Rapid change in lexical development in comprehension and production.

Twenty-four infants were given word comprehension tests at 2-month intervals from 14 to 22 months. For each word, the child observed 2 slides and was prompted to look at 1 named by the experimenter. Visual fixation following the prompt was compared with fixation during a preprompt baseline to calculate a word comprehension score reflecting increase of attention to the referent independent of initial salience. The month-to-month change in comprehension scores revealed a spurt or surge for some but not all children, with the largest number of spurts occurring in the 20-22 month interval. For a subset of children (n=18), parents maintained diaries of spojen words. For a statistically significant number of children, the presence of a comprehension spurt was associated with the presence of a production spurt