Analysis of a one-year-old's lexical development suggested factors causing overextensions: using known words for more recently acquired or unknown words; expressing incomplete knowledge of defining features of two or more similar meaning words; producing overextensions of preferred words; using phonologically simpler more than difficult words; and…

Investigated the relationship between children's failures to produce unambiguous utterances and the mental effort demands in children (ages five, six, seven, and nine years), using finger-tapping and message production tasks, separately and simultaneously. Findings suggest that the relative effort requirements of communication decrease with…