Knowing minds: Culture and perceptions of mental state access

How does culture influence the ways in which individuals reflect upon their knowledge of others’ mental states? We addressed this question in a two‐study cross‐cultural investigation examining perceptions of mental state access in the United States and Japan. Study 1 (n = 100) revealed that American participants reported greater mental state access than did Japanese participants. Study 2 (n = 146) showed that both Americans and Japanese perceived greater access to the mental states of a close friend relative to a casual friend and that the observed cultural differences in perceived mental state access to a close friend’s mental states were mediated by how much access was considered appropriate. Overall, the results indicate that culturally variable norms specifying appropriate levels of mental state access play an important role in how individuals estimate their knowledge of other people’s minds in close relationships.     

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.     

Effects of voluntary activation on neuromuscular endurance analyzed by surface electromyography

The purpose was to examine the relation between voluntary muscle activation and neuromuscular endurance of individual subjects based on the pattern of surface electromyography (EMG). The voluntary muscle activation was estimated from the relation between voluntary force and tetanic force superimposed on the voluntary force (twitch interpolation technique). 14 male subjects (10 regular exercisers and 4 sedentary; 21-29 years old) were divided into a High Voluntary Activation group and a Low Voluntary Activation group. A significant positive correlation of .72 (p<.01) was found between maximum voluntary torque and voluntary activation. A fatigue test was conducted during isometric contractions of 60% and 20% maximum voluntary torque. The endurance time was significantly longer for the Low Voluntary Activation group than the High Voluntary Activation group. The mean power frequency of voluntary EMG obtained from the vastus lateralis muscle decreased consistently whereas the average rectified value increased. The final change of mean power frequency relative to the initial value was significantly greater in the 60% Fatigue task than in the 20% Fatigue task. For the 60% Fatigue task, the final change of mean power frequency and average rectified value relative to the initial value was significantly greater in the Low Voluntary Activation group than in the High Voluntary Activation group. These results suggest that the individual differences in voluntary activation determine the neuromuscular performance usually evaluated as maximum voluntary torque and endurance time and that the voluntary activation may depend on the daily exercise.     

Influence of Deteriorating Ability of Emotional Comprehension on Interpersonal Behavior in Alzheimer-Type Dementia

This study investigated the relationship between the ability to recognize emotion and interpersonal behavior in dementia of the Alzheimer type (DAT). After examining the validity and reliability of the Emotion Recognition Test (ERT), an improved version of the tasks used by Shimokawa et al. (2000), 100 patients with DAT underwent evaluation for general cognition using the Mini-Mental State Examination (MMSE) and emotion recognition using the ERT. Within a week of these tests being administered, ward staff rated the patients using the Interpersonal Behavior Checklist (IBC), composed of two behavior scales: indifference to interpersonal relationships and difficulties with patient treatment/management. After investigating the validity and reliability of the scales, the correlations between the MMSE, the ERT, and the two scales of the IBC were calculated. The results suggested that the MMSE did not correlate with either of the two behavior scales, while the ERT correlated significantly with both of the scales. The study results lead to the conclusion that deteriorating emotion recognition ability, rather than deterioration of general cognition, influences the indifferent and awkward interpersonal behaviors of DAT patients.     

The assumed effects of positive feedback paired with success on motivation to do a task: The cases of characters with high and low initial levels of interest

This study investigated the effects of positive feedback paired with success on motivation to do a task, and examined whether this differed according to whether the person performing the task had a high or low initial level of interest in that task. Subjects (448 junior college students) were asked to rate (from 0–10) the level of motivation of characters in four different stories. Subjects believed that positive feedback would encourage the character to do a task regardless of initial level of interest. However, when positive feedback could not be expected, ratings for motivation fell. Ratings for motivation were further analyzed when no positive feedback could be expected, either after an earlier experience of positive feedback paired with success or after success only (no feedback). In the case of a low initial level of interest, it was assumed that motivation would be increased after positive feedback, but in the case of a high initial level of interest motivation was assumed to be decreased by an earlier experience of positive feedback paired with success. These results suggest that the effect of positive feedback paired with success will differ according to the level of a person's initial interest.     

Independent age cues for infancy and older age in one face: evidence for rivalry in age perception

Participants estimated the ages of infants, teens, and adults in their 20s and 60s, using averaged facial images, as well as digitally transformed images of two different age groups. Since a blended face has intermediate features of the component faces, age of the combined faces was hypothesized to be perceived as the mean age of the component faces. However, the perceived age was underestimated when the transformed face included an infant, but overestimated when the face included a person in their 60s. From this one may infer the faces of infants and adults in their 60s have strong age cues. The estimated ages for blended images of infants and adults in their 60s showed a clear bipolar distribution, with one peak at 5-9 years and the other at 50-54 years. Analysis of individual variation showed that the different response to infants-60s faces was related to variations in sensitivity to 60s faces, not to a general perceptual tendency or confused responses to ambiguous appearing faces. Thus, cues for infancy and older age are qualitatively independent and can co-exist in one face, yielding a rivalry in age perception.     

Velocity-dependent EMG activity of masseter and sternocleidomastoideus muscles during a ballistic arm thrusting movement

Two experiments were conducted to investigate the functional relationship between the general somatic motor function and the oral motor function. In Experiment 1, we analyzed the relationship between the amount of masseter muscle (MSS) activity and the velocity of a ballistic, 'karate-do' arm thrusting movement (ThrMov). ThrMov velocity was measured from video images taken with a high-speed CCD camera at a frequency of 500Hz. EMGs of MSS and sternocleidomastoideus (SCM) muscles as well as other related muscles were recorded simultaneously with video images in 6 varsity 'karate-do' athletes. Pearson's correlation coefficients were calculated between EMG amplitude and movement velocity. EMG activity of MSS as well as the other muscles increased as a function of ThrMov velocity in all participants, as evidenced by highly significant (p<.01) correlation coefficients, ranging from .64 to .87 (mean: .75). MSS EMG activity attained during ThrMovs performed at maximum velocity ranged between 14.6% and 113.8% of this muscle's MVC (45.7+/-39.3% MVC, mean+/-SD). SCM was also strongly active and closely associated with MSS. Besides changes in amount of EMG activity, it was further found that R-MSS EMG onset progressively shifted to the earlier phase of the ThrMov as ThrMov velocity increased. EMG onset time of R-MSS as well as R- and L-SCMs was negatively correlated with ThrMov velocity; when performed at maximum velocity MSS activation preceded the start of ThrMov by more than 100ms, whereas MSS was recruited last at approximately 150ms after the start of ThrMov when performed at moderate speed ( approximately 50% of maximum). In Experiment 2, the effects of head movement relative to the trunk on R-MSS and SCMs EMG activity were tested in both gazing and sidelong glancing conditions. A much smaller head rotation relative to the trunk was necessary during the ThrMov in the sidelong glancing condition compared to the gazing condition. R-MSS EMG activity was affected significantly by the difference between these conditions and decreased by 5.2% MVC in the sidelong glancing condition compared to the gazing condition. In association with the change in requirement for head movement between those conditions, EMG balance between the bilateral SCMs changed substantially. Finally, marked muscle activity during ThrMov was found in the MSS that was not directly involved in performing this movement, indicating a form of 'remote facilitation'.