On bias in magnitude scaling and some conjectures of Stevens

Bias in magnitude scaling can be viewed as involving deviations of judgments from proportionality. A model of bias is shown to provide a theoretical basis for Stevens's conjecture about geometrically averaging magnitude estimation and magnitude production exponents in order to obtain an estimate of the psychophysical exponent. An overlooked result is that one can also obtain an estimate of the magnitude of the bias. Examples from several well-known studies are presented. The bias is also shown to vary in response to experimental manipulation of the stimulus range. Aspects of predicting exponents across experiments are clarified, and a new prediction is examined. The model of bias fills some theoretical gaps in magnitude scaling and clarifies underlying assumptions and predictions.     

Aggregation, acquiescence, and the assessment of trait affectivity

General affect ratings are subject to problems that lessen their validity. Some critics therefore have argued that aggregated on-line ratings provide better measures of trait affectivity. However, aggregated mood ratings suffer from two significant problems. First, correlations among same-valenced affects are substantially higher, indicating poorer discriminant validity. Second, cross-valence correlations are much weaker, reflecting a virtual absence of bipolarity. We show how both of these effects are due to an inflated acquiescence component in aggregated data. We also demonstrate that (a) these effects are a direct result of the aggregation process itself and (b) controlling for acquiescence counteracts these effects. These results indicate that the validity of aggregated mood ratings is lessened by an augmented acquiescence component.     

On testing hypotheses regarding a class of covariance structures

Let x be ap-component random variable having a multivariate normal distribution with covariance matrix . In this paper, we consider the problem of testing hypotheses of the formH ₀: =b ₁₁ + +b _{m m} , whereb _i 's are unknown scalars, and _i 's are a set of known and simultaneously diagonalizable matrices. This problem has both psychometric and statistical interest, and its basic theory is developed here. Besides, the problem of obtaining likelihood-ratio statistic for testingH ₀ is studied, and the statistic obtained in a special case.     

On matters of mind and body: regarding Descartes

In this paper the author considers Descartes’ place in current thinking about the mind‐body dilemma. The premise here is that in the history of ideas, the questions posed can be as significant as the answers acquired. Descartes’ paramount question was ‘How do we determine certainty?’ and his pursuit of an answer led to cogito ergo sum. His discovery simultaneously raised the question whether mind is separate from or unified with the body. Some who currently hold that brain and subjectivity are unified contend that the philosopher ‘split’ mind from body and refer to ‘Descartes’ error’. This paper puts forward that Descartes’ detractors fail to recognise Descartes’ contribution to Western thought, which was to introduce the Enlightenment and to give a place to human subjectivity. Added to this, evidence from Descartes’ correspondence with Princess Elisabeth of Bohemia supports the conclusion that Descartes did in fact believe in the unity of mind and body although he could not reconcile this rationally with the certainty from personal experience that they were separate substances. In this Descartes was engaged in just the same dilemma as that of current thinkers and researchers, a conflict which still is yet to be resolved.