Event-related potentials were recorded during the presentation of a series of standard and deviant auditory stimuli (1000Hz, 870ms SOA), and mismatch negativity (MMN) was extracted to investigate pre-attentive deviant detection processes. In experiment 1, the standard was a continuous tone (170ms). The two deviant stimuli (0.1 probability each) consisted of two discrete tones (50ms) separated by a gap (70ms) or a single tone (50ms). In experiment 2, the roles of the standard and deviant stimuli were reversed. The standard consisted of two discrete tones separated by a gap and either a 170ms or a 50ms single tone was used as deviant. MMN latencies in experiment 2 were longer than those in experiment 1, inconsistent with the idea that an exact memory trace is created from stimulus repetition. Additionally, differences from the standard in the latter half of the deviant stimulus were not reflected in MMN. These results suggest the existence of multiple strategies in deviant detection as well as a shorter temporal window of integration than previously hypothesized. (Japanese Journal of Physiological Psychology and Psychophysiology, 25 (3) : 227-235, 2007.)

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The anomalous relationship between secretory immunoglobulin A (sIgA) concentration in saliva and psychosocial factors is considered to be caused by circadian variations and acute stress-induced variations in sIgA levels. To prevent such variations in sIgA levels, we investigated the relationship between sIgA concentration that was estimated upon awakening and daily events and moods. University students (N = 54) were instructed to collect their saliva samples immediately upon awakening and again after 2 weeks. On the day before saliva collection, the students completed questionnaires on their daily events and moods over the past 2 weeks. Correlations of daily events and moods and sIgA concentration changes from the first and second measurement sessions indicated that participants who reported a higher frequency of daily negative events and depressive mood exhibited lower sIgA concentrations (r =-.294 and-.283, respectively). Moreover, negative events in male participants and depressive mood in female participants were negatively correlated with sIgA concentration, whereas positive events and mood in female participants were positively correlated with sIgA concentration. We clearly demonstrated that negative and positive psychosocial factors caused a decrease and increase in sIgA concentration in saliva, respectively. (Japanese Journalof Physiological Psychology and Psychophysiology, 25 (3) : 237-244, 2007.)

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The gambling task used here requires subjects to choose cards from four decks that varied in gains and losses in order to maximize their profit. Gender and individual differences have been reported in choice behaviors as measured with the gambling task. However, how individual differences influence gender differences in the gambling task remains unclear. The aim of this study was to investigate these influences; therefore, we divided the male participants into two groups based on choice behaviors in the gambling task and measured skin conductance responses (SCRs) in two male groups and a one female group. On comparing the three groups, males who chose riskless cards showed higher punishment and anticipatory SCRs than the second male and female groups. Moreover, males other than the participants who chose riskless cards had the same reward, punishment, and anticipatory SCRs as the females. These findings suggest that inclusion of participants who chose riskless cards in the male group causes gender differences in performance and SCRs during the gambling task. (Japanese Journal of Physiological Psychology and Psychophysiology, 25 (3) : 245-254, 2007.)

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The major purpose of this study was to establish the standard rate of blinking in adults using relatively large samples of subjects. A subsidiary purpose was to investigate gender and age differences in eyeblink behaviors. The identical task, watching an edited video tape for three minutes, was administered to 671 subjects aged from 20 to 93 years. Eyeblinks of each person were videotaped during task performance and were analyzed using a special software. The results were as follows : (a) the average blink rate in adulthood was approximately 20 blinks per minute, (b) no remarkable age effects was found, but (c) the gender difference in eyeblink rate was significant, with females blinking more frequently than males. In addition, the opening and closing durations of eyeblinks, the synchronization between right and left eyelids, and the effects of wearing contact lenses and eyeglasses on eyeblink rates were examined in terms of age and gender differences. A specific influence of contact lens wearing on blink rate was obtained, namely a significant increase in blinking and prolongation of blink duration. (Japanese Journal of Physiological Psychology and Psychophysiology, 25 (3) : 255-265, 2007.)

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It has been suggested that the experimental variables known to affect P300 amplitude can be described by three general factors : subjective probability, stimulus meaning, and information transmission. Based on this triarchic model, this study investigated the factor that determines P300 amplitude in guilty knowledge tests (GKTs). Twenty university students performed a three-stimulus visual oddball task using words. Half of the participants enacted a mock crime to increase the significance of infrequent nontarget words, whereas the other half did not. P300 amplitude was larger for critical items (infrequent nontarget words) than for noncritical items (frequent nontarget words) only in the mock-crime group. The amplitude difference remained significant in a dual-task condition wherein the participants performed an auditory discrimination task simultaneously with the visual oddball task. These results suggest that P300 amplitude is larger for critical stimuli in GKTs mainly because these stimuli are more meaningful and not because the stimuli are perceived as members of a rarer stimulus category. Moreover, attentional distraction does not appear to eliminate the amplitude difference between critical and noncritical items. (Japanese Journal of Physiological Psychology and Psychophysiology, 25 (3) : 267-275, 2007.)

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This study examined whether a participant's level of attention to video clips could be assessed by event-related brain potentials to vibratory probe stimuli. Twelve university students performed a somatosensory target detection task while watching silent video clips (video alone condition) or video clips with sound tracks (video + sound condition). The somatosensory stimuli consisted of standard (middle finger, p =.70), target (little finger, p =.15), and nontarget (thumb, p =.15) vibratory stimuli. All the probe stimuli were presented either on the left or on the right hand. The task involved buttonpress responses to target stimuli using the other hand. Both the target and nontarget stimuli elicited a P300 wave, the amplitude of which was smaller while participants were viewing video clips than while viewing still images (picture condition). The amplitude of the nontarget P300 was further reduced by adding sound tracks to the video clips. The eventrelated potentials to somatosensory probe stimuli may be a useful objective index of how strongly an audiovisual experience attracts a viewer's attention. (Japanese Journal of Physiological Psychology and Psychophysiology, 25 (3) : 277-285, 2007.)

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The retrieval of time interval and motoric preparation during the contingent negative variation (CNV) paradigm (warning stimulus-imperative stimulus+motor response) were investigated. The participants were asked to perform the required response tasks as accurately and quickly as possible, while the inter-trial interval was varied (ITT; 3 s/10 s). The reaction time (RT), the CNV and the lateralized readiness potential (LRP), and the foreperiod-LRP (FP-LRP) were measured. Low resolution brain electromagnetic tomography (LORETA) estimated the sources of the electric current of the difference between the two conditions. The amplitude of the early CNV under the ITI-10s condition was larger than that of the ITI-3s condition over the frontal cortex, suggesting early CNV modulation as a function of the remainder of the time interval memory trace. In contrast, the amplitude of the late CNV of the ITI-3s condition was larger than that of the ITI-10s condition over the vertex of the brain. The amplitude of the FP-LRP, which seemed to increase as the memory trace was reconstructed, increased later under the ITI-10s condition compared with that under the ITI-3s condition. The LRP onset latency and the RT of the ITI-10s condition were delayed compared to those of the ITI-3s condition. In our study, the early CNV over the frontal cortex seemed to reflect the retrieval of the time interval. When the activation of the frontal cortex was larger, motoric preparation could be started relatively earlier, and reactions then seemed to be performed earlier. The estimation of the LORETA supported supplementary motor area contributes to the early CNV and precuneus and anterior cingulate to the late CNV. (Japanese Journal of Physiological Psychology and Psychophysiology, 25 (3) : 287-302, 2007.)

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