Gender and Birth Order as Determinants of Parental Behaviour

International Journal of BehavioralDevelopment http://jbd.sagepub.com Gender and birth order as determinants of parental behaviour Heidi Keller and Ulrike Zach International Journal of Behavioral Development 2002; 26; 177 DOI: 10.1080/01650250042000663 The online version of this article can be found at: http://jbd.sagepub.com/cgi/content/abstract/26/2/177 Published by: http://www.sagepublications.com On behalf of: International Society for the Study of Behavioral Development Additional services and information for International Journal of Behavioral Development can be found at: Email Alerts: http://jbd.sagepub.com/cgi/alerts Subscriptions: http://jbd.sagepub.com/subscriptions Reprints: http://www.sagepub.com/journalsReprints.nav Permissions: http://www.sagepub.com/journalsPermissions.nav Citations (this article cites 25 articles hosted on the SAGE Journals Online and HighWire Press platforms): http://jbd.sagepub.com/cgi/content/refs/26/2/177 Downloaded from http://jbd.sagepub.com by stefan boncu on November 28, 2007 © 2002 International Society for the Study of Behavioral Development. All rights reserved. Not for commercial use or unauthorized distribution. the residence pattern and the household type (cf. & Barnett. Dunn & Plomin. mainly school-aged children and adolescents have been assessed.uni-osnabrueck. and father’s face-to-face behaviour when the mother is also present. 1972).and laterborn boys and girls on parental treatment. 1991). for example. University of Osnabru¨ck. With respect to birth order. LeVine. a controversial picture emerges.html DOI: 10. 1985. Barnett. stimulation (cf. but as the simultaneous presence of microenvironments or developmental niches (Keller. Dunn. for example. Mothers interact more intensively with their daughters. Unexpectedly. With respect to gender differences. With respect to children’s gender. Riesmann.1080/01650250042000663 Gender and birth order as determinants of parental behaviour Heidi Keller and Ulrike Zach University of Osnabru¨ck. parental in uences have to be differentiated into fathers’ and mothers’ individual and joint contributions to children’s development (Lamb.tandf. 1997). The data reveal a sound birth rank effect. the interaction between gender and birth order as determinants of differential parental treatment has not been accorded much attention in the literature. the socioeconomic framework. 1971. & Plomin. 1963). e-mail: Hkeller@luce. 1994). All rights reserved.sagepub. 1982. Thoman. the subsistence activities. for English mothers. 1971. Department of Psychology. Vo¨lker. for USAmerican mothers). for US-American mothers). Developmental studies have documented that the family can no longer be conceived of as one homogeneous system. parental treatment has been related to the development of children’s personality. 1977. and talking (Thoman. for English mothers). when. Dunn & Kendrick. Sulloway. birth order seems to produce a robust effect on differential parental treatment towards infants. for USAmerican mothers). Crouter & McHale. for USAmerican mothers). We thank Mirian Abrams and Marion Guemmer for data collection and data analysis. 1991. This developmental pattern is interpreted as part of gender socialisation throughout childhood. Turner. indicating that Ž rstborns are preferred over laterborns in several respects: presence of mothers.g.and laterborns are contrasted. the oldest children are accorded higher status in traditional societies (Daly & Wilson. Special attention is awarded to Ž rstborns in terms of the number of feeding intervals (Thoman. 49069 Osnabru¨ck. 1997). Downloaded from http://jbd. and maternal and paternal facial exchange with the baby were assessed during videotaped observation sessions equivalent to a full day.uk/journals/pp/01650254. play (e. & Marner. & Nettles. 1980. The social context of fathers’ and mothers’ joint presence reveals the only interaction effect between gender and birth order with the preference of Ž rstborn boys. 1992.. Moss. Presence of parents. Munck. Thoman et al. & Olson. Among the intricate network of structural parameters in which the family system is nested. for Danish mothers. This study was supported with a grant of the VW-Foundation to the Ž rst author. 177–184 # 2002 The International Society for the Study of Behavioural Development http://www. which create a different context for each child within the same family (cf. Hetherington. Seminarstraße 20. Moreover. interaction time (Dunn. cultural practices re ect the special value of the roles of Ž rstborns. 26 (2). 1990. Seifer. Reiss. Plomin & De Fries. The Ž ndings are related to previous research results as well as evolutionary considerations about parental investment. & Chasiotis... Plomin.psycho. 1985. 1989. Cappenberg. 2000. whereas fathers’ engagement in parenting is predominantly directed at their sons (e. Keller. consistency and indulgence (Dunn. Respective differences in parental treatment substantiate the nonshared rearing environment for children of different gender and age in the same family.g. Lamb. Mirdal. Jacobs and Moss Correspondence should be addressed to Heidi Keller.International Journal of Behavioral Development 2002. Not for commercial use or unauthorized distribution. & Jankowski. 1970. Stocker. 1994). Germany This study analyses the effect of gender and birth order of Ž fty-eight 3-month-old Ž rst. Sameroff. newer studies have mainly come to the conclusion that the gender of the child is not a powerful variable for explaining differences in parental behaviours (e. 1992).de. especially when Ž rst. 1995. for English mothers). Rubenstein. 2001). 2007 © 2002 International Society for the Study of Behavioral Development. 1997. 1985.com by stefan boncu on November 28. the individual experiences of children in a family are basically in uenced by gender and birth order. Leiderman. We are indebted to Baerbel Buch and Monika Biener for the coordination of the empirical assessment. . also in terms of normal and deviant developmental trajectories. However. It has been demonstrated that mothers’ differential treatment towards siblings is an important predictor of variations in adjustment (Dunn & Plomin.g.co. Moreover. Anagnostopolou & Elias. maternal primary care. 1967. Restricting the focus to infancy studies. psychological studies have repeatedly demonstrated that there is a gender-speciŽ c involvement between parents and their children. Whiting. Germany. 1972. 1999. & Plomin. Lohaus. 1988. Also. mothers prefer their daughters in terms of presence and primary care. Leiderman. 2000). Fathers prefer their sons in terms of presence. Whereas some older studies emphasise differences (Bakeman & Brown. Plomin. The shared family environment explains only about 5% of variance in individual personality traits of siblings (Pike & Plomin. Pederson. Yovsi. presence of fathers. Accordingly. & Leiderman. Yarrow. fathers prefer their daughters in terms of face-to-face exchange. Cronk. because it constitutes the framework for special activities and communicates general availability (e. and general responsiveness than with their Ž rstborn daughters (Parke. This hypothesis has come to be used as being synonymous with any gender-biased parental investment before or after birth since then (Hrdy. the reproductive value of offspring is constituted especially through gender and birth order which consequently can be regarded as pervasive criteria for investment decisions. An evolutionary consideration of gender differences is mainly based in the hypothesis introduced by Trivers and Willard (1973). Although there appears to be support for the assumption that human parents invest differentially into sons and daughters after birth. Thus the interaction of these variables becomes crucial for this age range. 1987). offers with the model of differential parental investment a conceptual framework to explain why parents might behave differently towards siblings of different gender. 1991). there is mixed evidence for the effect of gender on differential parental treatment during infancy. 1998). Wolof in West Africa. for example. New England states before the Declaration of Independence (Judge & Hrdy. Psychological studies and studies within the framework of evolutionary theory have supported strong evidence for birth order effects. Investment decisions result from monitoring costs and beneŽ ts with respect to the parents’ reproductive Ž tness and are mainly implicit and nonconscious. Parental investment is deŽ ned as any effort by an individual parent that increases the probability of surviving—and therefore the reproductive success—of a particular offspring. as well as the respective gender. for example. we would like to explore gender and birth order effects in regard to different caregiving contexts. 2007 © 2002 International Society for the Study of Behavioral Development. Hewlett. that ‘‘. The rationale for this hypothesis is based in the assumption of a higher variability of the reproduction potential of males as compared to females as a consequence of sexual selection and reproduction in humans. thus. different systems of parenting must also be considered (see Keller. 1961).. but also on the birth position of the child. their results demonstrated that a gender-biased maternal treatment became apparent mainly with secondborn infants with a preference for boys. 1991).’’ (p. . time spent with the child (Boone. a parent might invest more into sons if the socioeconomic environment remains intergenerationally stable and predictable. As has been argued earlier. 18th-century northern German villages (Voland. Falade. sibling competition for parental love is regarded as an important driving force in human evolution. 1990).sagepub. clothes. on the other hand. such as frequency and length of nursing periods (Cronk. natural selection favors deviations from a 50:50 gender ratio at conception . thus meeting basic needs. Hrdy. 1987. With the present study. for a summary see Cronk. under certain well deŽ ned conditions. fathers were more involved with Ž rstborn sons in terms of vocalisation. From an evolutionary perspective. 1987). In particular. & West. In particular. We therefore restrict our analysis of differential parenting to an af uent middle class environment. Voland.com by stefan boncu on November 28. Not for commercial use or unauthorized distribution. . as a Ž rst mode of relationship quality has been established which seems to have developmental consequences (Chasiotis et al. Their results indicated that mothers spent less time in social affectionate and caretaking activities with their secondborn children as compared to their Ž rstborns. All rights reserved.g. or frequency of parent-child interaction (Betzig & Turke. children’s characteristics that mark their developmental niche in a family comprise. Accordingly.178 KELLER AND ZACK / GENDER AND BIRTH ORDER (1976). balance the parental condition in a given context with the reproductive value of the respective child. O’Leary. 1991. Keller & Zach. & Crawford. However. 1988). As well as health and vitality. 1991. This preference of sons over daughters under af uent conditions has been documented in. In addition to parameters. In environments with scarce and unpredictable resources. Because it is difŽ cult to identify otherwise similar families in different socioeconomic circumstances that could represent different resource situations in sociobiological terms in Western European urban areas. 1987). especially parenting systems and caregiving persons. Zach. expenditure of food. 1986. Firstborn males and females did not receive differential maternal treatment. 1972. 1987. . Sociobiological studies have deŽ ned parental investment mainly as mere length of time of presence. a parent ought to invest primarily into daughters as their reproductive success is less variable than that of their sons (cf. It can therefore be assumed that the gender differences in parental allocation of investment might depend not only on the socioeconomic circumstances. . 1971. Lebanese culture (Prothro.. Hrdy. As well as investment of time. however. Keller & Gauda. Mainly cross-cultural studies have indicated that not only mothers’ presence. Mokogodo in Kenya. . Investment decisions. we do not intend to test evolutionary assumptions directly by contrasting parental behaviour across different socioeconomic contexts. Hrdy. 1999). 1998. 1993. we explore the effect of gender and birth order as well as their interaction as determinants of differential parental behaviour towards their young infants. 90). 1975). it has been observed in different societies that girls from low-income families or single parent households are nursed longer than boys (US-America. With our home observation study. and (b) a dyadic face-to-face system that constitutes the most prominent social parenting system in Western industrialised societies. these psychological studies have focused on the description of differences and their developmental consequences for children’s behavioural and mental achievements. 2000): (a) a primary care system that provides nursing and feeding. 1974). the age of about three months qualiŽ es for the assessment of differential parenting. 1989. decreasing at the same time the degree of investing in other descendants (Trivers. On the other hand. 1987). Differences in parental treatment have to be speciŽ ed with respect to different behavioural systems. and medical care (Das Gupta. have assessed 41 maternal and infant behaviours with 32 middle class mothers and their 3-monthold Ž rstborn and secondborn children during several hours of observation. 1986) have been assessed as expressions of parental investment in small children. which also might account for differences in personality formation (Sulloway. Kish. and in present Canadian British Columbia (Smith. a number of studies fails to conŽ rm the predictions of the Trivers and Willard hypothesis (cf. but also the presence of other potential caregivers have to be assessed. Evolutionary theory. With this study. Do middle class mothers and fathers treat their 3month-old boys differently than their same aged daughters? Downloaded from http://jbd. 2000). thus ascertaining the reproductive success of the male offspring. 2000). we addressed the following questions: 1. Sieff. Birth position reveals information about the parity of the parent as well as the sibship system of the child (Sulloway. Gaulin & Robbins. touching. the individual birth position. Generally. 1997. 1987). 1998). Table 1 Sample characteristics Firstborn Sample size (n ˆ 58) Age of mothers at Ž rst birth Age of fathers at Ž rst birth Duration of partnership at birth of the Ž rst child a 17 laterborn boys were secondborn. a second home visit was scheduled to establish informed consent about participation in the study. The mothers did not report alteration of their daily routines.m.61) 31. n ˆ 20. The observation period ideally covered the routine day from 8 a. When the infants were between 11 and 13 weeks old. the observer visited the family for the last time and asked them to evaluate. 26 (2). and face-to-face interaction. in retrospect. 2. The majority of laterborn children (n ˆ 23) were secondborn (17 boys).14) 2. ANOVAS. Parents were informed that the purpose of the study was the assessment of the general daily experiences of young infants in Germany.sagepub. The families were asked to continue with their normal daily routine without paying attention to the observer as far as possible.70 (4.5% of fathers had completed high school. the observation time was adapted accordingly (e. The differences in the parents’ age at the observation time are part of the parental condition that might produce differential treatment of infants.18) 3. we included not just secondborn children into our sample (Sulloway. 2 (gender) £ 2 (birth position). 1994). We would like to further explore the effect of the interaction between gender and birth order for mothers’ and fathers’ presence. They then completed the Infant Behavior Questionnaire (IBQ. Procedure The families were Ž rst contacted during the last trimester of the women’s pregnancy. primary care. 3. indicated no signiŽ cant differences regarding the mean ages of mothers and fathers and the duration of partnership at the time of Ž rst birth. According to fathers’ education (all families were middle class).. we expect that: – middle class mothers and fathers invest more into Ž rstborns than into laterborns in terms of person’s presence. to 7 p. .m. One week after completion of the observation blocks. spontaneous.88 (2. Thus the socioeconomic parental conditions of the four subsamples were comparable.76) 3. all families were complete.5 (2.78) 13 28 (4. but four thirdborn children (2 girls) also participated. From the psychological literature. Scho¨lmerich. short-term observations of interactional exchanges could imply instructions or at least directions of what is being observed.g.com by stefan boncu on November 28.56 (3.31) 28. from 9 a.91 (4. 2 thirdborn. primary care and face-to-face interaction: From the psychological literature. 76. The family routine was discussed and the observation schedule was planned accordingly. primary care. had known each other for approximately three years when the Ž rst child was born and fathers predominantly worked in higher educated jobs. induced). Weekends were excluded in order to be not too intrusive. 13. the families were visited on Ž ve consecutive days during different times of day for observation periods of two hours each. 1997. to 6 p.5 college and university education. All mothers had normal pregnancies and deliveries (n ˆ 38. Do middle class mothers and fathers treat their Ž rstborn 3-month-old infants differently than their same aged laterborns? From an evolutionary perspective.60 (5) 10 26. If the family had a discrepant time schedule. Ten weeks after delivery.50) 6 laterborn girls were secondborn. All rights reserved.). 177–184 From an evolutionary perspective. From the psychological literature.14 (4. At the time of data collection. it can also be assumed that: – Ž rstborns are preferred over laterborns. mainly from their mothers. 2002. 2000).92 (2. Because we were interested in the differences of parental treatment towards Ž rstborns and laterborns and not in children’s behavioural strategies which might be associated with different functional birth ranks. Furthermore. as brief. Not for commercial use or unauthorized distribution. The demographic information was assessed during this Ž rst home visit. Method Participants The two samples comprised a total of 58 families with 29 Ž rstborn (16 boys) and 29 laterborn (19 boys) 3-month-old infants from a northern German urban area. and face-to-face interaction.m. 2007 © 2002 International Society for the Study of Behavioral Development.4 (2.7) 19 27. The sample was recruited through announcements in the local newspaper and visiting birth preparation and partnership classes offered by hospitals and family counselling services. b Laterborn a Boys Girls Boys Girlsb 16 27.59) 28. parents were in their late twenties. Lamb.91) 4. Referring to the means of the total sample. Sample characteristics and mean ages of mothers and fathers and duration of partnership at Ž rst birth are presented in Table 1.10 (3. it can be assumed that: – same sex infants are preferred over different sex infants from mothers and fathers. & Fricke. Downloaded from http://jbd.31 (3. it can be expected that: – Ž rstborn same sex children are preferred over all other groups. Extended observational periods are necessary to address the questions of this study. we expect that: – middle class mothers and fathers invest more into boys than into girls in terms of person’s presence. 2 thirdborn. Traub. and therefore possibly interfere with naturally occurring interaction modes.m.179 INTERNATIONAL JOURNAL OF BEHAVIORAL DEVELOPMENT. their presence during the observation periods with respect to the in uence of normal routine of the family and the infants’ states and behaviour during that time. whereas longer observation blocks should produce more valid information (Leyendecker.2) 33. unstructured observation periods might yield unreliable measures. as the correlation between both states was high (Keller et al. Results Persons’ presence Mother’s presence. parental primary care. Presence of mother.92) (0.06 3. Three advanced students coded the videotaped observational periods.30 (2.and offsets of presence were coded separately for each person.87) (1.14 3..94) 4. the observer terminated the conversation in a polite manner. ANOVAs. Awake was coded when the infant was awake with open eyes and alert. faceto-face exchange was coded. Table 2 presents the descriptive statistics of infants’ states and the temperamental characteristics as assessed with the different dimensions of the IBQ.23 (0.64 3.84) 3.34 2. The variable was coded separately for each person involved.19) 3.65) (0. fathers’.38) (0. All rights reserved. which corresponds to M ˆ 4. persons present: kappa ˆ . 2 (gender) £ 2 (ordinal position). No signiŽ cant Table 2 Means (and standard deviations) of observational time (hours).55) 56. In order not to lose information (as is the case.99 (15.82) (0. did not yield signiŽ cant differences between the subsamples with respect to observation time and hours awake.91) . The observation time for all subsamples was almost 9 hours with an infant waking time of approximately 5 hours.64) (0.81 (0. 1981) for the target child. Sleep was coded when the infant slept or was about to fall asleep.55 (0.90 (10. The observer took protocol notes of persons’ presence and their caregiving and social activities. cry/fuss: kappa ˆ .05) 47. when the caretaker left the house with the infant.48 4.72. Fuss and cry durations were collapsed. this was coded as ‘‘crying’’.94.53 (14.28 3.10 1.86) (1.79 hours (SD ˆ 1.40 (14. Signs for falling asleep are yawning. Inter-observer agreement between the three coders was computed for three subjects on the basis of two randomly chosen video sequences ranging from 16 to 40 minutes.94 (3. infant awake: kappa ˆ . Breast feeding or bottle feeding was coded as nursing.98.27) 36.sagepub.59) (0. Comparability of the samples.05) 39. We had to ascertain that the variables of interest (presence. On.29 2.3).44 (0. The presence of other people was so infrequent that it was excluded from further analysis.86) 4.70) was established.g.74) (0.13 (10. Not for commercial use or unauthorized distribution.. persons’ presence. When the infant was awake and manifested signs of agitation or upset by moaning.08 3.29) 48. Face-to-face exchange.91 (0.21) 42. infants’ states. Additional 2 (ordinal position) £ 2 (gender) ANOVAs indicated that variations in the maternal perception of infant characteristics were not linked to ordinal position or gender of the infant. relaxed muscle tone.29 4.81) 8. primary care.33 (0.53 3.19 (15.90) (1. face-to-face exchange) were not confounded with actual states of the infant or with maternal perception of temperamental characteristics.53) (0.73) 5.75) (0.37 (16.74) (0.97 (0.48 (14. face-to-face system: kappa ˆ .16 3. eyes closed. and face-to-face exchange were assessed.41) (0. Primary care. 2007 © 2002 International Society for the Study of Behavioral Development. the onsets and offsets of the behavioural categories were recorded in microseconds.21) Reported as percentages of observational time and perceived child characteristics IBQ. Codes were all deŽ ned exclusively. Each nursing event was coded for the respective person who was involved with the baby. If addressed. Measures On the basis of the videotaped observation time.51) 3.54 (3.44) (0. Persons’ presence. It became evident that regardless of ordinal position and gender of their young infant the mothers spent 85% of the infant’s waking hours with the infant.180 KELLER AND ZACK / GENDER AND BIRTH ORDER Rothbart. father. Based on coding units of one second.67) (0.54 4. a good inter-rater agreement (nursing: kappa ˆ . The complete observation blocks were videotaped with the camera focused on the baby. 1996).98 3.12 2. infants’ statesa Firstborn Boys Observation time (hours) Awake Sleeping Crying/fussing Activity level Distress to limitations Distress to new stimuli Smiling and laughter Fear Soothability Duration of orientation a Laterborn Girls Boys Girls 8.70 (0.00) (0. 2 (ordinal position) £ 2 (gender).99) 54. Inter-observer agreement.com by stefan boncu on November 28. Post-hoc analyses of these data enables the assessment of bouts of mothers’.63) (1. in time sampling procedures). and wimpering. e.25 3. ANOVAs. The observer did not initiate interaction with the baby and/or family members.41 3.72) 6.90 3. Infant’s states.02) (0. indicated that infants’ states did not differ with respect to ordinal position and gender.93. and siblings’ presence.83) 8.18 3. and the speciŽ cation of mothers’ and fathers’ time spent alone with the baby as well as parents’ simultaneous presence. Also attempts to nurse were coded regardless of the infant’s actual milk intake.89.84) (0.63) (1. and siblings was deŽ ned as being within viewing and/or hearing distance of the child. Downloaded from http://jbd.31 4. When the target infant and a person were in the physical position to look at each others’ faces.87) 8.18 2. bottle feeding: kappa ˆ .83) (0. 3.03 4.90) (0.90 4.93) (1. whining. The observation blocks and the home visits were conducted by one female observer in order to maximise familiarity and to minimise interference with the family environment.79 4. the state ‘‘fussy’’ was assigned and when the infant cried at least for three seconds with accompanying gestures.82 (3.75) 52. Fathers were present at an average of 23% of the infants’ waking hours.95) 227. but not for the laterborn infants (see Figure 1).005). group differences between the four groups of infants emerged with respect to maternal overall total presence (see Table 3). p < .87)a 56. When controlling for the time the siblings were present in the group of the laterborn infants.20)b 36. computed as a percentage of the time the infants were awake (see Table 3). 54) ˆ 6.60) 64 (69. In a next step.29 (80. the results demonstrate that fathers spent more time with their boys and with their Ž rstborns. p < . Regarding the time the mothers were alone with their young infants a different picture emerged: A 2 (ordinal position) £ 2 (gender) ANOVA yielded a signiŽ cant main effect for ordinal position F(1.86 (22.43) 77 (18. The signiŽ cant interaction effect for ordinal position and gender indicated signiŽ cant gender differences for Ž rstborn infants.66 (18.18 (80. 2007 © 2002 International Society for the Study of Behavioral Development. F(1. F(1. The siblings of the laterborn infants were present during 36% of the infants’ waking hours (M ˆ 1.000. An interaction between ordinal position and gender can be Figure 1. p < .7. indicating that mothers were alone signiŽ cantly longer with their Ž rstborn infants than with their laterborn infants (Ms ˆ 65% vs. a signiŽ cant main effect for gender emerged.85) 33 (22.87)a 107 (86. and they were together longer with boys (M ˆ 23%) than with girls (M ˆ 13%).com by stefan boncu on November 28.05 or lower).69 (28.33 (30.05: Mothers were alone signiŽ cantly longer with a female infant (M ˆ 55%) than with a male infant (M ˆ 37%).41)b 45.59) 78 (35. p < . Thus.51)b 26. 23%). No interaction occurred between ordinal position and gender. 48) ˆ 5.08 (78. 51) ˆ 6.08.46)a 255. Downloaded from http://jbd. Fathers and mothers together with the infant.43) 230.75) Siblings’ presence with the infant Total time of fathers’ presence Time of mothers’ and fathers’ simultaneous presence Maternal primary care 37.08. which corresponds to a mean time of M ˆ 68.69 (16. . With respect to the time both parents were present simultaneously a 2 (ordinal position) £ 2 (gender) ANOVA yielded a signiŽ cant main effect for ordinal position.91) 61 (24. Mothers’ spending less time with their laterborns might be related to the presence of siblings in the group of laterborn infants. A 2 (ordinal position) £ 2 (gender) ANOVA revealed a signiŽ cant main effect for ordinal position of the infants. corresponding time in minutes is added in italics. p < .24 (96.31) 284.47 (81. F(1. Post-hoc Schefe pairwise comparisons speciŽ ed that mothers’ and fathers’ simultaneous presence was highest for Ž rstborn boys (M ˆ 37%) and signiŽ cantly different from all other groups of children (ps < . Also.05.42) 166. 177–184 Table 3 Means (and standard deviations) of the percentages of family members’ presence during infants’ state of alertness and the percentages of maternal primary care during the time being present Firstborn Total time of mothers’ presence Mother alone with the infant Laterborn Boys Girls Boys Girls 85 (33.33 (28.78.04) 15 (8.56) 36 (21.44) 11 (13.15)a 97. this social context was excluded from further data analyses.33)b Notes: Means within a row with different subscripts differ signiŽ cantly (p < . we analysed the total time the fathers spent with the infants and the time fathers spent alone with their young infants. 26 (2).11) 60 (27.28) 82 (37.82) 307. as fathers were present longer with boys (M ˆ 29%) than with girls (M ˆ 16%).000. as well as an interaction effect.54). p < .12. Fathers’ presence. F(1.65 (74.03) 99 (1.37 (54.97)a 168. 2002. The interaction between ordinal position and gender with respect to parents’ presence. There was also a signiŽ cant main effect for gender.sagepub.15)b 22.46) 37 (24. Both parents were present longer with Ž rstborn infants (M ˆ 25%) than with laterborn infants (M ˆ 10%). Taken together.82.05). 51) ˆ 51. no signiŽ cant group differences regarding the time the mothers spent alone with the young infant emerged.69)a 50. SD ˆ 2. All rights reserved.05. M ˆ 15%.05) 11 (13. Not for commercial use or unauthorized distribution. F(1.30)b 27 (31. Fathers spent more time in the presence of Ž rstborn babies (M ˆ 29%) than in the presence of laterborn babies (M ˆ 17%). t(26) ˆ 2.13 (88.05. For illustrative purposes.81.76) 70 (21.21) 11 (8.59.34.30)b 106.47) 21 (21. p < .26 minutes (SD ˆ 21. 54) ˆ 51. p < .73 (93. a signiŽ cant main effect for gender.36) 19 (11. F(1.61)b 50.63 (39. whereas 45 fathers did not. The time siblings were present did not differ signiŽ cantly for male (M ˆ 77%) or for female babies (M ˆ 60%).72 (71. with boys being together with both parents longer (M ˆ 34%) than girls were together with both parents.99) 15 (14.05.181 INTERNATIONAL JOURNAL OF BEHAVIORAL DEVELOPMENT. 48) ˆ 10. thus conŽ rming both evolutionary and psychological assumptions. 48) ˆ 4.25) 275. It became evident that only a minority of fathers spent time exclusively with their young infants (N ˆ 13).005.04 (26.68) 52 (25. 2007 © 2002 International Society for the Study of Behavioral Development.com by stefan boncu on November 28. Therefore. timed and planned. and the time both parents were present. 54) ˆ 8.89)b 2. All these infants received more breast-feeding (M ˆ 31 min) than bottle feeding (M ˆ 7 min).19) 18. therefore.65) than boys (M ˆ 37. In the next step of data analyses we analysed the time mothers engaged in face-to-face interactions with their infants during the different social contexts we had analysed in the previous section. All rights reserved. The preference of Ž rstborns is in line with evolutionary and psychological expectations.29) 42 (11.38 (24. Regarding the time both parents were present a 2 (ordinal position) £ 2 (gender) ANOVA revealed a main effect for ordinal position. The psychological indicator of parental care in Western industrialised societies might be seen in facial social involvement. stressing that mothers prefer same sex infants. fathers’ primary care was excluded from statistical analysis.39 (12. a particular inclination and motivation for parental care can be assumed. Two of them were fathers of Ž rstborn boys and two were fathers of Ž rstborn girls.40) 30 (9.21) 19.182 KELLER AND ZACK / GENDER AND BIRTH ORDER observed when mother and father were present simultaneously.67) 29 (19. These comprise the total time she spent with the infant.20) 25 (19. SD ˆ 23.63 (51. p < . A main effect for gender.005. sleep. Typical for this economic situation is that women start reproduction in their late twenties. The time fathers engaged in face-to-face interaction with the infant was also computed for the total time he spent with the infant as well as for the time both parents were present.12 (53.61 (6. With respect to time allocation of both parents. 54) ˆ 10. fussiness.13) 40 (15. and three were fathers of laterborn girls.10) 9. This result yields a main effect of gender and supports the assumption derived from the psychological literature. This result is inconsistent with evolutionary and psychological assumptions.84) 95.47) 90.19) 8.46). Downloaded from http://jbd.65) 34 (28.49 (15.47. Differences in caregiving might.69. 47) ˆ 4.87) 25. and crying. Primary care by ordinal position and gender Primary care is deŽ ned as the time the infants were breast. three laterborn boys.41) 45.44) 14.as well as breast-fed.05 or lower).23) 71. Fathers of Ž rstborn infants engaged in face-to-face interactions with their infants far longer (M ˆ 28%) than fathers of laterborn infants did with their young offspring (M ˆ 8%).58) 102.42) 32 (31. one Ž rstborn girl.29) 124.g.92) 31 (24.54) Note: Means within a row with different subscripts differ signiŽ cantly (p < . the time she was alone with the infant.54 (12.48 (43. Because the decision to have a baby during this life stage is.25) 36 (15.78 (31.47) 33 (35.sagepub.33 (50.19) 24.11. This result does not support assumptions from both orientations. There was no main effect for ordinal position and no interaction effect..19 (29. With respect to face-to-face interaction with fathers during his total time of presence a 2 (ordinal position) £ 2 (gender) ANOVA revealed a main effect for gender. The period of time fathers were alone with the infant was excluded. in most cases.26)b 6. All infants who were enrolled in this study were healthy.60 (10. The six infants.and breast-fed were: one Ž rstborn boy. For illustrative purposes. and six infants were bottle. A 2 (ordinal position) £ 2 (gender) ANOVA yielded no signiŽ cant group differences. Ž rstborn boys were preferred over all other infants which is in line with evolutionary theory.52) 45 (14.51) 36 (21.17) 26 (19.13. F(1. computed as percentage of the duration of the respective context are presented in Table 4.07) 3 (3. not only be embedded in cultural belief systems (e.43) 16. p < . The samples were homogeneously composed from participants with an af uent middle class background.04 (19. Fathers’ face-to-face interaction. Only a few fathers (N ˆ 10) fed the baby. SD ˆ 17. We analysed group differences for the total nursing time (see Table 3).65 (14. F(1.96) 47 (12. demonstrated comparable state regulations of wakefulness. which was also the case for our participants. Means and standard deviations for the duration of face-to-face interactions with the infants. Discussion The present study focused on the effect of young infants’ gender and their birth position with respect to different aspects of parental care.81)a 30.05.01) 30 (23.36) 13 (19. and one laterborn girl.39 (46. F(1.29 (24.20.97) 19 (31. who were bottle. concerning gender development). three were fathers of laterborn boys.71) 10. revealed that mothers invested more time in feeding girls (M ˆ 53.28 (15. Face-to-face interaction with parents by ordinal position and gender Mothers’ face-to-face interaction.34) 12 (18. and did not differ with respect to the temperament as perceived by their mothers. Twentyone infants were bottle-fed exclusively. but also the intuitive calculations of investment decisions. Our data in fact reveal differences in maternal behaviours and especially in Table 4 Means (and standard deviations) of the percentages of dyadic face-to-face interaction with mothers and fathers during the time being present Firstborn With mother regardless of others’ presence With mother when father is present With mother when alone with mother With father regardless of others’ presence With father when mother is present Laterborn Boys Girls Boys Girls 35 (12.50 (9. because this social context only rarely occurred (see above).81 (21. Fathers signiŽ cantly engaged more in face-to-face interactions with their daughters (M ˆ 35%) than with their sons (M ˆ 19%). Not for commercial use or unauthorized distribution.34) 110. corresponding time in minutes is added in italics.08)a 22.005. 31 were breast-fed. . p < .26 (37.and bottle-fed by their mothers. the pattern of results is complex and supports the possible impact of in uences that can be related to proximate psychological and ultimate evolutionary considerations. reveal different results. our results underline that evolutionary considerations help the understanding of psychological processes and mechanisms which in uence differential parenting in modern urban societies.sagepub. With few exceptions (cf. Not for commercial use or unauthorized distribution. The Ž nding that fathers prefer daughters in terms of face-toface behaviour. for example. presence of fathers. there is a belief in Costa Rica that girls suck less strongly than boys which could explain longer feeding times for girls (Chavarria. & Runde.INTERNATIONAL JOURNAL OF BEHAVIORAL DEVELOPMENT. and face-to-face behaviour of fathers when mothers are also present. This preference is in line with both psychological and evolutionary lines of thinking and conŽ rms the results from existing studies also with German samples. parents’ intention in interactions with infants of that age is mainly to establish eye contact (Keller. and thus social desirability. This result is an interesting supplement to previous studies which indicated that the presence of others generally decreases 183 interaction with the infant (Lamb. Cohn. this is in line with evolutionary as well as psychological thinking. Yet. Leyendecker et al. it is difŽ cult to assess enough comparable families with healthy infants with an extensive observational programme within a one-year timespan. primary care. Also. This is especially necessary. Overall. our data support mainly the same sex hypothesis. The only signiŽ cant interaction effect concerns the simultaneous presence of mothers and fathers with their Ž rstborn boys. the analysis of behavioural initiatives might reveal more insight into the qualitative pattern of interaction. Jacobs & Moss. For them.com by stefan boncu on November 28. the study of comparable favourable and less advantaged socioeconomic contexts in different cultures could substantiate the pattern of Ž ndings. In particular. and face-to-face exchange. Including. Mothers usually have one year of maternity leave after childbirth and they spend most of their time with their children. One signiŽ cant constraint of our study is certainly the relatively small number of participants. This situation might be different for fathers who were all breadwinners in our sample. mechanisms inherent in parenting behaviours and their developmental consequences might elucidate differential treatment as shaping different self-conceptions. Parke & Tinsley. 1976. they are even more pronounced than in any other social context. personal communication). In terms of the main effect of gender. 1979. For further clariŽ cation it is important to vary the availability of resources. Although the results concerning the joint presence of mothers and fathers are mainly shaped by paternal behaviour. 2007 © 2002 International Society for the Study of Behavioral Development. 1990). It is interesting that there appears to be a difference between mothers and fathers concerning treatment of their infants: This might re ect socioecological factors in the socialisation pattern of small children in Germany.. For example. whereas mothers’ presence is in line with evolutionary considerations only. Loewer. 1987). Firstborns are preferred over laterborns in terms of presence of mothers. 2002. It is important to stress that we do not consider psychological and evolutionary considerations as contradictory which should be tested against each other. As can be inferred from verbal comments. In terms of fathers’ presence. it would be necessary to analyse. Manuscript received January 2000 Revised manuscript received March 2000 Downloaded from http://jbd. as caregiving routines in general and the participation of fathers in particular are in uenced by secular trends. Analyses of further psychological variables are needed to clarify these results. working mothers or single parents into the empirical design might elucidate the patterns of constraints. As we could demonstrate with our data. Firstborn boys receive most attention in terms of mothers’ and fathers’ simultaneous presence. Due to this special situation. Our data further reveal that the simultaneous presence of mothers and fathers constitutes an important social setting for differences of parental treatment. most studies assessed only brief observation periods whereas our results are based on extended observation periods. 1997). Facial engagement as an intensive psychological mode of caregiving might be in uenced by ideas about good parenting. presence. evolutionary thinking allows the formulation of predictions in which the evidence from psychological studies should be incorporated. . Our results underline that different parameters of investment and parental treatment have to be assessed. we could not analyse whether the gender of the Ž rst child in uences the treatment of the laterborn. there might only be a few con icting challenges for the distribution of their time. thus possibly qualifying this social context as especially salient for analysing differential treatment. What we term ‘‘psychologically’’ is mainly the description of a pattern which is post-hoc related to developmental goals. so that the participation belong to one sociohistorical cohort. expresses an unexpected complementary sex preference. The different modes we investigated. These results might be partly rooted in the dynamics of interaction between mothers and fathers and their intuitive negotiations of investment decisions and needs to be further explored in follow-up studies. Because of the small numbers within the cells. Moore. time might constitute a valuable resource with the consequence of more con icting tendencies for differentiated allocation of paternal time and effort. In order to understand these differences better. behavioural qualities as well. The inclusion of contexts varying with respect to availability of resources in other respects might further clarify interaction effects. However. It could be speculated that the equal distribution of facial engagement of mothers across the subsamples. as well as the unexpected preference fathers exhibit for their daughters in terms of visual engagement might result from counteracting preferential tendencies. the number of signiŽ cant Ž ndings indicates that the sample size was not overly detrimental. On the other hand. However. for example. the availability of time is a differential resource. parental ethnotheories and cultural belief systems have to be taken into account in order to better understand parenting strategies. In particular. 177–184 paternal behaviours which can be related to gender and sibling position of their 3-month-old infants. Most pronounced in our data is the main effect of birth order. Furthermore. Our data in fact indicate that fathers differentiate their presence as well as their facial engagement with respect to gender and birth position of their children. The context that we chose has allowed describing primarily main effects. Fathers’ display of facial exchange is most pronounced with Ž rstborn infants when the mother is also present as compared to all other groups of infants. in that mothers prefer their daughters in terms of presence and primary care and fathers prefer their sons in terms of presence. on the other hand. as well as quantitative terms like duration of behaviour. and Campbell (1997) demonstrated in a longitudinal design that mothers displayed more positive affect (warmth) with their secondborn children as compared to their Ž rstborns. 26 (2). All rights reserved. L. 2. M. Cronk. Gender.E. NJ: Rutgers University Press. (1973). sibling competition. Lamb. 1–37. In J. B. J. American Behavioral Scientist. & D. Food sharing on Ifaluk. Sisters and brothers. NJ: Erlbaum. age. R.) (1963). Women of Dakar and the surrounding area. The evolution of minds: Psychological and philosophical perspectives. & Turke.E.B.. 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