A study examining cultural characteristics of infants’ behavior found that Korean and Japanese infants cry more when separated from their mothers and left alone in an unfamiliar room, compared to U.S. and Czech children. The paper was published in the International Journal of Behavioral Development.

The main theoretical framework in psychology used to explain emotional bonds between humans and their importance throughout life is attachment theory, proposed by John Bowlby in the mid-20th century. According to this theory, emotional attachment patterns begin developing in infancy through interactions between the infant and its caregiver(s).

One of the main research procedures for assessing the quality of infants’ attachment to their caregivers is the Strange Situation Procedure. This procedure was developed by Mary Ainsworth, a famous 20th-century attachment researcher, and her colleagues to observe how children use a caregiver as a secure base and how they react to separation and reunion.

In this procedure, a child is placed in an unfamiliar room with toys, first with the caregiver present. Then a stranger enters, the caregiver leaves, the child is briefly left with the stranger or alone, and the caregiver later returns. The key observations are whether the child cries during separation and how they behave after the caregiver returns.

For example, securely attached children are usually upset by separation but are comforted by the caregiver and return to play after the reunion. In contrast, avoidantly attached children tend to show little distress and may ignore or avoid the caregiver at reunion.

Another classification is “insecure-resistant” (also called ambivalent) attachment; these children tend to cry intensely during separation and resist being comforted by the caregiver upon reunion. Finally, children with a disorganized attachment pattern might be confused, contradictory, or display apprehensive behavior toward the caregiver after reunion.

Study author Tomotaka Umemura and his colleagues note that, although the Strange Situation Procedure emphasizes the importance of context, previous studies have not explored the cultural characteristics of infants’ behavior in detail. Notably, past research has disproportionately classified East-Asian infants as having “insecure-resistant” attachment styles based on their highly distressed reactions during the procedure.

The researchers hypothesized that this intense crying might reflect cultural differences rather than actual insecure attachment. In East-Asian cultures, babies are rarely separated from their mothers in daily life, meaning the Strange Situation Procedure is deeply unfamiliar and frightening, rather than just mildly stressful. To test this, the researchers set out to examine whether East-Asian infants differ in their levels of crying during the procedure compared to Western infants.

The researchers compared the recorded behavior of infants from several previously published studies. Western infants were represented by a group of 106 U.S. infants from a 1978 study carried out by Ainsworth and her colleagues, and by a group of 66 Czech infants from a 2023 study. East-Asian infants were represented by a group of 87 Korean infants from Taegu, a group of 45 Japanese infants from Sapporo, and a group of 81 Japanese infants from the Hiroshima area. The Korean group was from a 2005 study, while the Japanese data were from studies published in 2018 and 2022.

The study authors report that research assistants coded the crying behaviors of the East-Asian and Czech infants and recorded the length of each Strange Situation Procedure episode. The information about the crying behavior of the U.S. infants came from Ainsworth’s original 1978 book.

Results showed that U.S. and Czech infants generally cried less than Korean and Japanese infants. More specifically, when the infants were separated from their mothers and left completely alone, the Japanese and Korean infants cried significantly more than the U.S. infants. Furthermore, when a stranger entered the room to comfort the alone infant, the East-Asian infants cried significantly more than both the U.S. and Czech infants.

However, despite these intense reactions during separation, the infants did not show significantly different levels of crying once they were reunited with their mothers (with the exception of one of the Japanese groups, which cried more compared to the Czech and U.S. infants during the final reunion episode).

“When infants were separated from their mothers during the second separation (remaining alone and, subsequently, with a stranger), East-Asian infants were more likely to show higher levels of crying compared to Western infants. These results were consistent across three East-Asian samples from Korea and Japan. Despite these higher levels of crying during the separation episodes, East-Asian infants did not show different levels of crying in the reunion episodes compared to Western infants, except for the first sample of Japanese infants that showed higher levels of crying compared to Western infants,” the study authors concluded.

The study contributes to scientific knowledge about cross-cultural differences in infants’ behavior and suggests that researchers should be cautious about classifying highly distressed non-Western infants as “insecurely attached.”

However, it should be noted that the data on U.S. infants were collected almost half a century before the newest data used in the study. Cultural drift might have occurred during this period, limiting the generalizability of those results to the modern U.S. population.

Additionally, the two Japanese infant groups differed markedly in crying in some situations, even though they represent the same culture. Similarly, in some episodes of the study procedure, the Czech children’s crying did not significantly differ from the East-Asian infants. Because of this, any inferences about cultural differences drawn from this study should be made with caution, as the observed differences may reflect variations in study procedures or differences between these specific groups of infants, rather than stable differences between cultures as a whole.

The paper, “Crying in the Strange Situation Procedure: Comparisons Between East-Asian and Western Infants,” was authored by Tomotaka Umemura, Mi Kyoung Jin, Kiyomi Kondo-Ikemura, Lenka Lacinová, Kyonosuke Handa, Yu Xu, and Kota Yoshikawa.