A 10-year study by the Boulder-based non-profit LENA shows that the amount of talk with adults that babies experience in the first three years of life is related to their verbal abilities and IQ in adolescence. The study, published in Pediatrics, also found that two-way conversations in the 18- to 24-month age range could be especially important. The results showed that the number of conversational turns at 18 to 24 months accounted for 14 percent to 27 percent of the variance in IQ, verbal comprehension and vocabulary after controlling for socioeconomic status. LENA offers several programs based on the research, including two that are used locally near Boulder, Colorado.