What happens if you lie to a child during language acquisition? During language acquisition a child can learn 20 words a day. What would happen if the parent decided to lie to the child during this time so that whenever the child said "what that?" the parent made up a random word.

Would this permanently stay in the child's mind forever? Or would the child just learn the "real" word from everyday speech?

As an aside, for years I thought the word "modest" meant the opposite of what it means. Because it is only ever said sarcastically. As in "wow, your sooooo modest!" And that's just one word.
You would need a conspiracy of many people to prank a child with this kind of thing, because kids are really good at tracking the information value of sources. If you give a different random word every time they'll discount you as an information source, if you give the same random word every time they'll learn it... and use it only with you (more or less, but increasingly so with age/experience.) See Birch et al. (2008) for more details.

You might also have fun with the literature on early bilingualism, which is basically this situation, right? Kids are phenomenal at this. See for example Liberman et al. (2017).


Birch, S. A., Vauthier, S. A., &amp; Bloom, P. (2008). [Three-and four-year-olds spontaneously use others’ past performance to guide their learning.][] Cognition, 107(3), 1018-1034.
Liberman, Z., Woodward, A. L., Keysar, B., &amp; Kinzler, K. D. (2017). Exposure to multiple languages enhances communication skills in infancy. Developmental science, 20(1), e12420.