THE VISUAL SYSTEM'S MEASUREMENT OF INVARIANTS NEED NOT ITSELF BE INVARIANT

Abstract— When two shapes that differ in orientation or size have to be compared or objects have to be recognized from different viewpoints, the response time and error rate art systematically affected by the size of the geometric difference. In this report, we argue that these effects are not necessarily solid evidence for the use of mental transformations and against the use of invariants by the visual system. We report an experiment in which observers were asked to give affine-invariant coordinates of a point located in an affine frame defined by three other points. The angle subtended by the coordinate axes and the ratio of the lengths of their unit vectors systematically affected the measurement errors. This finding demonstrates that the visual system's measurement of invariants need not itself be invariant.     

The PsyCLE project: Developing a psychology computer-based learning environment

PsyCLE is a 3-year project involving over 30 United Kingdom universities to develop multimedia resources for introductory psychology courses. Our goal is to support active learning and encourage students to form a sound understanding of concepts under study. The developments focus on interactive tasks, illustrative case study material, and tools to support critical thinking and analysis. We discuss the rationale for the approach adopted and describe the developed resources and their evaluation and use.     

Stress,coping resources,and injury risk

Over the last two and a half decades, researchers have tried to determine if psychological variables predispose or buffer athletes from injury. They have found that sport participants who experience many recent stressors, and who do not have the resources and skills to cope with the stress, seem most at risk for injury. This article reviews that research as well as efforts to identify mechanisms that might explain why the stress-injury relationship occurs and interventions that will hopefully reduce the injury risk. Because the multicomponent stress-injury model of Andersen and Williams (1988) helped provide the impetus and theoretical base for much of that research, it serves as the foundation for organizing and summarizing the findings. Although the research has focused largely on sport injuries, the findings have relevance for understanding and potentially preventing many accidents and injuries that occur outside the realm of sport participation.     

Stop—reaction time and the internal clock

In astop-reaction-time (stop-RT) task, a subject is presented with a regular, isochronous sequence of brief signals separated by a constant time interval, orstimulus onset asynchrony (SOA). His/her task is to press a response key as fast as possible when the sequence stops. As the sequence unfolds, an internal representation of the SOA duration builds up. Stop-RT is assumed to be triggered when aninternal clock, operating as an “alarm clock,” reaches a time criterion. Criterion setting is contingent upon variability in the SOA’s internal representation. In Experiment 1A, stop-RT was measured for isochronous sequences of brief tones, light flashes, and also sequences of tones and flashes presented in regular alternation (tone-light-tone…). Stop-RT was a linear function of SOA duration (ranging from 250 to 1,000 msec), regardless of modality, supporting a “central-clock” hypothesis. On the other hand, taken together, the results of Experiments 1A, 1B, 2, and 3 suggest that no internal representation of thebimodal (tone-light) SOA of alternating sequences builds up. Indeed, an alternating sequence is physically equivalent to two interlaced isochronous subsequences, one auditory and one visual. So,two internal representations, one for the auditory (tone-tone) and one for the visual (light-light) SOA, could build up, andtwo time criteria running “in parallel” could thus support stop-RT. To provide a critical test of parallel timing, stop-RT was measured for bimodal 5∶3 polyrhythms formed by the superposition of auditory and visual isochronous sequences that haddifferent SOA durations (Experiment 4). Parallel timing accounted for a large proportion of variance in polyrhythmic stop-RT data. Overall findings can be accounted for by assuming a functional architecture of an internal clock in which pulses emitted by acentral pacemaker are available in parallel with twomodality-specific switch-accumulator “timing modules.”     

Une contribution Sovietique essentielle au debat sur l'unite de la geographie

Sans résumé     

Social interactions among teachers, handicapped children, and nonhandicapped children in a mainstreamed preschool

The emotional tone and social integration of two mainstreamed preschool classes were studied to determine whether or not the findings of an earlier study would be repeated. Although most variables showed no differences between handicapped and nonhandicapped children's peer-directed and teacher-directed behaviors, result did suggest that, particularly in one class, nonhandicapped children tended to selectively interact with other nonhandicapped (as opposed to handicapped) children when engaging in more complex (associative) social play. Handicapped children did not show the same tendency to interact more within their own group. At the same time, handicapped children received more help and affection from peers, and were more effectionate towards peers, than nonhandicapped children. Teachers refused handicapped children's requests and corrected their behavior more often; however they also gave them more help and more affection than nonhandicapped children. The results were generally congruent with those of an earlier study but did show more segregation on the part of nonhandicapped children.     

Sexual preference,feminism, and women's perceptions of their parents

In an attempt to clarify the relation between parental variables, sexual preference, and sex-role attitudes, three groups of women were studied: lesbian feminists, heterosexual feminists, and heterosexual traditional women. The women were asked about their perceptions of their parents when they were in high school. The groups differed more from each other with respect to their perceptions of their fathers than their mothers. The perceived attitudes of the father were much more important in differentiating lesbian feminists from heterosexuals than in differentiating heterosexual feminists from heterosexual traditionals. Both the heterosexual groups (feminist and traditionals) reported having a more affectionate and involved father who also encouraged them more in the expression of anger than the lesbian feminists reported. The results suggest women's father relationships must not be obscured in research and support Johnson's hypothesis that the father relationship is more central than the mother relationship in sex typing and especially in the specifically sexual aspects of sex typing.     

Stress,coping, and life change in the single-parent family

Self-perceived competence in three roles (parent, social participant, self-supporter) was examined in relation to life satisfaction in a sample of 47 divorced, employed, single parent, middle-income women. Parenting was found to be the role of greatest perceived competence, and self-supporter the role of lowest perceived competence. Competence as a self-supporter was the strongest predictor of life satisfaction. Life satisfaction did not differ significantly between groups defined by length of time as single parents. For women separated less than 3 years, the social participant was the role of least perceived competence and the best predictor of life satisfaction. For those separated more than 3 years, the three roles were nearly equal in perceived competence, but competence as self-supporter was the best predictor of life satisfaction.     

Smoking cessation with behaviour therapy or acupuncture—A controlled study

Five hundred and fifty-eight cigarette smokers (mean 31 cigarettes/day) were randomized in four groups: Acupuncture, Behaviour Therapy, Placebo Medication and Waiting-list Control. The life-table analysis of smoking cessation showed, at a 12-month follow-up, no difference between Acupuncture, Behaviour Therapy and Placebo. Differences appeared only in an analysis of the abstinent subjects at each data point. Behaviour Therapy and Acupuncture accounted for significantly more abstinent subjects than Placebo at the end of the 2-week therapeutic phase. However at 9 and 12 months Acupuncture had a statistically-significant greater number of abstinent subjects than Behaviour Therapy, but there was no difference between Acupuncture and Placebo. The percentage decrease in smoking from baseline appeared significantly greater at 12 months in the first three groups than in the Control conditions. However, as in most smoking-cessation studies, the overall effect was small and non-specific. The results reflect the importance of maintenance programmes and of the prevention of addiction.