-concept of academic ability,and achievement as a function of characteristics of high-school biology courses

This investigation focused on the interrelationships among students' study activities, students' self-concept of academic ability ratings, students' academic achievement, and instructional practices in 12 high school biology courses. Using a framework derived from a previous investigation, course features were classified into those that appear to (a) place demands on, (b) support, or (c) compensate for student engagement in particular study activities. Students' study activities, self-concept of academic ability ratings, and achievement were measured with experimenter-developed instruments. Results are reported for (a) characteristics of instruments and course features, (b) relationships between central factors of the investigation, and (c) multi-level relationships between course features and student variables. Results at the student level indicated that self-concept of academic ability and, to a lesser extent, students' study activities were positively associated with student achievement. Students' self-concept of academic ability ratings were also linked to students' engagement in generative, proactive study activities. At the course level the supportive practices of providing challenging homework assignments and extensive feedback on student coursework were associated with student engagement in effortful, generative, proactive study activities. The provision of extensive feedback was also associated with high student achievement. Multi-level relationships were analysed using hierarchical linear modelling (HLM) analyses. These analyses revealed, for example, that in courses in which little or no feedback is given on homework assignments, the relationship between achievement and student engagement in diligent effort management activities was enhanced. Other HLM analyses were conducted to examine the mediating role of course features on the relationship between students' self-concept of academic ability and their study activities and achievement. For example, the presence of challenging course demands was associated with an enhancement of the relationship between self-concept of academic ability and achievement whereas the presence of instructor provisions (supports and compensations) designed to reduce course demands was associated with a reduction in this relationship.     

Predictors of stress in adolescents: an exploratory study of pregnant and of parenting females

A study of 152 adolescents enrolled in school-based programs for pregnant and parenting youth in Colorado in 1987-88 found no differences in overall stress levels between these two groups; however, salient predictors of stressful life events for pregnant teens were not the same as those for teen mothers. The mean age of study subjects was 16.5 years (range 14-19 years); most were living with a parent rather than the child's father. The dependent variable, level of stress, was measured through use of an abbreviated Life Events Questionnaire. Independent variables were assessed through administration of the Inventory of Social Supportive Behaviors, Rosenberg Self-Esteem Scale, and the Adolescent Coping Orientation for Problem Experiences scale. Of the 5 sources of stress measured (family, accidents, autonomy, deviance, relocation, and distress), only stress related to accidents differed significantly between pregnant and parenting adolescents. For pregnant adolescents, self-esteem was the only significant predictor of the overall level of stress; among parents, the only significant predictor was objective social support. Among adolescents, self-esteem was associated with more frequent use of social support and coping strategies. For parenting adolescents, self-esteem was correlated with the frequency of use of social support, satisfaction resulting from such use, and frequent use of coping strategies. Overall, the independent variables of social support, self-esteem, coping, and age were stronger predictors of stress in pregnant than in parenting adolescent females. This finding suggests that parenting teens may have successfully negotiated the multiple transitions involved in this new stage of the life-cycle. An important implication of this study is the need to design separate counseling components of school-based programs for pregnant versus parenting adolescents rather than to use a single curriculum.     

An alternative procedure for analyzing job analysis results for content-oriented test development

Content-oriented test development requires information derived from a comprehensive job analysis. The job data typically consist of task and skill statements identified by subject matter experts. These statements characterize a target job and are then used to develop the test plan and item budget. The predominant practice for combining data from the task and job skill domains to facilitate preparation of a test plan and item budget is an impressionistic approach. This study reports variations and extensions of an alternative quantitative procedure for linking task and job skill data (Hughes & Prien, 1989) using results obtained in field studies. The results indicate that the procedure reported by Hughes and Prien (1989) yields consistent results. Also, modifications to the procedure result in more detailed solutions.Dr. Charles Lawshe graciously contributed three sets of job analysis data to this research project. Dr. Lawshe also provided a very thoughtful and cogent critique of our attempts to express these thoughts to a user audience and for this we are grateful.