Infants' exploration of scented toys: effects of prior experiences

To evaluate breastfed infants' responses to scented objects, we videotapedthe facial and bodily reactions of sixty-three infants as they explored, insuccession, three toys that were identical in appearance but different intheir characteristic odor. Two of the toys were scented with odorantspreviously shown to be transmitted to human milk, one with ethanol and theother with vanilla, whereas the third toy was unscented. Each videotape wassubjected to frame-by-frame analysis to measure a variety of behaviors thatare considered either to be exploratory in nature in that they lead toperceptual information about the object or to reflect the infants' hedonicreaction. Analyses of these behaviors revealed that the infants looked moreand vocalized less in the presence of the vanilla-scented toy and spentless time manipulating the ethanol-scented toy when compared with theunscented toy. Moreover, differential exposure to the odors of ethanol andvanilla, as indicated by differential consumption of alcohol by a parent oruse of vanilla-scented product by the mother, was related to differentialresponses to these odors. These findings suggest that human infants areable to detect and retain information about the chemical features of theirenvironment.