https://www.scientificamerican.com/article/sorry-mom-and-dad-toys-cannot-supercharge-your-baby/

When Seth Pollak's son was a year old, he and his wife, Jenny Saffran, took a trip to the Babies “R” Us store near their home in Madison, Wis. They wanted to buy a teething ring—nothing special, just a frozen band to numb the baby's gums. Passing through the bears and bicycles, they found the correct display. They pulled a pricey package off the shelf, which read, “Promotes oral motor and language development.”