Infrared imaging uncovers emotional sensitivity in 10-month-old babies

A new cross-cultural study published in Developmental Science has demonstrated that infants as young as 10 months old display measurable emotional responses to the distress of their peers, offering compelling evidence that the roots of empathy emerge within the first year of life.

Contagious crying — where one infant’s distress triggers distress in another — has long been recognized in developmental psychology. However, previous studies of contagious crying have mostly focused on Western populations and often did not rule out whether babies were simply reacting to loud or jarring sounds.

Led by Zanna Clay from Durham University in the United Kingdom, the researchers in this study were particularly interested in teasing apart whether babies’ reactions were rooted in genuine emotional empathy or were simply startle responses to a harsh noise.

The team also wanted to explore whether cultural differences in upbringing, such as being raised in larger, more communal households versus smaller, nuclear families, influenced infants’ emotional sensitivity.

To do this, Clay and colleagues exposed 313 infants, aged between 10 and 11 months, to four types of noise: babies crying (negative sound), babies laughing (positive sound), babies babbling (neutral sound), and an artificial sound similar in harshness to crying but devoid of emotional meaning.

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While the infants listened, researchers used advanced infrared cameras to measure subtle changes in the temperature of the babies’ noses — a marker of emotional arousal. They also recorded the babies’ facial expressions to capture visible signs of emotional reactions.

The researchers discovered that infants demonstrated bigger shifts in nose temperature when listening to crying and laughing than when hearing the artificial noise. Crying also evoked a larger change in nose temperature compared to the neutral sound of babbling. Additionally, infants demonstrated stronger behavioral responses to crying compared to both the artificial sound and laughing.

Overall, crying triggered the strongest responses both emotionally and behaviorally, suggesting that babies aren’t just reacting to loudness — they are feeling something in response to the emotional content.

The study also found some cultural differences. Babies from the United Kingdom showed greater physiological reactivity than those from Uganda, although all groups showed the same basic pattern of emotional contagion. The researchers speculated that “Ugandan infants have more regular exposure to [infant noises], due to differences in household size and composition and more distributed caregiving. In contrast, the United Kingdom infants … were cared for exclusively in the home environment by parents on parental leave and did not attend nurseries. Increased exposure might have thus led to Ugandan infants being more habituated to noise disturbances, including infant signals, and thus correspondingly less physiologically activated.”

However, the researchers acknowledged some limitations. The direction of temperature change (whether it increased or decreased) was not clearly linked to whether an emotion was positive or negative. Also, while great care was taken to select culturally appropriate sounds, the study mainly used audio clips from Western infants.

The study, “Contagious Crying Revisited: A Cross-Cultural Investigation Into Infant Emotion Contagion Using Infrared Thermal Imaging,” was authored by C. Vreden, E. Renner, H. E. Ainamani, R. Crowther, B. Forward, S. Mazari, G. Tuohy, E. Ndyareeba, and Zanna Clay.