An interactive fuzzy satisficing method for multiobjective stochastic linear programming problems using chance constrained conditions

Two major approaches to deal with randomness or ambiguity involved in mathematical programming problems have been developed. They are stochastic programming approaches and fuzzy programming approaches. In this paper, we focus on multiobjective linear programming problems with random variable coefficients in objective functions and/or constraints. Using chance constrained programming techniques, the stochastic programming problems are transformed into deterministic ones. As a fusion of stochastic approaches and fuzzy ones, after determining the fuzzy goals of the decision maker, interactive fuzzy satisficing methods to derive a satisficing solution for the decision maker by updating the reference membership levels is presented. Copyright © 2003 John Wiley & Sons, Ltd.     

Spatiotemporal balance in competing apparent motion is not predicted from the strength of the single-motion percept

Apparent motion is useful for investigating how spatiotemporal cues are integrated to determine the identity of a moving object. To examine its spatiotemporal properties, a competing-motion paradigm has advantages in strict psychophysical evaluation, despite difficulty in object-identity determination, over a non-competing subjective-grading paradigm. The latter has been often used, whereas the former has not been fully investigated. Here, we compared these two paradigms. In the competing-motion experiment, a sample spot was followed by a far and a near test spot with onset asynchrony. We found that the onset asynchrony between the near and far test spots was directly related to the distance ratio between them. This spatial size-invariant relation was not predicted from the strength of the single-apparent-motion percept, estimated from the non-competing subjective-grading experiment in which a sample spot was followed by only one test spot. Moreover, the spatiotemporal balance in competing apparent motion was found not to be valid under negative interstimulus-interval conditions, although a single apparent motion is perceived in those conditions. These clear discrepancies suggest that competing and single apparent motions are processed in a different way according to the difficulty in object identification.     

Facilitation of Sodium Aversion Learning in Sodium-Deprived Rats

Two experiments with rats explored the effects of sodium deprivation induced by furosemide injections upon acquisition of taste aversion to sodium chloride (NaCl). In Experiment 1, rats under either sodium deprivation or a balanced nutrition condition were given access to a limited amount of NaCl solution prior to poisoning. When all rats were tested under sodium repletion, the previously sodium-deprived rats consumed less NaCl than did the nondeprived rats. This finding was replicated in Experiment 2A in which ingestion of a compound solution of NaCl and hydrochloric acid (HCl) was followed by poisoning. Consumption of HCl, however, showed the opposite pattern: the sodium-deprived rats drank more HCl than did the nondeprived rats, a result that was replicated in Experiment 2B. These results suggest that sodium deprivation strengthens the salience of NaCl, thereby facilitating acquisition of aversion to this taste and strongly overshadowing that to a simultaneously presented taste.     

Self-awakening, sleep inertia, and P3 amplitude in elderly people

It is well known that sleepiness is sometimes experienced in the afternoon. A short afternoon nap is thought to be effective in reducing sleepiness. However, sleep inertia occurs even after a short nap, and this could be a major risk factor for injuries from falling by the elderly. In the present study, the effect of self-awakening on sleep inertia after a 20-min. nap was examined. Nine participants (M=74.1 yr., SD=5.0 yr.) took part in the three experimental conditions: the self-awakened nap, the forced-awakened nap, and the control (no-nap) conditon. Analysis showed sleepiness and performance after the nap significantly improved compared with the control condition. P3 amplitude tended to be larger after self-awakening than after forced-awakening. The present study indicates a 20-min. nap reduces afternoon sleepiness, and the application of self-awakening may contribute to higher arousal after a nap taken by this elderly group.     

Are Japanese groups more competitive than Japanese individuals? A cross‐cultural validation of the interindividual–intergroup discontinuity effect

The interindividual–intergroup discontinuity effect is the tendency for relationships between groups to be more competitive than the relationships between individuals. It has been observed robustly in studies conducted in the United States, which is a society characterized as “individualistic.” In this study, it was explored whether the effect was replicable in a “collectivistic” society such as Japan. From the traditional view in cross‐cultural psychology, which emphasizes the collectivistic nature of East Asian peoples, it was expected that the discontinuity effect would be greater in Japan than in the United States. On the other hand, based on recent empirical findings suggesting that North Americans are no less group‐oriented than East Asians, it was expected that the discontinuity effect would be no greater in Japan than in the United States. One hundred and sixty Japanese university students played a 10‐trial repeated prisoner's dilemma game: 26 sessions of interindividual and 18 sessions of intergroup. Following exactly the procedure of prior experiments in the US, individuals and groups were allowed face‐to‐face communication with their opponents before making their decisions, and participants in the intergroup condition were further allowed to converse freely with their in‐group members. Results replicated previous findings in the United States; groups made more competitive choices than did individuals. In addition, neither the magnitude of the discontinuity effect, nor the frequency of competitive choices made by the groups, were larger in Japan than they were in the majority of prior studies conducted in the United States. These findings suggest cross‐cultural robustness of the interindividual–intergroup discontinuity effect. Also, interestingly, they contradict the simple distinction between individualism and collectivism. Implications for studies of culture and group processes are discussed.     

Does Mealtime Communication Improve Happiness? Considering the Trait of Shyness1

Shared mealtimes have been found to be important daily rituals with positive effects on behavior and mental health, such as increasing subjective well-being. However, most previous studies have not considered possible barriers to these positive effects, specifically shyness. We investigated the relationships among shared mealtime quality, shyness, and subjective well-being, and the moderating role of shyness in the relationship between the other two variables by surveying a sample of college students (n = 305). Correlational analyses revealed that shared mealtime quality was negatively associated with shyness and positively associated with subjective well-being. Hierarchical regression analyses revealed that shared mealtime quality was significantly associated with subjective well-being, as was the interaction between the friend factor of shared mealtime quality and shyness. Therefore, shared mealtime quality might help improve happiness, but shyness should be considered a possible barrier to this beneficial effect when meals are shared with friends.     

Sensory Processing Sensitivity Moderates the Relationships Between Life Skills and Depressive Tendencies in University Students1

University students often experience depressive symptoms, and strengthening of life skills may be beneficial for improving their mental health. Several studies have suggested that life skills effective in reducing depressive tendencies vary by individuals depending on differences in sensory processing sensitivity (SPS). SPS is a genetically determined trait characterized by sensitivity and reactivity to environmental stimuli. This study investigated the relationship between life skills and depressive tendencies based on individual differences in SPS. A total of 868 Japanese university students (mean age = 19.8 years, SD = 1.3 years) completed a questionnaire measuring levels of SPS—decision-making, interpersonal relationships, effective communication, and emotional coping skills—and depressive tendencies. Hierarchical multiple regression and simple slopes analyses indicated that interpersonal relationship skills were negatively correlated with depression regardless of SPS levels. Furthermore, decision-making skills were negatively correlated with depressive tendencies only in low-SPS students. Emotional coping skills were negatively correlated with depressive tendencies in high-SPS students. These results may help universities incorporate SPS levels when creating life-skills-based interventions for students.     

Attending inside or outside: A Japanese–US comparison of spontaneous memory of group information

A recent review of empirical evidence disconfirmed the widely‐held view that North Americans are less collectivistic than East Asians. However, previous research has proposed that the motivations underlying group behaviours differ across cultures: North Americans are more strongly motivated to acquire and maintain higher in‐group status relative to outgroups, whereas East Asians tend to emphasize maintenance of reciprocal relationships within in‐groups. We tested this hypothesis by examining the pattern of attentional allocation in group situations using a memory task. As predicted, compared to Japanese, memory performance among Americans was biased towards intergroup status difference over intragroup relationship information.