Coined by the 2015 Pixar film Inside Out, “core memories” are rare, vivid experiences that stay with us all our lives. In the film, core memories are portrayed as glowing orbs that are filed deep within the protagonist’s consciousness, forming the essence of who she is. When she loses them, she loses herself. 

Now, core memories have emerged as a hit theme on TikTok. Popular videos show brothers and sisters jumping into the ocean for the first time, sudden rainstorms after soccer games, babies and puppies sharing tubs of ice cream. And many of the videos come with a message of encouragement: Get outside and make some memories! 

The trouble is that core memories—at least as they are portrayed in Inside Out—are not a real psychological phenomenon. Seemingly important experiences...