Effects of intergroup and interpersonal context, and individuals' appraisal of their in-group on the intragroup comparison process

The present study examined whether individuals' endorsement of intergroup context moderates the social comparison process not only in the intergroup upward comparison condition, but also in the downward comparison condition, by experimentally manipulating the direction of intergroup comparison and interpersonal comparison for participants who appraise their in-group as high or low. As predicted, participants who appraise their in-group as high showed reflection processes in the intergroup upward comparison condition, but comparison processes in the intergroup downward comparison condition because of their endorsement of their in-group position. In contrast, participants who appraised their in-group as low showed comparison processes in the intergroup upward comparison condition, but reflection processes in the intergroup downward comparison condition. These results imply that the interplay between intergroup context and individuals' internal factors affect intragroup comparison processes.     

Leptin inhibits and ghrelin augments hypothalamic noradrenaline release after stress

Metabolic conditions affect hypothalamo-pituitary-adrenal responses to stressful stimuli. Here we examined effects of food deprivation, leptin and ghrelin upon noradrenaline release in the hypothalamic paraventricular nucleus (PVN) and plasma adrenocorticotropic hormone (ACTH) concentrations after stressful stimuli. Food deprivation augmented both noradrenaline release in the PVN and the increase in plasma ACTH concentration following electrical footshocks (FSs). An intracerebroventricular injection of leptin attenuated the increases in hypothalamic noradrenaline release and plasma ACTH concentrations after FSs, while ghrelin augmented these responses. These data suggest that leptin inhibits and ghrelin facilitates neuroendocrine stress responses via noradrenaline release and indicate that a decrease in leptin and an increase in ghrelin release after food deprivation might contribute to augmentation of stress-induced ACTH release in a fasting state.     

Decision-making deficit of a patient with axonal damage after traumatic brain injury

Patients with traumatic brain injury (TBI) were reported to have difficulty making advantageous decisions, but the underlying deficits of the network of brain areas involved in this process were not directly examined. We report a patient with TBI who demonstrated problematic behavior in situations of risk and complexity after cerebral injury from a traffic accident. The Iowa gambling task (IGT) was used to reveal his deficits in the decision-making process. To examine underlying deficits of the network of brain areas, we examined T1-weighted structural MRI, diffusion tensor imaging (DTI) and Tc-ECD SPECT in this patient. The patient showed abnormality in IGT. DTI-MRI results showed a significant decrease in fractional anisotropy (FA) in the fasciculus between the brain stem and cortical regions via the thalamus. He showed significant decrease in gray matter volumes in the bilateral insular cortex, hypothalamus, and posterior cingulate cortex, possibly reflecting Wallerian degeneration secondary to the fasciculus abnormalities. SPECT showed significant blood flow decrease in the broad cortical areas including the ventromedial prefrontal cortex (VM). Our study showed that the patient had dysfunctional decision-making process. Microstructural abnormality in the fasciculus, likely from the traffic accident, caused reduced afferent feedback to the brain, resulting in less efficient decision-making. Our findings support the somatic-marker hypothesis (SMH), where somatic feedback to the brain influences the decision-making process.     

Social Networks as a Factor in Volunteering Among Elderly Japanese with Lower Socioeconomic Status

We investigated the effect of social networks on volunteering, which is known to be beneficial for people and society, among elderly Japanese of lower socioeconomic status. Western studies have demonstrated that social networks boost volunteering among wealthy people because of the norm that they should help the less fortunate. However, wealthy East Asians do not share this norm. Therefore, socioeconomic variables and volunteering tend not to be significantly related in Japan. We hypothesized that social networks would be more important to volunteering among the Japanese elderly, especially among people of a lower socioeconomic status. A total of 768 respondents (319 men, 432 women, 17 sex unspecified; M_age = 73.99 years, SD = 7.40 years) completed the survey. The results indicated that social networks were positively related to volunteering only among people with lower financial status. This result suggests that social networks can increase opportunities and help less advantaged elderly people to reap the benefits of volunteering.     

STAZ: Interactive software for undergraduate statistics

STAZ is an interactive computer program that demonstrates statistical concepts, many of which cannot be readily demonstrated using conventional methods. Use of dynamic graphics encourages active engagement with challenging statistical concepts. The program consists of 13 graphical demonstrations, most of which allow for interactive participation by students. A detailed Help file with guided explanations accompanies each demonstration. STAZ is a multiple document interface program that makes full use of Windows features, such as tiling, links, and multitasking. Designed to be used as a supplement for any undergraduate statistics course, STAZ may be used by either instructors in classroom settings or students working independently.     

Parallel scanning of physical and category information

In Sternberg's memory scan paradigm, subjects were required to scan for category membership or physical identity. In Experiment I, the scan rate when checking for either type of relationship at the same time was less than the sum of the scan rates when checking for either relationship separately. In Experiment II, presenting memory sets consisting of items from a single category affected the category scan function but not the physical scan function. The results were interpreted as evidence for the capacity to conduct parallel scans of independent memory encodings when retrieving remembered information.     

A weak intuitionistic propositional logic with purely constructive implication

We introduce subsystems WLJ and SI of the intuitionistic propositional logic LJ, by weakening the intuitionistic implication. These systems are justifiable by purely constructive semantics. Then the intuitionistic implication with full strength is definable in the second order versions of these systems. We give a relationship between SI and a weak modal system WM. In Appendix the Kripke-type model theory for WM is given.This work was partially supported by NSF Grant DCR85-13417     

An integrative approach to leadership and social support

This study examined the effects of instrumental and socio-emotional behaviors of friends on stress reactions and task performance. A 2 (presence or absence of instrumental behavior) * 2 (presence or absence of socio-emotional behavior) * 2 (high or low legitimacy of influence) factorial design was used. Ninety-one college-age females as subjects and their close same-sex friends as confederates participated together in the experiment. Dependent variables were mean blood pressure (MBP) as a physiological stress reaction, state anxiety as a psychological stress reaction, and the level of performance in a simple arithmetic task. Instrumental behavior had a facilitating effect on task performance in the high legitimacy condition. Socio-emotional behavior showed a buffering effect on physiological stress reaction when the friend did not engage in instrumental behavior in the low legitimacy condition. These findings suggest that legitimacy of influence may be able to explain the differences between leadership and social support processes.     

Bayesian multidimensional scaling for the estimation of a Minkowski exponent

The Minkowski property of psychological space has long been of interest to researchers. A common strategy has been calculating the stress in multidimensional scaling for many Minkowski exponent values and choosing the one that results in the lowest stress. However, this strategy has an arbitrariness problem—that is, a loss function. Although a recently proposed Bayesian approach could solve this problem, the method was intended for individual subject data. It is unknown whether this method is directly applicable to averaged or single data, which are common in psychology and behavioral science. Therefore, we first conducted a simulation study to evaluate the applicability of the method to the averaged data problem and found that it failed to recover the true Minkowski exponent. Therefore, a new method is proposed that is a simple extension of the existing Euclidean Bayesian multidimensional scaling to the Minkowski metric. Another simulation study revealed that the proposed method could successfully recover the true Minkowski exponent. BUGS codes used in this study are given in the Appendix.