Analysis of the olfactory capacity of healthy children before language acquisition

The absence of a method for evaluating the olfaction of infants and children without structured language led us to perform a longitudinal study of the behavioral responses of very young children. The aim was to establish a tool for verifying a child's olfactory ability during a pediatric examination. A total of 107 subjects were observed and filmed during a regular olfactory activity. Three years of filmed observations were analyzed and showed three types of stable behavioral responses that we consider to be specific to olfactory stimulus: modification of respiratory rhythm, fixed stare, and decrease of mobility. These responses were observed for 98% of the subjects in 100% of the first presentations of the odorized tissue. Response time was not influenced by age, socioeconomic situation, or position in the family, but it was influenced by ethnic background. These responses constitute items allowing the first step of an objective assessment of a prelanguage child's olfaction without the subject's verbal participation.