A recent analysis of toddler care indicated that the level of interaction toddlers have during the day influences their nap duration. At twelve months old, toddlers in the analysis with a less interactive daytime schedule napped an average of one hour longer each day than those with a more interactive schedule. Given that napping is crucial for a toddler'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?