A recent analysis of toddler education indicates that the level of interaction children have during playtime influences their cognitive development. At two years old, toddlers in the study who engaged in less interactive playtime demonstrated an average of three points higher on cognitive assessments than those who had more interactive playtime. Given the importance of cognitive development in early childhood, educators might consider reducing the level of interaction during playtime. Which one of the following statements, if true, most seriously weakens the argument?