Recently, baroreceptor reflex sensitivity (BRS) has been the focus of much attention as a noninvasive index of cardiac vagal activity. BRS is known to be suppressed in the defense reaction and is expected to be so in active coping. In this study, two mental arithmetic tasks were employed as active coping, and suppression of BRS was assessed. Namely, a group of 13 undergraduates executed serial subtraction, and another 13 answered arithmetic questions on a computer display. These two tasks were classified as internally vs. externally generative type (IGT vs. EGT), based on the nature of the stimulus presentation. Systolic blood pressure (SBP) and heart rate (HR) were measured continuously, and BRS was calculated from SBP recordings by the sequence scanning method (Bertinieri et al., 1985).
Results indicated that in the IGT task, a significant suppression of BRS took place, though moderate elevations of SBP and HR were observed. In contrast, in the EGT task a tendency of suppression of BRS was accompanied by remarkable elevations of SBP and HR.
These contradictory results were attributable to the subjects paying greater attention to the external stimulus in the EGT task than the internal stimulus of the IGT task.

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Autonomic response specificity refers to a patterning of autonomic variables according to a particular stimulus. The present study investigated the autonomic response patterns elicited during the viewing of video-taped stimuli selected to produce positive and negative emotions in the viewer. Neutral footage, designed not to provoke any emotional state, was also used. Fifteen participants successively viewed three 10-minute films; blood pressure (BP), electrocardiogram, fingertip temperature and respiration rate were measured throughout the viewing of the films. The participants completed two questionnaires after each film presentation. The questionnaires concerned the emotions that were provoked by the films. Once the provoked emotions were identified by the questionnaires the physical findings were analyzed; cardiovascular responses decreased during positive and increased during negative emotion. Fingertip temperature increased during negative emotions but did not change during positive emotions. From a hemodynamics viewpoint, the increase in BP resulted from an increase in the peripheral vascular resistance (PVR) and heart rate. Based on the cognitive aspects of the responses to the film stimuli, the different cardiovascular patterns during positive and negative emotions were explained by the stimulus intake-rejection hypothesis; i.e., cardiovascular response increases during information intake and decreases during information rejection. In conclusion, autonomic response specificity patterns may be detected among different cardiovascular response patterns using emotion-inducing stimuli.

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Dream reports are obtained with a high percentage from REM (rapid eye movement) sleep awakening. However, it is not clear when the recalled dream experience actually occurred. To specify sleep states when dream occurs, we controlled sleep duration and examined the relationship between dream reports and sleep variables, using an ultra-short sleep-wake schedule. Eleven healthy males (22.7 ± 1.44 years) participated in the study. Twentymin Polysomnographic recordings (nap trials) were repeated every hour for 78 hour. A structured interview assessed formal aspects of dream (quantity, vividness, comfortableness and uncomfortableness) was performed at the end of each nap. We obtained 172 nap trials including REM sleep (REM trials) and 563 nap trials including only NREM sleep (NREM trials). Dream report was obtained from 51.2% of REM trials, while it was obtained from 17.9% of NREM trials. Scores of dream quantity, vividness and comfortableness in the REM trials were higher than those in the NREM trials. These results suggest that occurrence of dream experiences is higher in REM sleep than in NREM sleep, and confirm that dream experiences can occur in NREM sleep even when effects of the prior REM sleep are experimentally eliminated.

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Recent studies have reported that there is a component of the event-related brain potential, an error-related negativity (ERN), that is related to error detection in choice reaction time tasks. The present study examined whether or not the ERN reflects mental resource allocated to error detection using the single and dual tasks. Only Eriksen flanker task was used in the single task condition. Eriksen flanker task was used as a primary task and an auditory choice reaction time task was used as a secondary task in the dual task conditions. In addition, we manipulated the task difficulty of the secondary task. In comparison with the single task, reaction time was delayed and the ERN amplitude decreased in the primary task as the secondary task difficulty increased in the dual task. This suggests that the error detection process in the primary task may diminish when the secondary task requires more perceptual resource. In conclusion, the reduced perceptual resource influenced the error detection process for the primary task revealing the reduced ERN.

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This study examined the effects of a mental countermeasure on the Guilty Knowledge Test (GKT) by P3. Twenty-eight subjects enacted a mock crime in which they stole one of five jewels in the pouch. The subjects were randomly divided into two groups : a countermeasure (CM) group and a non-countermeasure (NCM) group. In the GKT, each picture of five jewels was presented on a CRT display and the subjects were required to press a button as soon as they recognized the stimulus. In addition, only the CM group was instructed to count backwards in si-lent by sevens from 200 during the experiment. The results showed that P3 amplitudes to the relevant stimuli from Cz and Pz were smaller in the CM group than in the NCM group, although P3 amplitudes to the relevant stimuli were consistently larger than to the irrelevant stimuli. The correct detection rate was 50% in the CM and 79% in the NCM group. These findings indicate that GKT by P3 is immune from the effects of the countermeasure.

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The present study investigated peripheral skin blood flow, measured by laser-Doppler flowmetry, as a new potential index in detection of deception. Eighteen undergraduates were instructed to “steal” a colored envelope containing a piece of jewelry and to hide it. The participants were then presented with questions focusing on the color of the envelope they stole and were requested to answer “no” to every question. Blood flow of fingertip and amplitude of skin conductance response (SCR) were measured after the onset of the question. Transient decreases in the blood flow were observed in critical items as well as in non-critical items. However, the blood flow significantly decreased more in the critical items. The decrement was most distinctive about 6 to 15 seconds after the onset of the critical items. It was indicated that the blood flow decreased in critical items even in the participants who did not show significant differences in SCR between critical and non-critical items. The present study showed the efficacy of blood flow, measured by laser-Doppler flowmetry, as an index in psychophysiological detection of deception.

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This study investigated the effect of habitual self-awakening on nocturnal sleep. Thirteen subjects who habitually self-awaken in the morning participated in two experimental nights; forced-awakening night and selfawakening night. In forced-awakening night, subjects were forced to be awaken by the experimenter at the time when they usually awake. In self-awakening night, subjects attempted to self-awaken at the time when they usually awake. Their anxiety immediately before the experimental nights, polysomnography during the nights, and the subjective ratings of sleep immediately after awake were analyzed. The subjects succeeded self-awakening in 8 of 19 self-awakening nights (42.1%). There were no significant differences between the forced-and self-awakening nights in their anxiety, subjective ratings of sleep, and sleep variables, except for the amount of stage 1. These results suggest that habitual self-awakening have no negative effects on nocturnal sleep, mood after awake, and satisfaction in sleep.

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[in Japanese]

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