3. First-born children tend to develop language skills faster than their younger siblings. One possible explanation for this phenomenon is that first-borns have undivided attention from their parents. If this explanation is correct, then it is also reasonable that twins should show slower language development than single children and triples should be even slower. Davis (1937) found exactly this result. The following hypothetical data demonstrate the relationship. The dependent variable is a measure of language skill at age 3 for each child (high scores indicate better language skill) Type of first-born Single child Twin Triplet 9 4 6 8 6 2 11 7 5 7 4 10 9 8 10 8 a. In this study, identify an IV and a DV (1)