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.     

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.     

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.     

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.     

A comparison of subset selection and analysis of covariance for the adjustment of confounders

Two common methods for adjusting group comparisons for differences in the distribution of confounders, namely analysis of covariance (ANCOVA) and subset selection, are compared using real examples from neuropsychology, theory, and simulations. ANCOVA has potential pitfalls, but the blanket rejection of the method in some areas of empirical psychology is not justified. Assumptions of the methods are reviewed, with issues of selection bias, nonlinearity, and interaction emphasized. Advantages of ANCOVA include better power, improved ability to detect and estimate interactions, and the availability of extensions to deal with measurement error in the covariates. Forms of ANCOVA are advocated that relax the standard assumption of linearity between the outcome and covariates. Specifically, a version of ANCOVA that models the relationship between the covariate and the outcome through cubic spline with fixed knots outperforms other methods in simulations.     

Principal components analysis of the Psychological Screening Inventory in a sample of substance abusers.

A principal components analysis of responses to the Psychological Screening Inventory from a sample of substance abusers was conducted. Subjects were 153 inpatients admitted to a midwestern program for chemical dependency treatment. Means for age and education were 28.0 yr. (SD = 8.1) and 11.4 (SD = 1.8), respectively. Analysis indicated that a two-factor solution best described these data. Factor 1 reflected over-all maladjustment, while Factor 2 was a measure of extroversion. Clinical utility of the inventory was discussed.     

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...     

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.     

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.