Stevenson M B, Leavitt L A, Roach M A, Chapman R S, Miller J F
J Psycholinguist Res. 1986 Sep;15(5):451-61. doi: 10.1007/BF01067725.
The speech of mothers and their 1-year-old infants was compared in the home and in the laboratory playroom. The home and laboratory settings were similar for measuring the number of actual words that infants spoke and were similar for measuring the complexity of the mother's speech, including the number of different words, the type-token ratio, and the length of the utterances. Infants vocalized at similar rates in the two settings, but mothers spoke at a faster rate in the laboratory playroom. The usefulness of a preliminary warm-up period was supported by the finding that, for the second half of the sessions, mothers slowed their rate of speech and increased the complexity of their speech.
研究人员对母亲及其1岁婴儿在家庭环境和实验室游戏室中的言语进行了比较。在测量婴儿实际说出的单词数量以及测量母亲言语的复杂性（包括不同单词的数量、类符-型符比和话语长度）方面，家庭环境和实验室环境是相似的。婴儿在两种环境中的发声频率相似，但母亲在实验室游戏室中说话的速度更快。对于后半段会话，母亲们放慢了语速并增加了言语的复杂性，这一发现支持了初步热身期的有效性。
