Preverbal infants prefer characters that help others in achieving a goal (e.g. climbing up a hill), but how this preference is established remains unknown. In current study, we examined physical and emotional outcome hypotheses by presenting 6- and 10-month-old infants a social interaction similar to what was used in Hamlin et al. (2007). During the learning habituation stage, an agent emotionally comforted or upset a climber by pushing it up (helped) or down (hindered) the hill (physical outcome). On a new platform, we found that 10-month-old infants looked significantly longer when the climber approached the comforter who previously made the climber laugh regardless of what physical outcome was. This indicates infants’ prioritization of emotional over physical outcome and their consideration of a third party’s internal state in forming a social preference, which was absent at 6-month-olds. This leads to the conclusion that this prioritization is unlikely to be innate.