The only statistically significant difference discovered was that only children possessed a higher achievement motivation, which Denise Polit and Toni Falbo attributed to their greater share of parental resources, expectations, and scrutiny exposing them to a greater degree of reward, and greater likelihood of punishment for falling short. A second analysis by the authors revealed that only children, children with only one sibling, and first-borns in general, score higher on tests of verbal ability than later-borns and children with multiple siblings.[28]