Search behavior in various breeds of adult dogs (Canis familiaris): object permanence and olfactory cues.

Human analog tests of object permanence were administered to various breeds of adult dogs (Canis familiaris). Experiment 1 showed that the performance of terriers, sporting, and working dogs did not differ. Dogs succeeded in solving invisible displacement problems, but performance was lower than in visible displacement tests. Familiarity with the task had some influence because invisible displacement tests were more successful if they were preceded by visible displacement tests. In Experiment 2, odor cues from the target object and the hiding screens were available or were masked. Results confirmed that success was lower in invisible than in visible displacement tests and that these problems were solved on the basis of representation of visual information rather than on the basis of olfactory cues or of local rule learning. Dogs are compared with other species that display Stage 6 object permanence.     

Is anorexia nervosa a neuropsychological disease?

Evidence for central nervous system, and more particularly cortical, etiology of anorexia nervosa is reviewed. Topics covered are neuropsychiatric comorbidity, inheritance patterns, the neurobiology of body-image disturbance and of the eating function, perinatal and alcoholic insult to the brain, neurochemical and neuroelectric disturbance, anatomic and metabolic brain imaging, and neuropsychological impairment. It is concluded that there is indeed an important neuropsychological etiological dimension to anorexia nervosa. The profile most frequently associated with anorexia nervosa is right posterior hypometabolism, followed by right anterior hypermetabolism, both associated with right-sided abnormal electroencephalogram spiking. It is also proposed that bulimia consists of a positive neurological subtype and that restricting anorexia represents a negative neurological subtype. Priorities for further research into anorexia nervosa are specified to include twin adoption studies, brain electrical topography studies, postmortem histological studies, and experimentally inspired neuropsychological studies.     

Subjective contours 1900–1990: Research trends and bibliography

Abibliography on subjective contours and a brief summary of trends in research-on-thin problem are presented. The bibliography covers the years 1900–1990 and contains 445 entries, each briefly annotated with a code that indicates the general content and theoretical orientation of the item.     

Visual perception of surface curvature: psychophysics of curvature detection induced by motion parallax

The continuous approach to optic-flow processing shows that the curvature of a moving surface is related to a second spatial derivative of the velocity field, the spin variation (Droulez & Cornilleau-Pérès, 1989). With this approach as a theoretical framework, visual sensitivity to the curvature of a cylinder in motion was measured using a task of discrimination between cylindrical and planar patches. The results confirm the predictions suggested by the theory: (1) Sensitivity to curvature was always greater when the cylinder axis and the frontal translation were parallel than when they were orthogonal. The ratio of curvature detection thresholds in the two cases was between 1.3 and 2.5; the value predicted from the spin variation theory is about 2. (2) Sensitivity to curvature increased strongly with the velocity of the motion but was only weakly affected by its amplitude and the duration of viewing for the range of values used in our experiments.     

Using item-specific instructional information in achievement modeling

The problem of detecting instructional sensitivity (item basis) in test items is considered. An illustration is given which shows that for tests with many biased items, traditional item bias detection schemes give a very poor assessment of bias. A new method is proposed instead. This method extends item response theory (IRT) by including item-specific auxiliary measurement information related to opportunity-to-learn. Item-specific variation in measurement relations across students with varying opportunity-to-learn is allowed for.This paper was presented at the 1987 AERA meeting in Washington, DC. This research was supported by grant OERI-G-86-003 from the Office of Educational Research and Improvement, Department of Education. The author thanks Michael Hollis and Chih-fen Kao for valuable research assistance, and appreciates valuable comments made by an anonymous reviewer.     

Factor structure in groups selected on observed scores

A new method is proposed for estimating factor means and factor covariances in a group of individuals selected on their observed scores. The selection variable is, for example, the total score on an admissions test. Given a factor model for the test items based on the group of test takers, we may be interested in the factor structure for those in the top quartile. The differences in factor means and covariances between this selected group and the full group gives useful information both on successful test performance and on test validity. The new method draws on the classic Pearson-Lawley selection formulas. It avoids the fallacy of factor analysis on the selected group, which would lead to incorrect estimates. The new method is applied to a simple factor structure model for the GMAT test. Although the majority of the GMAT items test verbal skills, it is found that a quantitative factor shows the greatest change in moving from average to top quartile test takers.     

STRATÉGIES COGNITIVES ET PROCESSUS D'AUTORÉGULATION CHEZ DES FAMILLES EN SITUATION DE RÉSOLUTION DE PROBLÈMES LOGIQUES*

The family is a fundamental learning environment for many basic skills such as the ability to solve everyday domestic problems. A lack of competence in this type of problem solving would expose the individual to more frustration and possibly create the conditions for greater aggression. Forty-two low SES families, each including an aggressive boy, were invited to the laboratory for a problem-solving session on two occasions, at an interval of two years. Subjects were asked to find four preset combinations of colours by systematic permutations of four colours using a computer. Three types of cognitive performance were examined: resolution strategies, autoregulation strategies and the success rate in finding the solution. Results showed that most of the families were consistent in their use of a non-systematic strategy. Although some improvement in planning is observed during the second testing, no other improvement in autoregulation strategies was observed. In general, families had a better rate of success in finding the solution in the second session. The low cognitive level of these families and its stability are discussed. Étant donné que la famille constitue un terrain privilégié d'apprentissage, l'aggressivité comportementale de certains enfants pourrait résider dans le peu d'opportunités offertes par leur famille d'apprendre à affronter les problèmes de la vie quotidienne d'une manière réfléchie. Quarante-deux familles de milieu socio-économique faible, dont un des enfants est à risque d'inadaptation sociale et dont les parents sont peu scolarisés, ont à résoudre un problème nécessitant l'intelligence logique et ce, à deux ans d'intervalle (T-1 et T-2). La tâche consite à résoudre un problème de permutations à quatre éléments et se présente sous la forme d'un jeu d'ordinateur. Le fonctionnement cognitif est examiné selon trois dimensions: les stratégies cognitivcs de résolution, les stratégies d'autorégulation exercées, sur la démarche cognitive et l'issue de la démarche cognitive. L'examen des stratégies cognitives révèle que la majorité des familles utilisent une approche non stratégique et que cette approche est maintenue aussi bien à l'intérieur d'une séance donnée que d'une séance à l'autre. Exception faite de l'amélioration relevée à la séance 2 quant au contrôle exercé par les familles sur le déroulement de leur démarche cognitive, aucun changement n'émerge sur les autres critères de l'autorégulation. Finalement, les familles obtiennent une meilleure performance à la deuxième séance. La discussion porte sur la relative stabilité du niveau de fonctionnement cognitif des familles ainsi que sur la pauvreté apparente de leur répertoire de schèmes.     

The Effects of Clothing and Dyad Sex Composition on Perceptions of Sexual Intent: Do Women and Men Evaluate These Cues Differently1

The effects of clothing revealingness and dyad-sex composition on perceptions of male- and female-stimulus persons' sexuality were examined. Based on Abbey's (1982) findings, we hypothesized that men would attribute more sexuality to both male and female targets than women would. Furthermore, we predicted that the difference between men's and women's sexuality ratings would be most divergent when a male-female dyad was presented and when the female stimulus person wore revealing clothing. A laboratory study was conducted in which subjects viewed a photograph of two students in a classroom. As predicted, male subjects rated female targets as more sexy and seductive than did female subjects. Also as predicted, female targets who wore revealing clothing were rated as more sexy and seductive than those wearing nonrevealing clothing. Female targets were rated higher on sexual traits regardless of the gender of their partner. Men did not consistently perceive male stimulus persons more sexually than women did. Finally, both female and male targets were perceived as more kind and warm when they wore nonrevealing clothing. The implications of these findings for person perception and date rape research are described.