Coherent modulation of stimulus colour can affect visually induced self-motion perception

The effects of dynamic colour modulation on vection were investigated to examine whether perceived variation of illumination affects self-motion perception. Participants observed expanding optic flow which simulated their forward self-motion. Onset latency, accumulated duration, and estimated magnitude of the self-motion were measured as indices of vection strength. Colour of the dots in the visual stimulus was modulated between white and red (experiment 1), white and grey (experiment 2), and grey and red (experiment 3). The results indicated that coherent colour oscillation in the visual stimulus significantly suppressed the strength of vection, whereas incoherent or static colour modulation did not affect vection. There was no effect of the types of the colour modulation; both achromatic and chromatic modulations turned out to be effective in inhibiting self-motion perception. Moreover, in a situation where the simulated direction of a spotlight was manipulated dynamically, vection strength was also suppressed (experiment 4). These results suggest that observer's perception of illumination is critical for self-motion perception, and rapid variation of perceived illumination would impair the reliabilities of visual information in determining self-motion.     

Relationship between types of humour and stress response and well‐being among children in Japan

This study examined the relationship between three types of children's humour (aggressive, self‐defeating, and playful) and the children's stress response and well‐being in the Japanese context, where a collectivistic culture is prevalent. To do so, 500 study participants (250 elementary and 250 junior high school students) were recruited. The participants reported the types of humour, stress responses, and level of well‐being that they experienced. After correlation analysis, aggressive humour and playful humour showed a positive correlation with stress responses; in addition, aggressive humour showed a negative correlation with well‐being. Self‐defeating humour showed a negative correlation with stress responses and a positive correlation with well‐being. We also conducted a cluster analysis using the scores for the three types of humour, analysing four groups: “aggressive humourists” (respondents who demonstrated above‐average aggressive humour and scored average for all other humours), “nonhumourists” (below‐average humour in all areas), “self‐deprecating humourists” (above‐average self‐defeating humour, below‐average aggressive humour, and average playful humour), and “multiple humourists” (above‐average humour in all areas). Upon comparing the results of stress responses and well‐being scores among the four groups, we found that self‐deprecating humourists reported the highest level of well‐being. These results show that in collectivistic cultures, self‐defeating humour may be adaptive.     

Effects of discrete-trial and free-operant procedures on the acquisition and maintenance of successive discrimination in rats.

Rats were trained on a successive discrete-trial discrimination between two tonal stimuli to examine the effects of availability of a lever during intertrial intervals. In the discrete-trial condition, in which a lever was removed from the chamber during intertrial intervals, 10-s trials were initiated by the presentation of both discriminative stimulus and lever. In the free-operant condition, in which a lever was present during both trials and intertrial intervals, 10-s trials were initiated only by the presentation of a discriminative stimulus. Experiment 1 employed 50-s intertrial intervals and demonstrated that discriminative performances were acquired faster and maintained better in the free-operant conditions than in the discrete-trial conditions. Experiment 2 employed 5-s intertrial intervals and showed that poor discriminative performances in the discrete-trial conditions were improved. These results indicate that the presentation of a lever to start a trial can overshadow or mask the control by a discriminative stimulus and thereby obstruct the acquisition and maintenance of discriminative performances. Furthermore, the overshadowing or masking effects are strengthened as a function of the duration of intertrial intervals.     

Effects of variations in force and stimulus uncertainty on fractionated reaction time.

Previous research has shown that reaction time (RT) and premotor time varied as a function of force even in simple-RT paradigm. The present purpose was to examine whether stimulus uncertainty induced by catch trials would cause programming delay until after the signal to respond. Subjects were required to react and produce a designated peak force as soon as possible after a visual stimulus, with and without catch trials. Five different levels of force were 10, 30, 50, 70, and 90% of the maximum grip strength of subjects. Analysis showed that simple RT and premotor time changed as a function of force, regardless of whether catch trials were removed. These findings suggest that stimulus uncertainty is not a necessary condition for programming delay.     

Central synaptic mechanisms underlie short-term olfactory habituation in Drosophila larvae

Naive Drosophila larvae show vigorous chemotaxis toward many odorants including ethyl acetate (EA). Chemotaxis toward EA is substantially reduced after a 5-min pre-exposure to the odorant and recovers with a half-time of ～20 min. An analogous behavioral decrement can be induced without odorant-receptor activation through channelrhodopsin-based, direct photoexcitation of odorant sensory neurons (OSNs). The neural mechanism of short-term habituation (STH) requires the (1) rutabaga adenylate cyclase; (2) transmitter release from predominantly GABAergic local interneurons (LNs); (3) GABA-A receptor function in projection neurons (PNs) that receive excitatory inputs from OSNs; and (4) NMDA-receptor function in PNs. These features of STH cannot be explained by simple sensory adaptation and, instead, point to plasticity of olfactory synapses in the antennal lobe as the underlying mechanism. Our observations suggest a model in which NMDAR-dependent depression of the OSN-PN synapse and/or NMDAR-dependent facilitation of inhibitory transmission from LNs to PNs contributes substantially to short-term habituation.     

Sex differences in the Schizotypal Personality Questionnaire Brief among Japanese employees and undergraduates: A cross-sectional study

Schizotypal personality may be seen as an indicator predisposition to schizophrenia and psychosis proneness. Schizotypal personality traits behave differently depending on a person’s age and sex, but few studies have examined the causal relationship between age-related sex differences and schizotypal personality traits. The aim of the present study was to examine the relationship between the schizotypal personality and sex in different age groups. In our study, we used the Schizotypal Personality Questionnaire Brief (SPQ-B). Participants were 371 college students (107 men) with an age range from 18 to 25 years, and 322 working people (156 men) with an age range of 22–67 years. The results showed that the young adult males in the college student group had tendencies to score higher than females in the same group on the SPQ-B total score and its two subscale scores (the cognitive-perceptual and the interpersonal scores). In the adult sample taken in the working people group, the total score and subscale scores of the SPQ-B did not significantly discriminate male subjects from female subjects. These findings indicate that sex differences of schizotypal personality traits may reflect differential age-related variation.     

Comparison of ruminative responses with negative rumination as a vulnerability factor for depression

Several studies have shown that the ruminative responses, which are defined as a coping pattern that focuses on the symptoms of depression and on the possible causes and consequences of these symptoms, are associated with depression. Recently, negative rumination, which is defined as the tendency to continue to think about something bad, harmful, or unhopeful for a long time, has been proposed as a vulnerability factor for depression. The purpose of this study was to compare depression scores associated with negative rumination and ruminative responses. We expected to find depression associated with negative rumination. The sample consisted of 188 Japanese undergraduate students (83 men: M age= 19.0 yr., SD= 1.1; 105 women: M age = 19.1 yr., SD = 1.7) taking a human sciences course at a Japanese university. Subjects participated in an 8-mo. longitudinal study. Logistic analysis indicated that negative rumination was a significant predictor of depression. However, ruminative responses as a whole were not a significant predictor of depression after controlling for negative rumination. These findings suggest that it is important to distinguish whether rumination is focused on negative or nonnegative subject matter.     

Effects of variations in force on fractionated reaction time in simple and choice conditions

The present study examined the effects of force output on fractionated reaction time under simple and choice conditions. 20 subjects were required to react and produce a designated force as soon as possible after a visual stimulus. Five different levels of force were 10, 30, 50, 70, and 90% of the maximum grip strength of the subjects. Analysis showed that reaction time (RT) changed as a function of force in both conditions, with the longest RT occurring at the 70% condition. The same pattern was also evident for premotor time. These findings suggest that the changes in RT with increases in force are mediated predominantly by central rather than peripheral processes.