Lateral cradling preferences in men and women: results from a photographic study

Handedness as a major determinant of lateral bias in human functional cradling

Studies examining infant cradling have almost uniformly concluded with a general human left-side bias for cradling, indicating that people prefer to hold an infant to the left of their body. Explanations for the notion of the left-side cradling bias have traditionally been searched for in a variety of factors, for example, in terms of maternal heartbeat, genetic factors, in the form of an ear asymmetry where auditory information is perceived faster through the left ear, as a result of a right hemispheric functional specialization for perception of emotions and faces, and in identifying a motor bias of the infant, such as the tendency of newborn infants to lie with the face to the right when placed supine. Interestingly, handedness is generally considered an inadequate explanation for the lateralized cradling bias, despite it being an intuitively plausible one. In this brief review, I put forward the cradler's handedness as the most convincing and elegant determinant of the cradling bias. This explanation is consistent with a developmental cascades' framework where the cradling bias can be understood as the result of a multitude of factors across a range of levels and systems.

Asymmetries in social touch-motor and emotional biases on lateral preferences in embracing, cradling and kissing

In human social interaction, affective touch plays an integral role to communicate intentions and emotions. Three of the most important forms of social touch are embracing, cradling and kissing. These behaviours have been demonstrated to be lateralized, but the underlying mechanisms are still not well understood. Both motor and emotive biases have been suggested to affect laterality of social touch. We aimed to systematically investigate how motor preferences and emotive biases influence the lateralization of embracing, cradling and kissing within the same sample. Participants performed all three forms of social touch in neutral, positive and negative emotional conditions. Like a previous study, we found a rightward bias for embracing that was modulated by both motor preferences and the emotional content of the situation. Kissing and cradling were not influenced by motor preferences. In general, a negative emotional connotation of the situation led to a reduction of lateral biases in social touch, independent of the individual direction.

Hugs and kisses - The role of motor preferences and emotional lateralization for hemispheric asymmetries in human social touch

Social touch is an important aspect of human social interaction - across all cultures, humans engage in kissing, cradling and embracing. These behaviors are necessarily asymmetric, but the factors that determine their lateralization are not well-understood. Because the hands are often involved in social touch, motor preferences may give rise to asymmetric behavior. However, social touch often occurs in emotional contexts, suggesting that biases might be modulated by asymmetries in emotional processing. Social touch may therefore provide unique insights into lateralized brain networks that link emotion and action. Here, we review the literature on lateralization of cradling, kissing and embracing with respect to motor and emotive bias theories. Lateral biases in all three forms of social touch are influenced, but not fully determined by handedness. Thus, motor bias theory partly explains side biases in social touch. However, emotional context also affects side biases, most strongly for embracing. Taken together, literature analysis reveals that side biases in social touch are most likely determined by a combination of motor and emotive biases.

Human Left-Sided Cradling Preferences for Dogs

Photographs of men and women holding dogs were analyzed for side-holding preferences. A significant majority of women in dog-themed magazines held dogs on their left sides, similar to reports of women holding infants. Men did not show the same left-sided preference, which is also consistent with other studies. The implications of these results for various hypotheses about infant cradling behavior were discussed.

Newborn right-holding is related to depressive symptoms in bottle-feeding mothers but not in breastfeeding mothers

This study examines the relationships between infant holding preferences and maternal depression according to the newborn feeding mode. Links between depression and infant holding biases have been observed in mothers [Vauclair, J., Scola, C. (in press). Dépression, alexithymie et latéralisation dans la façon de porter un nouveau-né [Infant holding biases in relation to depression, alexithymia and laterality]. Annales Médico-psychologiques; Weatherill, R. P., Almerigi, J. B., Levendosky, A. A., Bogat, G. A., von Eye, A., & Harris, L. J. (2004). Is maternal depression related to side of infant holding? International Journal of Behavioral Development, 28, 421-427] but the fact that breastfeeding has never been studied in relation to these two factors is surprising as breastfeeding has some influence on depression (e.g., [Mezzacappa, E. S., Guethlein, W., Vaz, N., & Bagiella, E. (2000). A preliminary study of breast-feeding and maternal symptomatology. Annals of Behavioral Medicine, 22, 71-79]) and must also affect holding biases. Mothers who just gave birth (N=100) were tested few days after delivery. Measures of handedness, infant holding-side preferences, and level of depressive symptoms expressed by mothers (assessed with the CES-D scale) were collected via questionnaires. Asymmetries in emotional perception were assessed via a Chimeric Figure Task and a Dichotic Listening Task. Results showed that breastfeeding (1) reduced left-side bias for holding newborns and (2) was associated with lowest levels of depressive symptoms. Moreover, holding biases were related to maternal depression in bottle-feeding but not in breastfeeding mothers, namely that holding on the right-side while bottle-feeding was associated with higher levels of depressive symptoms. These results were not due to hemispheric specialization as auditory and visual asymmetries were similar between breastfeeding and bottle-feeding mothers. The discussion emphasizes the striking role of the early mother/child relationship's establishment on infant holding biases.

Lateralisation of emotion predicts infant-holding bias in left-handed students, but not in left-handed mothers

It has been shown that most human beings prefer to hold an infant on the left side of the body. Several factors may be responsible for this behavioural bias. The present study tested the role of emotion-perception asymmetries (assessed with a dichotic listening task) in infant holding-side preferences. In order to neutralise the influence of handedness, only left-handers were recruited. A sample of students was compared to a sample of mothers, with a view to demonstrating that hemispheric specialisation influences holding-side biases in left-handers only in a basic holding relationship (population of non-parents tested on an imagination task). The results confirmed the relationship between holding-side preferences and auditory-field advantages solely for students. The role of the holder's characteristics in determining of holding biases is discussed.

Handedness as a major determinant of functional cradling bias

Cradling is an interactive activity, involving a manual component that is very often an integral part of cradling. Cradling, while doing something else with the free hand, is referred to here as functional cradling. This study examined the relationship between a person's handedness and what arm he or she prefers to use when functionally cradling a baby doll that resembles a newborn infant. A total of 765 participants took part in the experiment, 403 women and 362 men, between the ages of 4 and 86 years. Left- and mixed-handers were actively recruited. The sample consisted of 64.3% right-handed, 24.7% mixed-handed, and 11.0% left-handed participants. The results showed a clear tendency for participants to cradle in their non-dominant arm (p < .001). Furthermore, this tendency increased with age and it was present in both sexes, although significantly stronger in women than in men. On the other hand, experience with young children through younger siblings and/or being a parent did not increase the likelihood to cradle in the non-dominant arm. It is concluded that humans have a clear functional cradling preference for the non-dominant arm because this enables the dominant arm to engage in other tasks. This might also explain why previous studies have reported a universal left cradling bias because a right-handed majority (intuitively) keeps the dominant hand free when cradling.

Infant holding biases and their relations to hemispheric specializations for perceiving facial emotions

Since Salk [Salk, L. (1960). The effects of the normal heartbeat sound on the behavior of the new-born infant: implications for mental health. World Mental Health 12, 168-175] reported a left-side preference for cradling an infant, several studies have attempted to elucidate the origin of this bias. Sex and handedness were the first variables tested but none of them is sufficient for explaining this bias. Manning and Chamberlain [Manning, J. T., & Chamberlain, A. T. (1991). Left-side cradling and brain lateralization. Ethology and Sociobiology, 12, 237-244] proposed that the explanation had to do with hemispheric specialization of emotions and suggested that the mother could better monitor her infant's emotional state when holding on the left side than on the right side. Moreover, the infant could monitor its mother's emotional state, since the most expressive side of mother's face (the left) is visible to the infant. We used two Chimeric Figures Tasks in order to assess (1) the preferred visual field for perceiving an emotion and (2) the most expressive side of the face. Holding biases were measured in a concrete situation using an infant doll. Our main objective was to assess the relation between the asymmetric visual perception and the holding direction in a large sample of university students. We replicated a left-holding preference (66%) in our sample and found an effect of participants' holding posture and a limited effect of laterality but no effect of sex. The most significant finding concerns the links between the preferred visual field and the preferred holding side. This effect was observed in the sample of women, in right-handers, and in the sub-group of participants with care-giving skills. These findings suggest a leading role for the right hemisphere for side of holding.

Maternal cradling and infant nipple preferences in rhesus monkeys (Macaca mulatta)

This study investigated lateral biases in nipple preferences, maternal cradling, carrying, and retrieval in 41 rhesus macaque (Macaca mulatta) mother-infant dyads living in two captive social groups. Observations were made during the first 6 weeks of infant life using a combination of scan sampling and ad-libitum sampling techniques. Infants exhibited a significant left-nipple preference in the first weeks of life but the bias decreased with infant age. Mothers showed a left-arm bias in carrying their infants but no significant lateral bias in cradling or retrieval. Our results suggest that the left-side cradling bias reported in studies of humans and some other primates reflects a bias in the infant's nipple preference rather than in maternal behavior. The infants' preference for the left nipple is consistent with both Salk's (1960) heartbeat hypothesis and with more recent hypotheses linking this lateral bias with brain asymmetry and hemispheric specialization for mother-infant communication.

Lateral cradling preferences in children

Lateral preferences for cradling a doll and for holding a package were investigated among children from 2- to 6-yr-old. Results showed a preference for holding a baby on the left side of the body in children as young as 3 yr. old. The data favour the hypothesis of an early emergence of this pattern of behavior in the human ontogenesis.