A new definition of well-behaved discrimination functions

A discrimination function shows the probability or degree with which stimuli are discriminated from each other when presented in pairs. In a previous publication [Kujala, J.V., & Dzhafarov, E.N. (2008). On minima of discrimination functions. Journal of Mathematical Psychology, 52, 116–127] we introduced a condition under which the conformity of a discrimination function with the law of Regular Minimality (which says, essentially, that “being least discriminable from” is a symmetric relation) implies the constancy of the function’s minima (i.e., the same level of discriminability of every stimulus from the stimulus least discriminable from it). This condition, referred to as “well-behavedness,” turns out to be unnecessarily restrictive. In this note we give a significantly more general definition of well-behavedness, applicable to all Hausdorff arc-connected stimulus spaces. The definition employs the notion of the smallest transitively and topologically closed extension of a relation. We provide a transfinite-recursive construction for this notion and illustrate it by examples.     

Regular Minimality and Thurstonian-type modeling

A Thurstonian-type model for pairwise comparisons is any model in which the response (e.g., “they are the same” or “they are different”) to two stimuli being compared depends, deterministically or probabilistically, on the realizations of two randomly varying representations (perceptual images) of these stimuli. The two perceptual images in such a model may be stochastically interdependent but each has to be selectively dependent on its stimulus. It has been previously shown that all possible discrimination probability functions for same–different comparisons can be generated by Thurstonian-type models of the simplest variety, with independent percepts and deterministic decision rules. It has also been shown, however, that a broad class of Thurstonian-type models, called “well-behaved” (and including, e.g., models with multivariate normal perceptual representations whose parameters are smooth functions of stimuli) cannot simultaneously account for two empirically plausible properties of same–different comparisons, Regular Minimality (which essentially says that “being least discriminable from” is a symmetric relation) and nonconstancy of the minima of discrimination probabilities (the fact that different pairs of least discriminable stimuli are discriminated with different probabilities). These results have been obtained for stimulus spaces represented by regions of Euclidean spaces. In this paper, the impossibility for well-behaved Thurstonian-type models to simultaneously account for Regular Minimality and nonconstancy of minima is established for a much broader notion of well-behavedness applied to a much broader class of stimulus spaces (any Hausdorff arc-connected ones). The universality of Thurstonian-type models with independent perceptual images and deterministic decision rules is shown (by a simpler proof than before) to hold for arbitrary stimulus spaces.     

Early life origins of psychological development and mental health

According to the Developmental Origins of Health and Disease (DOHaD)‐hypothesis, conditions early in life may have life‐long consequences. In a series of epidemiological birth cohort and clinical studies and natural experiments, we have had the chance to test the extent to which this hypothesis is useful in understanding individual differences in psychological development and mental health. Our findings have provided evidence that individual differences in cognitive, social and emotional development and in mental health may lie in early life circumstances, and add significantly to the literature by pointing out which periods of early growth are the most critical. These findings are also important in translating pre‐clinical evidence to humans. What remains less clear, however, is what the mechanisms of programming are. Thus, further research is needed to elucidate these mechanisms before information on the early life origins of health and disease can be used in designing prevention and intervention programs.     

Personality profiles and health: Longitudinal evidence among Finnish adults

Kinnunen, M.‐L., Metsäpelto, R. L., Feldt, T., Kokko, K., Tolvanen, A., Kinnunen, U., Leppänen, E. & Pulkkinen, L. (2012). Personality profiles and health: Longitudinal evidence among Finnish adults. Scandinavian Journal of Psychology 53, 512–522. This study investigates the associations of longitudinal Big Five personality profiles with long‐term health in 304 adults (53% males). Personality traits (Neuroticism, Extraversion, Openness, Conscientiousness, Agreeableness) were assessed at ages 33, 42, and 50. Subjective (self‐rated health, symptoms, psychological distress) and objective (body mass index, waist‐to‐hip ratio, blood pressure, cholesterol, triglycerides) indicators of health were measured at ages 42 and 50. Five longitudinally stable personality profiles were extracted over 17 years by latent profile analysis. The levels of traits were the same in each profile at each age. Resilient individuals (N = 65; Neuroticism low, other traits high) had the best subjective health and Overcontrolled individuals (N = 40; Neuroticism high, other traits low) the poorest health over eight years. Reserved individuals (N = 25; high Conscientiousness, other traits low), Undercontrolled (N = 41; high Openness and Extraversion, low Conscientiousness), and Ordinary (N = 133; all traits scored medium) individuals were in the middle of these extremes in subjective health. No differences between the profiles were found in the objective indicators of health. Thus, overcontrol and resilience were most discriminative in terms of good health. Moreover, personality profiles revealed associations with health to be more nuanced than simply being composed of single traits. High Extraversion needed to be combined with high Conscientiousness (Resilients) in order to be associated with the best health; high Extraversion with low Conscientiousness (Undercontrolled) was associated with average health; and low Extraversion with high Neuroticism (Overcontrolled) was associated with the poorest health.     

Development of sense of coherence during two group interventions

Kähönen, K., Näätänen, P., Tolvanen, A. & Salmela‐Aro, K. (2012). Development of sense of coherence during two group interventions. Scandinavian Journal of Psychology 53, 523–527. Burnout is a serious occupational hazard. This study investigated the possibility to develop an effective salutogenic group intervention among employees suffering from severe burnout symptoms. Participants consisted of employees aged 31 to 59 years working in different public service occupations, such as police officers, tax officers, (and other public service officers), and assigned to three different groups: analytic (N = 25), psychodramatic (N = 24) and controls (N = 28). The intervention comprised 16 separate days over a nine‐month period. Changes in sense of coherence (SOC) were measured four times with the 13‐item Orientation to Life Questionnaire during the intervention and at six‐month follow‐up, and analyzed by general linear model (GLM) and using Cohen’s d to estimate effect sizes. Change in SOC between the three groups was statistically significant (F(4,148) = 2.65, p = 0.036). The psychodrama group showed a higher increase in SOC than the analytic group during the intervention, while the improvement in the analytic group was significant during the six‐month follow‐up. Total effect size from baseline to follow‐up was in the analytic group 0.71, in the psychodrama group 0.47, and in the control group from baseline to end of intervention 0.09. The results show that it is possible to improve SOC by group intervention in the occupational healthcare context. The dialogue‐based analytic method and action‐based psychodramatic method differ in their specific effects.     

Reciprocity of trust in the supervisor–subordinate relationship: The mediating role of autonomy and the sense of power

This article develops and tests a model of reciprocal trust between supervisor and subordinate. Drawing from literature on trust and control and on the approach/inhibition theory of power, the authors present a model in which supervisor trust is suggested to enhance subordinate reciprocal trust through increased work-related autonomy and a heightened sense of power. The mediator analysis using the two-level full structural model confirmed that the relationship between supervisor trust and subordinate trust was partially mediated by the suggested chain of variables. The article responds to a call for empirical studies on reciprocal trust and offers a complementary mechanism for trust building beside characteristics and relationship-based approaches.     

'Magic-size' GeSi and Si nanocrystals created by ion bombardment of hexagonal SiC; a molecular dynamics study

We recently showed that GeSi and Si nanocrystals created after Ge- and Si-ion implantation into hexagonal SiC and subsequent annealing contain a high percentage of hexagonality. Here we demonstrate that the nanocrystals are of 'magic sizes' and are microtwinned. Both these features are explained by molecular dynamics calculations.     

Low Self-Esteem as a Risk Factor for Loneliness in Adolescence: Perceived - but not Actual - Social Acceptance as an Underlying Mechanism

Low self-esteem has been shown to relate to concurrent and later feelings of loneliness in adolescence. However, it remains unclear why low self-esteem puts adolescents at risk for experiencing loneliness. Further, longitudinal research on the direction of effects between loneliness and self-esteem is virtually non-existent. The present study aims to fill these gaps in the literature. First, the direction of effects between loneliness and self-esteem was investigated in two independent longitudinal studies: a five-wave study sampling Dutch adolescents (M age?=?15.22 years at T1; 47 % female; N?=?428) and a three-wave study sampling Belgian adolescents (M age?=?14.95 years at T1; 63 % female; N?=?882). Second, the underlying role of social acceptance was investigated in the latter sample by applying a multi-method approach that included actual (i.e., peer-reported) and perceived (i.e., self-reported) social acceptance. Results indicated that self-esteem and loneliness influenced one another in a reciprocal manner. Furthermore, the dominant path from self-esteem to loneliness was partially mediated by perceived—but not actual—social acceptance. The importance of distinguishing actual from perceived social acceptance is discussed, and suggestions for future research are outlined.     

Obtaining the best value for money in adaptive sequential estimation

In [Kujala, J. V., Richardson, U., &; Lyytinen, H. (2010). A Bayesian-optimal principle for learner-friendly adaptation in learning games. Journal of Mathematical Psychology, 54(2), 247–255], we considered an extension of the conventional Bayesian adaptive estimation framework to situations where each observable variable is associated with a certain random cost of observation. We proposed an algorithm that chooses each placement by maximizing the expected gain in utility divided by the expected cost. In this paper, we formally justify this placement rule as an asymptotically optimal solution to the problem of maximizing the expected utility of an experiment that terminates when the total cost overruns a given budget. For example, the cost could be defined as the random time taken by each trial in an experiment, and one might wish to maximize the expected total information gain over as many trials as can be completed in 15 min. A simple, analytically tractable example is considered.