Differential facial resemblance of young children to their parents: who do children look like more?

In humans, paternal investment is highly variable and is modulated by paternity uncertainty. Facial phenotypic similarity between a father and a child is one possible paternity indicator. However, whether such paternal-biased traits are expressed in children is unclear, as previous empirical results are contradictory. Therefore, we quantified the facial resemblance between a child and each of his or her parents, from birth to 6 years old. Resemblance was assessed from pictures of the face by nonrelated judges. We found that, at all ages, children resemble both their parents more than would be expected by chance, although there is a differential resemblance toward one or the other parent depending on the age and sex of the child. For newborns, boys and girls resemble their mothers more, this differential resemblance persisting through time for girls. For boys, an inversion occurs and they resemble their fathers more between 2 and 3 years of age. The resemblance ascribed by the parents shows that, at birth, mothers ascribe a resemblance to the father, as previously found, although assessment by external judges revealed the opposite. These results suggest that facial appearance is a cue for kin recognition between a father and a child. Patterns of differential resemblance are discussed within the context of evolutionary theories on parental investment.     

Reproductive patterns and thalassaemia major

This study investigated the effect of the diagnosis of transfusion-dependent homozygous beta-thalassemia on subsequent parental reproductive patterns in 44 families in New South Wales. The results indicate a shift over time from parental risk-taking (either consciously or in ignorance of the implications of the diagnosis) to premature curtailment of reproduction to the likelihood of attaining birth expectations through antenatal diagnosis. 67% of families with both of their 1st 2 children affected by thalassemia major had additional children, compared with 38% of those where the 1st child was affected and the 2nd child was unaffected and 37% of families where the 1st child was unaffected and the 2nd child was affected. Overall, 48% of mothers of children with thalassemia major had as many children as they had expected at the time of marriage, 13% had more, and 39% had fewer children. The mothers of older children were less likely to have had the planned number of births than those of children born more recently. The value of antenatal diagnosis to couples at risk of thalassemia appears to have been to enable them to meet or almost meet their birth expectations.     

Confidence of paternity,divorce, and investment in children by Albuquerque men

Using a sample of men living in Albuquerque, NM, we examined the relationship between paternity confidence and men's investment in children. In humans, men may reduce their investment in a child in two ways: indirectly, by ending their relationship with the child's mother and ceasing to cohabit with the child (e.g., divorce), and directly, by allocating less time and fewer resources to the child. In this article, we tested two hypotheses regarding the effect of paternity confidence on investment in children: (1) men will be more likely to divorce women if they suspect or are sure that they are not the father of their wife's child, and (2) controlling for divorce, men will reduce direct investments in low paternity confidence children relative to high paternity confidence children. The first hypothesis was supported by the data. The second hypothesis was supported for two out of three measures of paternal investment we examined; low paternity confidence reduces the time men spend with a child in a group with other children or adults, and it reduces extensive involvement with the child's educational progress; there was no effect of paternity confidence on the amount of time men spend with children in one-on-one interactions. We also examined the effects of unstated paternity confidence (e.g., when men decline to answer the question) on divorce and paternal investment. Overall, the results suggested that paternity confidence plays an important role in shaping men's relationships with women and with their putative genetic children.     

Be Happy Not Sad for Your Youth: The Effect of Emotional Expression on Age Perception

Perceived age is a psychosocial factor that can influence both with whom and how we choose to interact socially. Though intuition tells us that a smile makes us look younger, surprisingly little empirical evidence exists to explain how age-irrelevant emotional expressions bias the subjective decision threshold for age. We examined the role that emotional expression plays in the process of judging one’s age from a face. College-aged participants were asked to sort the emotional and neutral expressions of male facial stimuli that had been morphed across eight age levels into categories of either “young” or “old.” Our results indicated that faces at the lower age levels were more likely to be categorized as old when they showed a sad facial expression compared to neutral expressions. Mirroring that, happy faces were more often judged as young at higher age levels than neutral faces. Our findings suggest that emotion interacts with age perception such that happy expression increases the threshold for an old decision, while sad expression decreases the threshold for an old decision in a young adult sample.     

An intervention study to increase knowledge and use of folic acid among relatives in neural tube defect-affected families in Washington, D.C

BACKGROUND: Little is known about the level of knowledge and use of folic acid among near relatives in U.S. families of a child with spina bifida. We hypothesized that relatives would be more knowledgeable than the general population and more likely to take folic acid. Further, we hypothesized that relatives would be more motivated by an intervention to increase their use of folic acid. METHODS: We conducted an intervention study among females in families attending a hospital spina bifida clinic in Washington, DC. RESULTS: The 231 subjects consisted of the affected individuals, mothers, sisters, and aunts. The average age was 34 years. At baseline, most (87.4%) reported that they had heard of folic acid; 37.6% were currently taking multivitamins with folic acid and 6.9% were taking folic acid tablets. The intervention significantly increased both knowledge (to 99%) and intake of folic acid from 41.9 to 48.5%. Folic acid intake increased significantly among African-American women and women with less education, women who were older, married, with children, and nonsmokers. CONCLUSIONS: This intervention was successful in increasing folic acid intake among female relatives in spina bifida-affected families. By the end of the study, almost all women had heard of folic acid and folic acid use had increased by 16%. Among these women at higher than expected risk for having an affected child, this rate of intake, while more than the general population, still falls short of optimum. Fortification of food with folic acid may be the only way to ensure increased folic acid intake.     

Social Effects of Genetic Counselling

In a follow-up study of 104 subjects referred for genetic counselling between 1965 and 1969 all were at risk of having children with a variety of serious genetic disorders. Most subjects were in social classes III and IV, were married, in their late 20s, and already had an affected child. Sixty-three per cent. were referred by hospital consultants, 27% by their general practitioners, and 10% were self-referrals. All of those counselled appeared to have appreciated the genetic implications, although four overestimated the risks and 11 underestimated the risks.Of those at high risk (greater than 1 in 10) of having an affected child 10 out of 55 couples “planned” further pregnancies despite the risks. In two this was because they had been unable to adopt a child, in four because they had no living children and the disorders in question usually resulted in stillbirth or death in infancy so that the “burden” of an affected child would be of relatively short duration, and one mother had had antenatal diagnosis and selective abortion. Most of the couples in the low-risk group (less than 1 in 20) were reassured and planned further pregnancies.     

Facial resemblance of Japanese children to their parents

Facial resemblance between parents and their children could be an indicator of genetic relationship, and selective pressure could bias the resemblance of appearance. We assessed the degree of resemblance of 38 Japanese children (3–6 years old) to each of their parents using photographs. We asked nonrelatives to assess which of the parents each child resembled, manipulating indications of the sex of the children. Variance in the degree of resemblance between the children and their fathers was very large. Although the basic facial appearance of each parent can be reflected in each child with 50% probability, the children did not equally show the facial characteristics of each parent at the individual level. The indication of sex had no significant effect on the assessment of resemblance. On the other hand, a questionnaire given to the assessors revealed that, as children, they tended to be said to resemble the opposite-sex parent. This result indicates that alleged resemblance does not reflect an actual condition but rather might have cultural meaning. Electronic Publication     

Trustworthy but not lust-worthy: context-specific effects of facial resemblance

If humans are sensitive to the costs and benefits of favouring kin in different circumstances, a strong prediction is that cues of relatedness will have a positive effect on prosocial feelings, but a negative effect on sexual attraction. Indeed, positive effects of facial resemblance (a potential cue of kinship) have been demonstrated in prosocial contexts. Alternatively, such effects may be owing to a general preference for familiar stimuli. Here, I show that subtly manipulated images of other-sex faces were judged as more trustworthy by the participants they were made to resemble than by control participants. In contrast, the effects of resemblance on attractiveness were significantly lower. In the context of a long-term relationship, where both prosocial regard and sexual appeal are important criteria, facial resemblance had no effect. In the context of a short-term relationship, where sexual appeal is the dominant criterion, facial resemblance decreased attractiveness. The results provide evidence against explanations implicating a general preference for familiar-looking stimuli and suggest instead that facial resemblance is a kinship cue to which humans modulate responses in a context-sensitive manner.     

The Influence of a Working Memory Task on Affective Perception of Facial Expressions

In a dual-task paradigm, participants performed a spatial location working memory task and a forced two-choice perceptual decision task (neutral vs. fearful) with gradually morphed emotional faces (neutral ∼ fearful). Task-irrelevant word distractors (negative, neutral, and control) were experimentally manipulated during spatial working memory encoding. We hypothesized that, if affective perception is influenced by concurrent cognitive load using a working memory task, task-irrelevant emotional distractors would bias subsequent perceptual decision-making on ambiguous facial expression. We found that when either neutral or negative emotional words were presented as task-irrelevant working-memory distractors, participants more frequently reported fearful face perception - but only at the higher emotional intensity levels of morphed faces. Also, the affective perception bias due to negative emotional distractors correlated with a decrease in working memory performance. Taken together, our findings suggest that concurrent working memory load by task-irrelevant distractors has an impact on affective perception of facial expressions.     

The influence of social comparison on visual representation of one's face

Can the effects of social comparison extend beyond explicit evaluation to visual self-representation--a perceptual stimulus that is objectively verifiable, unambiguous, and frequently updated? We morphed images of participants' faces with attractive and unattractive references. With access to a mirror, participants selected the morphed image they perceived as depicting their face. Participants who engaged in upward comparison with relevant attractive targets selected a less attractive morph compared to participants exposed to control images (Study 1). After downward comparison with relevant unattractive targets compared to control images, participants selected a more attractive morph (Study 2). Biased representations were not the products of cognitive accessibility of beauty constructs; comparisons did not influence representations of strangers' faces (Study 3). We discuss implications for vision, social comparison, and body image.     

Shyness in Early Infancy: Approach-Avoidance Conflicts in Temperament and Hypersensitivity to Eyes during Initial Gazes to Faces

‘Infant shyness’, in which infants react shyly to adult strangers, presents during the third quarter of the first year. Researchers claim that shy children over the age of three years are experiencing approach-avoidance conflicts. Counter-intuitively, shy children do not avoid the eyes when scanning faces; rather, they spend more time looking at the eye region than non-shy children do. It is currently unknown whether young infants show this conflicted shyness and its corresponding characteristic pattern of face scanning. Here, using infant behavioral questionnaires and an eye-tracking system, we found that highly shy infants had high scores for both approach and fear temperaments (i.e., approach-avoidance conflict) and that they showed longer dwell times in the eye regions than less shy infants during their initial fixations to facial stimuli. This initial hypersensitivity to the eyes was independent of whether the viewed faces were of their mothers or strangers. Moreover, highly shy infants preferred strangers with an averted gaze and face to strangers with a directed gaze and face. This initial scanning of the eye region and the overall preference for averted gaze faces were not explained solely by the infants’ age or temperament (i.e., approach or fear). We suggest that infant shyness involves a conflict in temperament between the desire to approach and the fear of strangers, and this conflict is the psychological mechanism underlying infants’ characteristic behavior in face scanning.     

The development of face processing skills.

An early orientation to faces is followed by a gradual development of face processing skills. During the course of maturation, children acquire the ability to learn new faces and to deal with facial transformations. Some skills are achieved more quickly than others. Moreover, encoding ability in young children is somewhat different from that shown by older children. The younger groups fail to take advantage of increased inspection time and stimulus characteristics such as facial distinctiveness. They are also more likely to be confused by alterations in background context. Although with familiar faces they reveal very similar identity priming effects to older children and adults, younger children display a relative inefficiency in categorizing faces as being that of a target unless it is noticeably dissimilar. Young children are more likely than older people to prefer positive caricatures of certain faces, which is not consistent with the view that caricature effects are simple reflections of a general expertise with faces.     

Is Beauty in the Face of the Beholder?

Opposing forces influence assortative mating so that one seeks a similar mate while at the same time avoiding inbreeding with close relatives. Thus, mate choice may be a balancing of phenotypic similarity and dissimilarity between partners. In the present study, we assessed the role of resemblance to Self’s facial traits in judgments of physical attractiveness. Participants chose the most attractive face image of their romantic partner among several variants, where the faces were morphed so as to include only 22% of another face. Participants distinctly preferred a “Self-based morph” (i.e., their partner’s face with a small amount of Self’s face blended into it) to other morphed images. The Self-based morph was also preferred to the morph of their partner’s face blended with the partner’s same-sex “prototype”, although the latter face was (“objectively”) judged more attractive by other individuals. When ranking morphs differing in level of amalgamation (i.e., 11% vs. 22% vs. 33%) of another face, the 22% was chosen consistently as the preferred morph and, in particular, when Self was blended in the partner’s face. A forced-choice signal-detection paradigm showed that the effect of self-resemblance operated at an unconscious level, since the same participants were unable to detect the presence of their own faces in the above morphs. We concluded that individuals, if given the opportunity, seek to promote “positive assortment” for Self’s phenotype, especially when the level of similarity approaches an optimal point that is similar to Self without causing a conscious acknowledgment of the similarity.     

Detection of Propensity for Aggression based on Facial Structure Irrespective of Face Race

The human face provides a wealth of information pertaining to the internal state and life-stage history of an individual. Facial width-to-height ratio is a size-independent sexually dimorphic trait, and estimates of aggression made by untrained adults judging own-race faces were positively associated with both facial width-to-height ratio and actual aggressive behavior. Given the significant adaptive value of accurately detecting aggressiveness based on facial appearance, we hypothesized that aggression estimates made by adults and 8-year-olds would be highly correlated with male facial width-to-height ratio even for a face category with which they had minimal experience-other-race faces. For each of the four race and age groups, estimates of aggression were positively correlated with facial width-to-height ratio irrespective of rating own-or other-race faces. Overall, the correlations between facial width-to-height ratio and ratings of aggression were stronger for adults than for children. Sensitivity to facial width-to-height ratio appears to be part of an evolved mechanism designed to detect threats in the external environment. This mechanism is likely broadly tuned and functions independently of experience.     

Who teaches children to forage? Exploring the primacy of child-to-child teaching among Hadza and BaYaka Hunter-Gatherers of Tanzania and Congo

Teaching is cross-culturally widespread but few studies have considered children as teachers as well as learners. This is surprising, since forager children spend much of their time playing and foraging in child-only groups, and thus, have access to many potential child teachers. Using the Social Relations Model, we examined the prevalence of child-to-child teaching using focal follow data from 35 Hadza and 38 BaYaka 3- to 18-year-olds. We investigated the effect of age, sex and kinship on the teaching of subsistence skills. We found that child-to-child teaching was more frequent than adult-child teaching. Additionally, children taught more with age, teaching was more likely to occur within same-sex versus opposite-sex dyads, and close kin were more likely to teach than non-kin. The Hadza and BaYaka also showed distinct learning patterns; teaching was more likely to occur between sibling dyads among the Hadza than among the BaYaka, and a multistage learning model where younger children learn from peers, and older children from adults, was evident for the BaYaka, but not for the Hadza. We attribute these differences to subsistence and settlement patterns. These findings highlight the role of children in the intergenerational transmission of subsistence skills.     

Sex differences in ability to recognize family resemblance

In order to test the different expectations of evolutionary psychologists and “folk” psychologists about whether men or women are better at judging family resemblance, we created a test consisting of pairs of photographs, some of a parent and that parent's child, and some of an unrelated parent and child. Two hundred subjects judged the relatedness of 24 pairs of photos. The results show women and men to be equal in ability to judge family resemblance (mean number correct 14.99 versus 14.53, F = 1.7, p = 0.19). Both sexes were better able to judge resemblance for mothers than fathers (F = 11.25, p < 0.0001), and men and women were better at judging relatedness for children of their own sex (F = 3.99, p < 0.05). Ability to judge family resemblance was not related to the rater's age, marital status, number of siblings, number of children, or years of education. On a test of ability to recall faces, women were superior (F = 4.14, p < 0.043). These findings are considered in relationship to previous research and to the predictions of evolutionary and folk psychology.     

The paternal-age effect in Apert syndrome is due,in part,to the increased frequency of mutations in sperm

A paternal-age effect and the exclusive paternal origin of mutations have been reported in Apert syndrome (AS). As the incidence of sporadic AS births increases exponentially with paternal age, we hypothesized that the frequency of AS mutations in sperm would also increase. To determine the frequency of two common FGFR2 mutations in AS, we developed allele-specific peptide nucleic acid-PCR assays. Analyzing sperm DNA from 148 men, age 21-80 years, we showed that the number of sperm with mutations increased in the oldest age groups among men who did not have a child with AS. These older men were also more likely to have both mutations in their sperm. However, this age-related increase in mutation frequency was not sufficient to explain the AS-birth frequency. In contrast, the mutation frequency observed in men who were younger and had children with AS was significantly greater. In addition, our data suggest selection for sperm with specific mutations. Therefore, contributing factors to the paternal-age effect may include selection and a higher number of mutant sperm in a subset of men ascertained because they had a child with AS. No age-related increase in the frequency of these mutations was observed in leukocytes. Selection and/or quality-control mechanisms, including DNA repair and apoptosis, may contribute to the cell-type differences in mutation frequency.     

Familial aggregation of blood pressure in 558 adopted children.

Blood pressure was measured in each member of 398 French-Canadian families with at least one adopted child of the same ethnic origin. Measurements were made at home by a nurse, usually with the subject seated. One comparison per family between parents and randomly chosen index children was made, using age- and sex-adjusted scores. The correlation in blood pressure scores between parents and natural children was highly significant (P less than 0.001), at 10.2% for systolic and 13.7% for diastolic in 140 homes with at least one natural child, but the correlation between parents and adopted children was nonsignificant, at 0.81% and 1.0%, in 398 homes with at least one adopted child. The correlation between pairs of natural children was significant (P less than 0.05), at 7.84% for systolic and 8.41% for diastolic, in 80 homes with more than one natural child but nonsignificant, at 0.49% and 1.69%, respectively, for pairs of adopted children in 138 families with more than one adopted child. It is concluded that heredity explains most of the familial resemblance of blood pressure in children.     

Patterns of fractures in accidental and non-accidental injury in children: a comparative study.

The incidence and pattern of fractures in children who had been abused were compared with those of fractures sustained by children of similar ages in whom abuse had been excluded. From 1976 to 1982 there were 35 children with fractures resulting from child abuse, and all were aged under 5. Of the 826 children in the control group, seen from January to June 1981, 85% were aged over 5. Abused children were much more likely to have multiple fractures (p less than 0.001) and bruising of the head and neck (p less than 0.001). Fractures of the ribs were common in children who had been abused, and their presence, in the absence of major chest trauma, strongly suggested that abuse was occurring. Injuries to the long bones were invariably spiral or oblique fractures or subperiosteal new bone formation--both "gripping or twisting" injuries. Spiral fracture of the humeral shaft was significantly more common (p less than 0.001) in the group of abused children. Classic metaphyseal chip fractures were uncommon. One child in eight aged under 18 months who sustains a fracture may be a victim of child abuse.     

Categorical Perception of Fear and Anger Expressions in Whole,Masked and Composite Faces

Human observers are remarkably proficient at recognizing expressions of emotions and at readily grouping them into distinct categories. When morphing one facial expression into another, the linear changes in low-level features are insufficient to describe the changes in perception, which instead follow an s-shaped function. Important questions are, whether there are single diagnostic regions in the face that drive categorical perception for certain parings of emotion expressions, and how information in those regions interacts when presented together. We report results from two experiments with morphed fear-anger expressions, where (a) half of the face was masked or (b) composite faces made up of different expressions were presented. When isolated upper and lower halves of faces were shown, the eyes were found to be almost as diagnostic as the whole face, with the response function showing a steep category boundary. In contrast, the mouth allowed for a substantially lesser amount of accuracy and responses followed a much flatter psychometric function. When a composite face consisting of mismatched upper and lower halves was used and observers were instructed to exclusively judge either the expression of mouth or eyes, the to-be-ignored part always influenced perception of the target region. In line with experiment 1, the eye region exerted a much stronger influence on mouth judgements than vice versa. Again, categorical perception was significantly more pronounced for upper halves of faces. The present study shows that identification of fear and anger in morphed faces relies heavily on information from the upper half of the face, most likely the eye region. Categorical perception is possible when only the upper face half is present, but compromised when only the lower part is shown. Moreover, observers tend to integrate all available features of a face, even when trying to focus on only one part.