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.     

Conceptions of states and traits: dimensional attributes with ideals as prototypes

Traits and states are concepts that people use to both describe and understand themselves and others. We show that people view these concepts as prototype-based categories that have a graded internal structure and fuzzy boundaries and identify a set of attributes that define the prototypical cores of two categories: traits and states. Prototypical traits are stable, long-lasting, and internally caused. Prototypical states are temporary, brief, and caused by external circumstances. These prototypes are not defined by averages, as the family-resemblance principle would suggest, but by ideal (or extreme) attribute values. Like other ideal-based categories, traits and states serve particular goals. Trait concepts permit people to predict the present from the past; state concepts identify those behaviors that can be controlled by manipulating the situation. These two complementary schemas are part of the extensive theory of psychological causality that is implicit in language. Abstract social concepts differ from object categories in their category standards, the nature of their attributes, and the interrelations among those attributes.     

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.     

Role of visual information in ball catching

The present study is concerned with the perceptual information about the body and space underlying the act of catching a ball. In a series of four experiments, subjects were asked to catch a luminous ball under various visual conditions. In general, catching in a normally illuminated room was contrasted with catching the luminous ball in an otherwise completely dark room. In the third and fourth experiments, intermediate conditions of visual information were included. The results suggest that it is possible to catch a ball with one hand when only the ball is visible, but performance is better when the subject has the benefit of a rich visual environment and two hands. The second experiment indicated that subject performance does improve with practice in the dark, but time spent in the darkened room itself doesn't result in a significant decrement in performance. Results of the third study suggest that vision of one's hand does not aid in the performance of this task whereas the presence of a minimal visual frame appears to aid performance. The final study examined the relation between catching performance and body sway under similar visual conditions. Results of this experiment imply that persons who exhibit relatively little postural sway in full-room lighting performed better at this catching task.     

The development of locomotor coordination: longitudinal change and invariance

Developmental sequence, relative timing, center of gravity, and phase-plane analyses were used to study a minimum of 15 years of longitudinal, filmed data on the development of hopping in 7 children. The developmental sequences revealed common, qualitative changes in the movement of the children, although each child progressed through the changes at his/her own rate. The timing analyses showed that, in the advanced hop, the tightest limb relationships were found within the hopping leg, then between contralateral limbs of the same girdle, and then between legs and arms. Relative-timing calculations revealed (a) intralimb, timing invariances that were present in first attempts to perform the skill at age 3 and remained for 15 years across all developmental levels; (b) emergent, interlimb timings that gradually became invariant; and (c) intra- and interlimb timing showing gradual development over the 15 years. One invariant, the time between landing and deepest knee flexion, is also invariant in the walk and the run (Shapiro, Zernicke, Gregor, & Diestel, 1981). Phase plane analyses indicated that the timing of peak and zero velocities may be the coordinative constant accounting for a relative timing invariance between the two legs. Position of the body's center of gravity may explain the invariant relative time between landing and deepest knee flexion, or the explanation could lie in the "equation of constraint" regulating joint equilibrium points. The data suggest that modeling the developing hop as the evolving interaction of four vibratory systems would be promising.     

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.     

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.     

Marital conflict and adjustment: speech nonfluencies in intimate disclosure

Speech nonfluency in response to questions about the marital relationship was used to assess anxiety. Subjects were 31 husbands and 31 wives, all white, college educated, from middle- to lower-middle-class families, and ranging from 20 to 30 years of age. Three types of nonfluencies were coded: filled pauses, unfilled pauses, and repetitions. Speech-disturbance ratios were computed by dividing the sum of speech nonfluencies by the total words spoken. The results support the notion that some issues within marriage are more sensitive and/or problematic than others, and that, in an interview situation, gender interacts with question content in the production of nonfluencies.     

Perceptual sensitivity to dimensional and similarity relations in free and rule-governed classifications

Two experiments were conducted to investigate the perceptual primacy of dimensional and similarity relations in the stimulus classifications of younger and older subjects. In Experiment 1, 4- and 10-year-olds were given free classifications in which they could group stimuli according to overall similarity or identities in size, color, or orientation. Both age groups classified stimuli most frequently according to identities on separate dimensions. In Experiment 2, 4-year-olds and adults were given free classifications followed by rule-governed classifications which required them to group stimuli according to specific relations. In the free classifications, a majority of subjects in both age groups classified the stimuli most frequently according to identities on separate dimensions. In the rule-governed classifications, both age groups were more accurate when a single separate relation was required for solution than when overall similarity was required. These results support a differential-sensitivity view of perceptual development, which asserts that individuals at all ages primarily perceive and use separate relations.