A research project on toddler care indicated that the level of interaction toddlers have influences their naptime. At twelve months old, toddlers in the study with a less interactive daily schedule napped an average of one and a half hours more each day than those with a more interactive schedule. Given that naptime is crucial for a child's growth, caregivers might consider minimizing the level of interaction their toddlers experience. Which one of the following statements, if true, most seriously weakens the argument?