Atsunobu Suzuki

Is the genetic structure of human personality universal? A cross-cultural twin study from North America, Europe, and Asia.

This study examined whether universality of the 5-factor model (FFM) of personality operationalized by the Revised NEO Personality Inventory is due to genetic influences that are invariant across diverse nations. Factor analyses were conducted on matrices of phenotypic, genetic, and environmental correlations estimated in a sample of 1,209 monozygotic and 701 dizygotic twin pairs from Canada, Germany, and Japan. Five genetic and environmental factors were extracted for each sample. High congruence coefficients were observed when phenotypic, genetic, and environmental factors were compared in each sample as well as when each factor was compared across samples. These results suggest that the FFM has a solid biological basis and may represent a common heritage of the human species.

GENETIC AND ENVIRONMENTAL STRUCTURE OF CLONINGER'S TEMPERAMENT AND CHARACTER DIMENSIONS

The multivariate genetic and environmental structure of Cloningers Temperament and Character Inventory (TCI) was investigated in a sample of 617 pairs of adolescent and young adult twins from Japan. Additive genetic factors accounted for 22% to 49% of the variability on all TCI temperament scales. Although the theory predicts lower heritability for the character scales, all character subscales had a substantial genetic contribution, and nonshared environmental influences accounted for the remainder. Multivariate genetic analyses showed that several subscales used to define one dimension shared a common genetic basis with subscales defining others. Using the degree of shared genetic influence as the basis to rearrange the TCI subscales into new dimensions, it was possible to create genetically independent scales. The implications for personality measurement, theory, and molecular genetic research are discussed.

Decline or improvement? Age-related differences in facial expression recognition

We examined age-related differences in facial expression recognition in association with potentially interfering variables such as general cognitive ability (verbal and visuospatial abilities), face recognition ability, and the experiences of positive and negative emotions. Participants comprised 34 older (aged 62-81 years) and 34 younger (aged 18-25 years) healthy Japanese adults. The results showed not only age-related decline in sadness recognition but also age-related improvement in disgust recognition. Among other variables, visuospatial ability was moderately related to facial expression recognition in general, and the experience of negative emotions was related to sadness recognition. Consequently, age-related decline in sadness recognition was statistically explained by age-related decrease in the experience of negative emotions. On the other hand, age-related improvement in disgust recognition was not explained by the interfering variables, and it reflected a higher tendency in the younger participants to mistake disgust for anger. Possible mechanisms are discussed in terms of neurobiological and socio-environmental factors.

Application of the somatic marker hypothesis to individual differences in decision making.

The somatic marker hypothesis (Damasio, Tranel, & Damasio, 1991) is a controversial theory asserting that somatic activities implicitly bias human behavior. In this study, we examined the relationship between choice behaviors in the Iowa Gambling Task and patterns of skin conductance responses (SCRs) within a healthy population. Results showed that low SCRs for appraising the monetary outcome of risky decisions were related to persistence in risky choices. Such adherence to risky decisions was not related to poor explicit knowledge about the task. On the other hand, anticipatory SCRs and the effect of them on performance were not confirmed. Our findings suggest that a variation in covert physiological appraisal underlies individual differences in decision making.

Enhanced memory for the wolf in sheep’s clothing:: Facial trustworthiness modulates face-trait associative memory

Our decision about whether to trust and cooperate with someone is influenced by the individuals facial appearance despite its limited predictive power. Thus, remembering trustworthy-looking cheaters is more important than remembering untrustworthy-looking cheaters because we are more likely to trust and cooperate with the former, resulting in a higher risk of unreciprocated cooperation. The present study investigated whether our mind adaptively copes with this problem by enhancing memory for trustworthy-looking cheaters. Participants played a debt game, wherein they learned to discriminate among good, neutral, and bad lenders, who respectively charged no, moderate, and high interest on the debt. Each lender had either a trustworthy- or untrustworthy-looking face. A subsequent memory test revealed that participants remembered the bad traits of trustworthy-looking lenders more accurately than those of untrustworthy-looking lenders. The results demonstrate enhanced memory for trustworthy-looking cheaters, or wolves in sheeps clothing, implying that humans are equipped with protective mechanisms against disguised, unfaithful signs of trustworthiness.

Cognitive aging explains age-related differences in face-based recognition of basic emotions except for anger and disgust

ABSTRACT This study aimed at a detailed understanding of the possible dissociable influences of cognitive aging on the recognition of facial expressions of basic emotions (happiness, surprise, fear, anger, disgust, and sadness). The participants were 36 older and 36 young adults. They viewed 96 pictures of facial expressions and were asked to choose one emotion that best described each. Four cognitive tasks measuring the speed of processing and fluid intelligence were also administered, the scores of which were used to compute a composite measure of general cognitive ability. A series of hierarchical regression analyses revealed that age-related deficits in identifying happiness, surprise, fear, and sadness were statistically explained by general cognitive ability, while the differences in anger and disgust were not. This provides clear evidence that age-related cognitive impairment remarkably and differentially affects the recognition of basic emotions, contrary to the common view that cognitive aging has a uniformly minor effect.

Facial emotion recognition and cerebral white matter lesions in myotonic dystrophy type 1

In order to investigate the cognitive and neurological bases of social cognitive impairment in myotonic dystrophy type 1 (DM1), we examined the facial expression recognition abilities and the cerebral lesions in a group of DM 1 (5 men, 4 women). We measured sensitivity to facial emotions and compared the findings with magnetic resonance image (MRI) findings evaluated using a semi-quantitative method. The DM1 patients showed lower sensitivity to disgusted and angry faces as compared to the healthy controls. The assessment of brain lesions revealed that more severe lesions occurred in the frontal, temporal, and insular white matters. Sensitivity to the emotion of disgust was negatively correlated with temporal lesions, and sensitivity to anger negatively correlated with frontal, temporal, and insular lesions. The results of this study indicate an association between lesions in the frontal, temporal, and insular subcortices and decreased emotional sensitivity to disgust and anger in DM1 patients. These areas are thought to play an important role in emotional processing in the normal brain. Our results suggest that social cognitive impairment in DM1 patients is attributable to impaired emotional processing linked to white matter lesions.

Lowered sensitivity to facial emotions in myotonic dystrophy type 1.

BACKGROUND It has been observed that patients with myotonic dystrophy type 1 (DM1) exhibit social-cognitive impairment. However, the cognitive and neurological bases of the social-cognitive impairment in DM1 have not been adequately investigated. METHODS We studied cognitive deficits and impairment in facial expression recognition in two DM1 patients (one man and one woman). We measured the sensitivity of these patients to basic emotions and compared the results with those from magnetic resonance imaging and single photon emission computed tomography. RESULTS The DM1 patients showed lower sensitivity to fearful, disgusted, and angry faces than did the healthy controls. They also had lesions in the anterior temporal white matter, the amygdala, and the insular and orbitofrontal cortices. CONCLUSION The results of this study revealed that the DM1 patients had subcortical lesions in the anterior temporal areas, including the amygdala and the insular and orbitofrontal cortices. The limbic system, which includes these areas of the brain, plays an important role in emotional processing. Hence, the social-cognitive impairment in DM1 patients could be associated with a decreased sensitivity to facial expressions owing to lesions in the limbic system.

Sustained happiness? Lack of repetition suppression in right-ventral visual cortex for happy faces

Emotional stimuli have been shown to preferentially engage initial attention but their sustained effects on neural processing remain largely unknown. The present study evaluated whether emotional faces engage sustained neural processing by examining the attenuation of neural repetition suppression to repeated emotional faces. Repetition suppression of neural function refers to the general reduction of neural activity when processing a repeated stimulus. Preferential processing of emotional face stimuli, however, should elicit sustained neural processing such that repetition suppression to repeated emotional faces is attenuated relative to faces with no emotional content. We measured the reduction of functional magnetic resonance imaging signals associated with immediate repetition of neutral, angry and happy faces. Whereas neutral faces elicited the greatest suppression in ventral visual cortex, followed by angry faces, repetition suppression was the most attenuated for happy faces. Indeed, happy faces showed almost no repetition suppression in part of the right-inferior occipital and fusiform gyri, which play an important role in face-identity processing. Our findings suggest that happy faces are associated with sustained visual encoding of face identity and thereby assist in the formation of more elaborate representations of the faces, congruent with findings in the behavioral literature.

Indelible distrust: Memory bias toward cheaters revealed as high persistence against extinction

Our ability to learn about the reputations of others-that is, who is likely to cooperate versus cheat-contributes greatly to cooperativeness in society. There has been recent debate whether humans employ memory bias favoring cheaters (i.e., there is an evolved module for the detection of cheaters) or whether no such bias exists (i.e., reputation learning is flexibly modulated by contextual factors). We report 3 experiments that address this issue by comparing persistence against extinction-which is a reliable measure of prepared fear learning (Öhman & Mineka, 2001)-between memories regarding cheaters and cooperators. In all experiments, participants learned to classify unfamiliar persons as either cooperators or cheaters, and, then, they were instructed to disregard those learned associations and told that they had been determined arbitrarily, which simulated a verbal extinction procedure in the fear conditioning paradigm (Hugdahl & Öhman, 1977). The results indicated that while postlearning changes in perceived trustworthiness were modulated by a contextual factor (appearance of the facial stimulus), the persistence of learning exhibited a cheater advantage: Cheaters remained perceived as untrustworthy to a greater extent than cooperators as trustworthy at the extinction period. Thus, there exists a cheater bias in human reputation learning, the proximate and ultimate mechanisms of which warrant further study.