From mouth to hand: gesture, speech, and the evolution of right-handedness

The strong predominance of right-handedness appears to be a uniquely human characteristic, whereas the left-cerebral dominance for vocalization occurs in many species, including frogs, birds, and mammals. Right-handedness may have arisen because of an association between manual gestures and vocalization in the evolution of language. I argue that language evolved from manual gestures, gradually incorporating vocal elements. The transition may be traced through changes in the function of Broca's area. Its homologue in monkeys has nothing to do with vocal control, but contains the so-called "mirror neurons," the code for both the production of manual reaching movements and the perception of the same movements performed by others. This system is bilateral in monkeys, but predominantly left-hemispheric in humans, and in humans is involved with vocalization as well as manual actions. There is evidence that Broca's area is enlarged on the left side in Homo habilis, suggesting that a link between gesture and vocalization may go back at least two million years, although other evidence suggests that speech may not have become fully autonomous until Homo sapiens appeared some 170,000 years ago, or perhaps even later. The removal of manual gesture as a necessary component of language may explain the rapid advance of technology, allowing late migrations of Homo sapiens from Africa to replace all other hominids in other parts of the world, including the Neanderthals in Europe and Homo erectus in Asia. Nevertheless, the long association of vocalization with manual gesture left us a legacy of right-handedness.     

Dominance,aggression, and the functional use of space in institutionalized female adolescents

This is a study of an institutionalized group of female adolescents observed for a nine-week period. These girls were observed to determine the characteristics of their dominance relations and how, in turn, this aspect of their social environment was related to use of their physical environment. Correlational analyses between observational and sociometric data suggested that dominance rank was based upon the frequency of being the recipient of a dominance act. Fewer dominance acts were initiated against higher ranking girls. Dominance ranking was not based upon frequency of initiating a dominance act towards others. Higher ranking girls were the ones most frequently observed alone in their own bedroom. Bedrooms were highly desiuable areas used for grooming (eg, setting hair, ironing clothes, putting on cosmetics, resting) as girls sought to gain popularity with the institution's male population. Comparison of results with findings in similar studies on male adolescents suggest some tentative generalizations as to sex difference in dominance and territoriality.     

Predicting the use of corporal punishment: Child aggression,parent religiosity,and the BDNF gene

Corporal punishment (CP) has been associated with deleterious child outcomes, highlighting the importance of understanding its underpinnings. Although several factors have been linked with parents’ CP use, genetic influences on CP have rarely been studied, and an integrative view examining the interplay between different predictors of CP is missing. We focused on the separate and joint effects of religiosity, child aggression, parent's gender, and a valine (Val) to methionine (Met) substitution in the brain‐derived neurotrophic factor (BDNF) gene. Data came from a twin sample (51% male, aged 6.5 years). We used mothers’ and fathers’ self‐reports of CP and religiosity, and the other parent's report on child aggression. Complete data were available for 244 mothers and their 466 children, and for 217 fathers and their 409 children. The random split method was employed to examine replicability. For mothers, only the effect of religiosity appeared to replicate. For fathers, several effects predicting CP use replicated in both samples: child aggression, child sex, religiosity, and a three‐way (GxExE) interaction implicating fathers’ BDNF genotype, child aggression and religiosity. Religious fathers who carried the Met allele and had an aggressive child used CP more frequently; in contrast, secular fathers’ CP use was not affected by their BDNF genotype or child aggression. Results were also repeated longitudinally in a subsample with age 8–9 data. Findings highlight the utility of a bio‐ecological approach for studying CP use by shedding light on pertinent gene‐environment interaction processes. Possible implications for intervention and public policy are discussed.

     

Psychopathy and aggression: Examining the role of psychopathy factors in predicting laboratory aggression under hostile and instrumental conditions

Psychopathy is a problematic configuration of traits and behaviors that is consistently correlated with aggressive, criminal behavior. Studies have suggested that psychopathy is composed of related but distinct factors that manifest divergent relations with a host of constructs including aggression. In the current study, we used a sample of 126 men to examine whether these psychopathy factors are differentially related to aggression manifested in two conditions (instrumental and hostile/reactive aggression) of a laboratory aggression paradigm. Traits related to an antagonistic interpersonal style and emotional detachment (i.e., Factor 1) were related to aggression in both conditions whereas traits related to negative emotionality, impulsivity, and an antagonistic style (i.e., Factor 2) were related to aggression only in the hostile/reactive condition. Potential explanations for these findings are put forth.     

Alcohol expectancies, alcohol use, and hostility as longitudinal predictors of alcohol-related aggression

The direct and interactive effects of alcohol expectancies for aggression, dispositional hostility, and heavy alcohol consumption on alcohol-related physical aggression were examined across the first four years of marriage in a sample of 634 newlywed couples. For husbands, alcohol aggression expectancies predicted increases in alcohol-related aggression; across husbands and wives, however, aggression expectancies were not found to interact with hostility or alcohol consumption to predict physical aggression. Consistent with previous research, hostility and alcohol consumption interacted with each other to predict alcohol-related aggression. Specifically, for both husbands and wives high in dispositional hostility, heavy alcohol consumption was positively associated with the occurrence of alcohol-related aggression; for those low in dispositional hostility, however, there was no association between alcohol consumption and alcohol-related aggression. Findings are contrasted with previous longitudinal research on alcohol aggression expectancies and physical aggression in married couples. The article discusses the extent to which findings may vary depending on whether expectancies are assessed in relation to alcohol's effect on one's own behavior versus alcohol's effect on others' behavior.     

The effects of elimination of hand gestures and of verbal codability on speech performance

Subjects were required to describe line drawings of two-dimensional shapes at two levels of verbal codability, with and without using hand gestures. Elimination of gesture affected speech performance by changing the semantic content of utterances and the proportion of speaking time spent pausing; numbers of words, numbers of pauses, mean pause length and semantic content were found to be related to the verbal codability of the stimulus material; and the number of hesitations was related to both gesture and level of codability.     

A meta-analytic review of gender variations in children's language use: talkativeness, affiliative speech, and assertive speech

Three sets of meta-analyses examined gender effects on children's language use. Each set of analyses considered an aspect of speech that is considered to be gender typed: talkativeness, affiliative speech, and assertive speech. Statistically significant average effect sizes were obtained with all three language constructs. On average, girls were slightly more talkative and used more affiliative speech than did boys, whereas boys used more assertive speech than did girls. However, the average effect sizes were either negligible (talkativeness, d=0.11; assertive speech, d=0.11) or small (affiliative speech, d=0.26). Larger effect sizes were indicated for some language constructs depending on either the operational definition of the language measure, the method of recording, the child's age level, the interaction partner (adult or peer), group size, gender composition, observational setting, or type of activity. The results are interpreted in relation to social-developmental and social-constructionist approaches to gender; these views are presented as complementary--rather than competing--meta-theoretical viewpoints.     

The structure of self-reported aggression, drug use, and delinquent behaviors during early adolescence

Examined the structure of self-report scales designed to assess the frequency of adolescent problem behaviors. Urban (n = 988) and rural (n = 1,895) middle school students completed the Problem Behavior Frequency Scale (Farrell, Danish, & Howard, 1992a) and measures of other relevant constructs. Confirmatory factor analyses supported a model that included specific factors related to aggression, drug use, and delinquent behaviors, and a higher order problem behavior factor. Findings did not support a distinction between physical and nonphysical aggression. Results were generally consistent across settings (i.e., urban vs. rural) and gender. Other relevant constructs, including peer pressure for drug use and attitudes favoring aggression, had both specific associations with relevant first-order factors and more general associations with the second-order factor. These findings support the construction of separate scales assessing specific domains of problem behaviors in studies of adolescents' problem behaviors.     

A meta-analytic review of gender variations in adults' language use: talkativeness, affiliative speech, and assertive speech.

Three separate sets of meta-analyses were conducted of studies testing for gender differences in adults' talkativeness, affiliative speech, and assertive speech. Across independent samples, statistically significant but negligible average effects sizes were obtained with all three language constructs: Contrary to the prediction, men were more talkative (d = -.14) than were women. As expected, men used more assertive speech (d = .09), whereas women used more affiliative speech (d = .12). In addition, 17 moderator variables were tested that included aspects of the interactive context (e.g., familiarity, gender composition, activity), measurement qualities (e.g., operational definition, observation length), and publication characteristics (e.g., author gender, publication source). Depending on particular moderators, more meaningful effect sizes (d > .2) occurred for each language construct. In addition, the direction of some gender differences was significantly reversed under particular conditions. The results are interpreted in relation to social-constructionist, socialization, and biological interpretations of gender-related variations in social behavior.     

Neuropsychological functions of hand movements and gestures change in the presence or absence of speech

In order to address previous controversies whether hand movements and gestures are linked to mental concepts or solely to the process of speaking, in the present study we investigate the neuropsychological functions of the entire spectrum of unimanual and bimanual hand movements and gestures when they either accompany speaking or when they act as the only means to communicate in the absence of speech. The results showed that the hand movement activity regarding all types of hand movements and gestures stayed constant with and without speaking. The analysis of the Structure of hand movements showed that executions shifted from in space hand movements with a phase structure during the condition without speech to more irregular on body hand movements without a phase structure during the co-speech condition. The gestural analysis revealed that pantomime gestures increase under conditions without speech whereas emotional motions and subject-oriented actions primarily occur when speaking. The present results provide evidence that the overall hand movement activity does not differ between co-speech conditions and conditions without speech, but that the hands adopt different neuropsychological functions. We conclude that the hands primarily externalise mental concepts in conditions without speaking but that their use shifts to more self-regulation and to endorsing verbal output with emotional connotations when they accompany speech.     

The effect of SpeechEasy on stuttering frequency, speech rate, and speech naturalness

The effects of SpeechEasy on stuttering frequency, stuttering severity self-ratings, speech rate, and speech naturalness for 31 adults who stutter were examined. Speech measures were compared for samples obtained with and without the device in place in a dispensing setting. Mean stuttering frequencies were reduced by 79% and 61% for the device compared to the control conditions on reading and monologue tasks, respectively. Mean severity self-ratings decreased by 3.5 points for oral reading and 2.7 for monologue on a 9-point scale. Despite dramatic reductions in stuttering frequency, mean global speech rates in the device condition increased by only 8% in the reading task and 15% for the monologue task, and were well below normal. Further, complete elimination of stuttering was not associated with normalized speech rates. Nevertheless, mean ratings of speech naturalness improved markedly in the device compared to the control condition and, at 3.3 and 3.2 for reading and monologue, respectively, were only slightly outside the normal range. These results show that SpeechEasy produced improved speech outcomes in an assessment setting. However, findings raise the issue of a possible contribution of slowed speech rate to the stuttering reduction effect, especially given participants' instructions to speak chorally with the delayed signal as part of the active listening instructions of the device protocol. Study of device effects in situations of daily living over the long term is necessary to fully explore its treatment potential, especially with respect to long-term stability. Educational objectives: The reader will be able to discuss and evaluate: (1) issues pertinent to evaluating treatment benefits of fluency aids and (2) the effects of SpeechEasy on stuttering frequency, speech rate, and speech naturalness during testing in a dispensing setting for a relatively large sample of adults who stutter.     

Prenatal sex hormones and human aggression: A review,and new data on progestogen effects

We review data on aggression from psychological studies of offspring from two categories of abnormal prenatal sex hormone conditions: 1) endocrine disorders, and 2) hormone treatment during pregnancy. Both sources yield trends and some significant findings that are in line with the animal research based expectations of a positive androgen effect on the development of aggressive behavior. However, the available studies have many methodological weaknesses, and the results are not strong and open to interpretations by factors other than prenatal hormones. Potential modes of prenatal sex hormone effects are also discussed. In the second part, we present data on 13 boys and 15 girls who had been exposed to medroxyprogesterone acetate (MPA) in utero and on 28 closely pair-matched controls. The double-blind follow-up examination at age 9 to 14 years included questionnaires, half-structured interviews with mother and child separately, and a battery of psychological tests. Interviews were tape-recorded and rated by two independent raters. The results show weak but consistent differences, with the MPA-exposed subjects being lower in self- or mother-reported aggression than the controls. The results cannot be accounted for by differences in aggression-related rearing styles. However, the influence of pregnancy pathology cannot be totally excluded. We conclude that the available data are compatible with the hypothesis that prenatal sex hormones influence the development of human aggressive behavior. More sophisticated research studies are needed, however, to demonstrate hormonal effects and their mechanism of action in a reliable and valid fashion.     

Relationships of work stressors with aggression,withdrawal, theft and substance use: An exploratory study

Based on findings from the domain of organizational frustration, the conceptual similarity between stress and frustration, and the functional similarity between frustrated events and work stressors, the relationships of behaviours (aggression, withdrawal, theft and substance use) with work stressors and affective reactions were investigated. Relations between reported stressors and behaviours were strongest for the more directly aggressive actions (sabotage, interpersonal aggression, and hostility and complaints), and for intention to quit. Relations with theft and absence were modest. None of the stressors correlated with reported substance use at work. Among the relations between affective reactions and the reported behaviours, anger and job satisfaction correlated with all behaviours except substance use at work. Hierarchical regression results further showed that the observed associations between stressors and behaviours were not attributed to affective variables for most cases.     

Effects of type and dose of alcohol on human physical aggression.

Forty male undergraduates over 21 years of age were provoked following their ingestion of either 1.5 ounces (.045 1) or .5 ounces (.015 1) of 100 proof bourbon or vodka per 40 (18 kg) of body weight. The expression of physical aggression was related to the quantity of alcohol ingested. The high dose of alcohol appeared to instigate and the low dose of alcohol appeared to inhibit aggressive responding. This effect was most pronounced in the vodka conditions. Interpersonal judgments were also influenced by the type and dose of alcohol consumed.     

The effects of alcohol and delta-9-tetrahydrocannabinol on human physical aggression

Forty male undergraduates were provoked following their ingestion of high or low doses of either alcohol or delta-9-tetrahydrocannabinol (THC). The expression of physical aggression was related to the quantity of alcohol ingested. The high dose of alcohol instigated more intense aggression than the low dose. The high dose of THC, on the other hand, did not increase aggressive behavior. In fact, it tended to produce a weak suppression effect.