3-D shape perception

In this paper, we analyze and test three theories of 3-D shape perception: (1) Helmholtzian theory, which assumes that perception of the shape of an object involves reconstructing Euclidean structure of the object (up to size scaling) from the object’s retinal image after taking into account the object’s orientation relative to the observer, (2) Gibsonian theory, which assumes that shape perception involves invariants (projective or affine) computed directly from the object’s retinal image, and (3) perspective invariants theory, which assumes that shape perception involves a new kind of invariants of perspective transformation. Predictions of these three theories were tested in four experiments. In the first experiment, we showed that reliable discrimination between a perspective and nonperspective image of a random polygon is possible even when information only about the contour of the image is present. In the second experiment, we showed that discrimination performance did not benefit from the presence of a textured surface, providing information about the 3-D orientation of the polygon, and that the subjects could not reliably discriminate between the 3-D orientation of the textured surface and that of a shape. In the third experiment, we compared discrimination for solid shapes that either had flat contours (cuboids) or did not have visible flat contours (cylinders). The discrimination was very reliable in the case of cuboids but not in the case of cylinders. In the fourth experiment, we tested the effectiveness of planar motion in perception of distances and showed that the discrimination threshold was large and similar to thresholds when other cues to 3-D orientation were used. All these results support perspective invariants as a model of 3-D shape perception.     

Lay theories of delinquency

This paper is concerned with the range, structure and determinants of lay people's implicit theories of delinquency. The different explicit psychological and sociological theories were reviewed as were studies on lay beliefs about crime and delinquency. After pilot interviews in which people were asked to list what they believed to be the major causes of delinquency, over 350 people completed a questionnaire in which they rated 30 explanations for their importance in explaining delinquency. The results showed numerous sex, age and voting differences. Conservatives tended to blame a person's poor education for his or her delinquency, while Labour voters tended to explain delinquency in terms of societal factors. A factor analysis revealed six clear explanation types for delinquency some of which were clearly related to explicit theories. Results were discussed in terms of the psychology of explanations and the relationship between explicit and implicit theories. Implications of this research were also noted.     

The good,the bad and the mad: Response bias in self-report measures

This study set out to examine the susceptibility of five extensively used, self-report measures to response set bias. Subjects were requested either to fake good, (give a good impression), fake bad, (give a bad impression), fake mad, (give an impression of mental instability) or respond honestly. Subjects who faked good had significantly higher Extraversion, Lie and Social Desirability scores but lowest Neuroticism, Psychoticism and Social Anxiety scores. Subjects who faked bad had significantly lower Extraversion and higher Psychoticism and Social Anxiety scores. Fake mad subjects scored higher on Self-Monitoring and Locus of Control. Four of the eight scales showed significant differences between subjects faking bad and those faking mad. The results are discussed in terms of questionnaire design and respondent's motivation.     

An empirical typology of violent incidents reported by prison inmates with convictions for violence

Forty-four male prison inmates convicted for violent offences were interviewed, and details of current offence, previous convictions for violence, prison incidents, and violent situations outside of prison were obtained from each offender. Information on victim, circumstances, precipitating events, type of violence, emotions at the time, and the like, was derived for 246 violent incidents. Cluster analysis revealed eight clusters: “criminal” violence to familiar victims, peer violence within prison, domestic violence, peer violence in pubs, gang violence, violence to staff in prison, “criminal” violence to unknown victims with accomplices, and public violence against younger victims. Results were discussed in terms of treatment of violent offenders, with special emphasis on Social Skills Training.     

Editorial: Shaping Ethical Futures in Brain-Based and Artificial Intelligence Research

Science and Engineering Ethics -     

Memory for action events: findings in neurological patients

Encoding action phrases by enacting leads normally to better memory performance than verbal encoding. In order to gain additional insight into the representational basis of the enactment effect, neurological patients are contrasted with healthy participants. Persons suffering from Parkinson's disease, which primarily impairs the motor system, and patients suffering from Frontal Lobe Syndrome, which primarily affects action-related planning processes, were involved. We investigated whether the enactment effect would be differentially affected by these disorders. In addition, the characteristics of information processing after encoding by enacting was analyzed by varying memory material (unrelated versus clusterable actions) and by adding an encoding condition that included obligatory action planning (director condition). The findings indicate that the impact of motor information for the enactment effect is not dominant compared to the role of action-related cognitive and motivational processes, in particular planning processes. The findings of the two experiments are explained within traditional conceptual memory theories.     

Emotion-induced amnesia in rats: working memory-specific impairment, corticosterone-memory correlation, and fear versus arousal effects on memory

We have shown previously that psychological stress (predator exposure) impairs spatial memory in rats. We have extended that finding here to show that predator stress selectively impaired recently acquired (hippocampal-dependent) spatial working memory without affecting long-term (hippocampal-independent) spatial reference memory. We also investigated why predator exposure impairs memory. Was spatial memory impaired because of the fear-provoking aspects of predator exposure or only because the cat was a novel and arousing stimulus? If the latter possibility was correct, then any novel and arousing stimulus, independent of its emotional valence (i.e., aversive or appetitive), would impair memory. We found that spatial working memory was not impaired when the male rats were exposed to a sexually receptive female rat, a stimulus that was novel and arousing to them, but not aversive. We also found that there was an equivalent increase in serum corticosterone levels in male rats exposed to either a cat or a female rat, but only the cat-exposed rats exhibited a significant correlation between corticosterone levels and impaired memory. Overall, this series of experiments demonstrates that (1). predator stress selectively impaired working (hippocampal-dependent), but not reference (hippocampal-independent), memory; (2). a fear-provoking stimulus, and not merely novelty and increased arousal, impaired spatial memory; and (3). increased corticosterone levels correlated with impaired spatial working memory only under predator exposure, that is, fear-provoking conditions.