New research from the Monell Center reveals that children begin using olfactory information to help guide their responses to emotionally-expressive faces at about five years of age. The findings advance understanding of how children integrate different types of sensory information to direct their social behavior.
"Even though we may not be aware of it, the sense of smell influences how adults process emotional and social information to guide their decisions and behavior. Our findings establish that, beginning at the age of five, smell also influences children's emotional decisions," said cognitive neuroscientist Valentina Parma, PhD, one of the study's authors.
In the study, published online ahead of print in Developmental Science, 140 children between three and eleven years old were invited to participate in the research while visiting a local children's museum. Each child was exposed to one of three odors, either rose, fish, or blank, for three seconds. Immediately afterwards, the child saw a screen containing photographs of two faces, one happy and the other disgusted, and was asked to select one. Both facial expressions were from the same person. Afterward, the children rated the pleasantness of the odor.
The findings showed that children under the age of five tended to choose the happy face, regardless of the associated odor or how they rated its pleasantness.
However, beginning at age five, the odor influenced the children's decision of which face to select. Specifically, the older children based their selection on whether the visual and olfactory cues were emotionally similar; for example, the happy face was selected more frequently when paired with an odor rated as pleasant. Similarly, exposure to the unpleasant fish odor increased the likelihood of choosing the disgusted face.
"Now that we know that children as young as five years old use smells to make emotionally-based decisions, it may be possible to use this information in educational settings to guide social behavior," said Parma.
Moving forward, the researchers intend to explore whether this same developmental path applies to children with autism spectrum disorder. If so, the sense of smell might represent a useful tool to complement social and emotional treatment options.
Parma also commented on the value of conducting the research on site at Philadelphia's Please Touch Museum, a children's museum focused on creating learning opportunities through play.
"Taking the research outside the lab benefitted the museum, the local community and the researchers," said Parma. "The Please Touch Museum was able to provide children and parents with the opportunity to interact with scientists and learn about the research process. In turn, the research team established that we could conduct the research outside the laboratory setting without sacrificing methodological standards. This allowed us to enroll and test hundreds of children within a short period of time. It was a win for all involved."
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