Position of the Egocentric Reference and Directional Arm Movements in Right-Brain-Damaged Patients

We asked 12 right-brain-damaged patients (6 with left neglect signs and 6 without left neglect signs) to perform a straight ahead pointing task and a visual detection task with lateralized motor response, in order to investigate the relationship between the position of the egocentric reference and response time and accuracy in producing lateralized arm movements. Results showed that there was no correlation between the position of the egocentric reference and neglect signs, nor between the position of the egocentric reference and the latencies to direct a motor response toward either side of space. These findings were interpreted within the context of egocentric hypotheses of neglect. In particular, it was suggested that attentional or intentional neglect signs cannot be considered as a direct consequence of an ipsilesional deviation of the egocentric reference.     

Mental representation and hypothetico-deductive reasoning: The case of the THOG problem

Summary This article reports three experiments that deal with the source of the difficulty of Wason's (1977) THOG problem. The solution of this problem demands both the postulation of hypotheses and a combinatorial analysis of their consequences. Experiment 1 showed that the generation of the hypotheses is not in itself sufficient to solve the problem. Experiment 2 showed that a version presenting a plausible context for separating the level of data from that of hypotheses produced a better performance than both the original abstract version and a thematic version lacking the plausible context separating the levels. Experiment 3 gave evidence that this context can produce facilitation even with the geometric material of the classic version. This experiment also showed that a pictorial presentation of data and a verbal presentation of hypotheses affect performance negatively. The results demonstrate the role of problem representation in problem solving, and, in particular, the role of homogeneity in representing data and hypotheses in hypothetico-deductive reasoning.     

Improving academic attitudes among ethnic minority youth at risk for early school leaving: the interactive effects of cross‐group friendships and ethnic identity

A growing body of research suggests that positive interethnic experiences enhance academic attitudes among ethnic minority youth. A number of studies also show that minority youth with an achieved ethnic identity have better academic attitudes and performance. Integrating these literatures, we aim to verify the combined effects of cross‐group friendships and ethnic identity on academic attitudes among a sample of youth at risk for early school leaving. The results showed that cross‐group friendships had a positive impact on academic attitudes for minority youth, but not for majority youth. However, individual levels of ethnic identity moderated these effects, which held true for minority youth with higher levels of ethnic identity. The theoretical and practical implications of these findings are discussed.     

Telling tales in school: extended contact interventions in the classroom

Extended contact has demonstrated its effectiveness in promoting more positive intergroup attitudes among children in previous experimental research. The current project evaluates the use of extended contact interventions involving story‐telling in two novel school settings: the United States (N = 213) and Italy (N = 222) among children aged 5–12 years. Findings indicate support for the effectiveness of the interventions in these two locations among younger minority and majority children but call into question the durability of positive outcomes. Applications and implications are discussed.     

The influence of affective factors on time perception

Several studies have suggested that both affective valence and arousal affect the perception of time. However, in previous experiments, the two affective dimensions have not been systematically controlled. In this study, standardized photographic slides rated for emotional valence and arousal were projected to two groups of subjects for 2, 4, and 6 sec. One group of subjects estimated the projection duration on an analog scale, whereas the second group of subjects reproduced the intervals by pushing a button. Heart rate and skin conductance responses were also recorded during stimulus presentation as indices of attention and arousal. Time estimation results showed neither a main effect of valence nor a main effect of arousal. A highly significant valence × arousal interaction affected duration judgments. For low-arousal stimuli, the duration of negative slides was judged relatively shorter than the duration of positive slides. For high-arousal stimuli, the duration of negative slides was judged longer than the duration of positive slides. The same interaction pattern was observed across judgment modalities. These results are interpreted in terms of a model of action tendency, in which the level of arousal controls two different motivational mechanisms, one emotional and the other attentional.     

Lightness, equivalent backgrounds, and anchoring

Observers compared two center/surround configurations haploscopically. One configuration consisted of a standard surface surrounded by two, three, or four surfaces, each with a different luminance. The other configuration consisted of a comparison surface surrounded by a single annulus that varied in luminance. Center surfaces always had the same luminance but only appeared to have the same lightness with certain annuli (equivalent backgrounds). For most displays, the luminance needed to obtain an equivalent background was close to the highest luminance in the standard surround configuration. Models based on the space-average luminance or the space-average contrast of the standard surround configuration yielded poorer fits. Implications for computational models of lightness and for candidate solutions to the anchoring problem are discussed.     

Different WAIS-R short forms and their relation to ethnicity

Potential racial bias on commonly used WAIS-R short forms was examined in a group of 201 African-Americans matched with Caucasians in terms of age, education, gender, and occupational status. Within racial groups, all short form IQs correlated highly with the WAIS-R IQs (all rs 0.87). Although relatively large racial differences emerged on the Block Design, Vocabulary, and Arithmetic subtests, only mild racial discrepancies emerged for three out of the seven short forms investigated. While the magnitude of the results for the short forms was mild, based on these findings it was suggested that certain short forms not be used with African-Americans in order to minimize the potential influence of racial basis.     

Definition and classification of cancer: Monothetic or polythetic?

Since the microbiological revolution, most infectious diseases have been defined and classified according to an etiologic criterion, i.e. the identification of single, external “necessary” causes (for example, Mycobacterium for tuberculosis). This is not the case with cancer. Not only external “necessary” causes of cancer have not been identified, but also the morphological classification cannot be based on univocal criteria. Although “neoplasia” and “anaplasia” appear to be universal attributes of cancer, these events are only quantitative. Neoplastic growth can be fast or slow (development may take weeks or years), and tissue pathologies are difficult to detect from normal tissue in some cancers but are obvious in others. Common special properties of anaplasia appear to be concealed in the wide range of morphologies. In the absence of a coherent morphological definition, and of external necessary causes (such as bacteria for infectious diseases), a mechanistic definition could be adopted. However, unless molecular biology discovers specific mechanistic steps in carcinogenesis, which indicate the existence of “necessary” events in carcinogenesis, we cannot adopt a univocal (monothetic) definition of cancer. The alternative is to use a polythetic definition, according to Wittgenstein's model of a “long rope twisted together out of many shorter fibres.”     

On the status of proofs by contradiction in the seventeenth century

In this paper I show that proofs by contradiction were a serious problem in seventeenth century mathematics and philosophy. Their status was put into question and positive mathematical developments emerged from such reflections. I analyse how mathematics, logic, and epistemology are intertwined in the issue at hand. The mathematical part describes Cavalieri's and Guldin's mathematical programmes of providing a development of parts of geometry free of proofs by contradiction. The logical part shows how the traditional Aristotelean doctrine that perfect demonstrations are causal demonstrations influenced the reflection on proofs by contradiction. The main protagonist of this part is Wallis. Finally, I analyse some epistemological developments arising from the Cartesian tradition. In particular, I look at Arnauld's programme of providing an epistemologically motivated reformulation of Geometry free of proofs by contradiction. The conclusion explains in which sense these epistemological reflections can be compared with those informing contemporary intuitionism.     

I know a dog when I see one: dogs (Canis familiaris) recognize dogs from videos

Animal Cognition - Several aspects of dogs’ visual and social cognition have been explored using bi-dimensional representations of other dogs. It remains unclear, however, if dogs do...