Neuroticism, extraversion, and related traits in adult twins reared apart and reared together

The relative importance of genetic and environmental factors for neuroticism, extraversion, impulsivity, and monotony avoidance were estimated in a sample of 99 monozygotic and 229 dizygotic pairs of twins reared apart (TRA) and a matched sample of 160 monozygotic and 212 dizygotic pairs of twins reared together (TRT). The average age was 58.6 (SD = 13.6); 72% of the twins were 50 or older. Model-fitting analyses verified the importance of genetic factors for all four measures; from 23% to 45% of the total variation was attributable to genetic sources. There was considerable evidence that these factors were operating in a nonadditive manner for extraversion and impulsivity. Shared environment accounted for less than 10% of the variance; some evidence for selective placement was found for neuroticism.     

Influence of positive affect on the subjective utility of gains and losses: it is just not worth the risk

A modification of the procedure originally used by Davidson, Suppes, and Siegel (1956) to measure subjective utility was used to study the influence of positive affect on individuals' perceived value (utility) functions. Results indicated, as expected, that persons in whom positive affect had been induced showed a more negative subjective utility for losses than did controls. This indicates that losses seem worse to people who are feeling happy than to those in a control condition. The subjective utility functions of the two groups did not differ as much, however, when people were considering potential gain. Thus, at least in the situation tested in this study, potential gains did not seem to be more appealing (nor less so) for affect subjects than they did for controls. These findings are discussed in relation to theoretical issues in decision making and work suggesting that positive affect can promote increased sensitivity to losses in situations of potential meaningful loss.     

The recognition of threatening facial stimuli

Two studies examined the information that defines a threatening facial display. The first study identified those facial characteristics that distinguish between representations of threatening and nonthreatening facial displays. Masks that presented either threatening or nonthreatening facial displays were obtained from a number of non-Western cultures and scored for the presence of those facial features that discriminated between such displays in the drawings of two American samples. Threatening masks contained a significantly higher number of these characteristics across all cultures examined. The second study determined whether the information provided by the facial display might be more primary nonrepresentational visual patterns than facial features with obvious denotative meaning (e.g., diagonal lines rather than downturned eyebrows). The subjective response to sets of diagonal, angular, and curvilinear visual stimuli revealed that the nonrepresentational features of angularity and diagonality in the visual stimulus appeared to have the ability to evoke the subjective responses that convey the meaning of threat.     

The sociobiology of bereavement: a reply to Littlefield and Rushton

This article offers a critique of Littlefield and Rushton's (1986) application of sociobiological principles to bereavement following the death of a child. The following general issues are considered: (a) whether behavior is always adaptive and (b) the distinction between proximate and ultimate explanations. It is argued that grief is a maladaptive by-product of another, adaptive feature and that hypotheses about the severity of grief are best derived from proximate considerations rather than genetic relatedness. The use of a single-item rating scale to measure grief is questioned, and it is noted that interspouse reliabilities reported in the article were low, a problem not solved (as claimed) by aggregation. Criticisms are made of the specific hypotheses, notably in terms of their origins in sociobiological theory. It is argued that functional hypotheses are not alternatives to proximate mechanisms, but enable some proximate mechanisms to be viewed from the perspective of evolutionary biology.     

Spontaneous covariations of movement parameters in 5- to 7-year-old boys

The kinematic parameters of to and fro forearm movements in the horizontal plane were investigated in 5- to 7-year-old boys. In one condition, the period of the movements was induced by an acoustic stimulus, while the amplitude was left free. In a second condition, the amplitude of the swing was suggested by a visual frame, but the movement was self-paced. In both conditions, the unconstrained variable (amplitude and period, respectively) was found to covary spontaneously with the constrained variable. The results suggest that, within the age range considered here, motor control processes do not conceive of amplitude and velocity as two independent variables.     

The role of visual information in control of a constrained locomotor task

The nature of visually guided locomotion was examined in an experiment where subjects had to walk to targets under various conditions. Target distance was manipulated so that subjects had to (a) lengthen their paces in order to hit the target; (b) shorten their paces; (c) make no adjustments to their standard pace length at all. They did this under four visual conditions: (a) normal vision; (b) with vision restricted to a "snapshot" each time the foot that was to be placed on the target was on the ground; (c) with a snapshot each time the foot to be placed was in the swing phase; and (d) no vision after departure fro the target. The results show that the subjects succeed in reaching the target in most cases. However, the smoothness and fluidity of their movements vary significantly between conditions. Under normal vision or where visual snapshots are delivered when the pointing foot is on the ground, locomotion is smoothly regulated as the subjects approach the target. where snapshots are delivered when the pointing foot is in the swing phase, regulation becomes clumsy and ill coordinated. Where no vision is available at all during the approach, adjustments are made, but these are least coordinated of all. The results show that well-coordinated visual regulation does not require continuous visual guidance but depends on intermittent information being available at the appropriate times in the action sequence. Such timing is often more important than the total amount of information that is available for guidance.     

Specific forms of facial EMG response index emotions during an interview: from Darwin to the continuous flow hypothesis affect-laden information processing

Previous research has demonstrated that mild negative emotional imagery and unpleasant sensory stimuli lead to greater electromyographic activity over the brow muscle region than mild positive imagery and stimuli, even in the absence of significant changes in visceral and general facial EMG activity. Previous research has not addressed whether electromyographic responses over the brow region are a sensitive and specific index of emotions, however, since a multiplicity of events lead to changes in brow activity. In this research, facial electromyographic and audiovisual recordings were obtained while individuals were interviewed about themselves. Afterwards, individuals were asked to describe what they had been thinking of during specific segments of the interview marked by distinctive electromyographic responses over the brow region in the context of ongoing but stable levels of activity elsewhere in the face. The results are interpreted in terms of a continuous flow hypothesis of affect-laden information processing.     

Mood, memory, and social judgments in children

The influence of positive and negative moods on children's recall and recognition memory and impression-formation judgments was investigated in a two-list experimental design. A total of 161 schoolchildren, 8 to 10 years old, were presented with audiovisual information containing positive and negative details about 2 target children. Each presentation was preceded by happy or sad mood manipulations. One day later, the children were again placed in a happy or sad mood, and their recall and recognition memory and impression-formation judgments were assessed. Results showed that memory was better when (a) the children felt happy during encoding, retrieval, or both; (b) the material was incongruent with learning mood; (c) the 2 target characters were encountered in contrasting rather than in matching mood states; and (d) recall mood matched encoding mood. A happy mood increased the extremity of both positive and negative impression-formation judgments. Results are contrasted with experimental data obtained with normal or depressed adults, and implications are considered for contemporary theories of mood effects on cognition and for social-developmental research.     

Impressions of people created by age-related qualities of their gaits

Drawing on the ecological theory of social perception, we investigated the impact of age-related gait qualities on trait impressions. In Study 1, subjects observed 5- to 70-year-old walkers depicted in point-light displays, and rated the walkers' traits, gaits, and ages. Younger walkers were perceived as more powerful and happier than older walkers. A composite of youthful gait qualities predicted trait impressions regardless of the walkers' masculine gait qualities, sex, and perceived age. In Study 2, subjects observed young adult walkers depicted in point-light displays and rated their traits, gaits, and ages. Consistent with the effects of real age found in Study 1, young adults with youthful gaits were perceived as more powerful and happier than peers with older gaits, irrespective of their masculine gait qualities, sex, and perceived age. Study 3 replicated Study 2 using displays showing walkers' full bodies and faces. A youthful gait predicted trait impressions even when subjects could discern the walkers' age and sex.