Nevertheless, recent studies have begun to question whether incidental instruction through book reading may be substantial enough to significantly boost children's
oral vocabulary
development.19 Several meta - analyses, for example, have reported only small to moderate effects of book reading on vocabulary
development.20 One group of researchers examined the added benefits of dialogic reading, an interactive reading
strategy, on children's vocabulary growth and reported only modest gains for 2 - to 3 - year - olds.21 Further, these effects were reduced to negligible levels when children were 4 to 5 years old or when they were at risk for
language and literacy impairments.