Children have many early abilities that we didn't know exactly. When we studied cognitive development, we realized that children get many abilities earlier than we anticipated. Among these abilities such as object concept, number concept, and person concept, I think I would remember children's preference for reliable and accurate source informants. I was surprised by children's ability that they can distinguish who is reliable informant and even prefer the informant when I studied cognitive development. This ability seems high-developed ability than any others to me.
This resulted from one experiment. First, an experimenter presented children with two speakers who differ in their reliability for 3 or 4 times for familization. One person was consistently naming object accurately, the other was consistently miss-naming the object. Then the experimenter asked explicit judgment question, asking children to indicate the speaker who was not very good at naming things. Finally, the experimenter asked children to request and endorse information from one of the speakers. The result was that even a 2-year-old child preferred more reliable and accurate source informants. According to this kind of experiments, psychologists realized that cognitive development emerges more continuous and earlier than my thought and previous thought of Piaget.