Diamond says the issue involves two parts of a person’s working memory: prospective and semantic. Prospective memory helps us remember to do something in the future, while semantic allows drivers to make the trip from work to home on “autopilot,” where they arrive without remembering clear details of how they got there.
Prospective and semantic memories work together to help us make changes to our routines; these changes could include things such as “drop off the baby at day care” or “stop for groceries on the way home.” When the working memory fails, such as when we’re distracted or stressed, there can be catastrophic implications, Diamond says. He gave examples of situations where critical safety steps can be overlooked, such as a surgeon leaving tools in a patient, a pilot not setting the wing flaps for landing, and caregivers forgetting that there’s a baby in the car.
“The habit brain system is a great convenience that allows us to go into autopilot,” Diamond says. “The beauty of it is that we don’t have to remember every turn, but the problem is that it’s actually guiding our behavior. When it guides our behavior, it suppresses the other part of the brain that is supposed to remind us of additional information.”
“We have to accept the fact that our brain multitasks. And as a part of that multitasking, the awareness of a child can be lost,” Diamond says. “We have to accept that the human memory is flawed. That includes when loving, attentive parents lose awareness of their children when they are in a car.”
Diamond has studied many heatstroke cases and points to common factors: stress, sleep deprivation, and change in routine.
Many times, when a child died, there had been a change in the day’s routine, Diamond says. For example, a parent who wouldn’t normally be responsible for day-care drop-off might have been given that task that day. Because our brains recognize a pattern for the day, this parent would drive to work as usual, even though the baby was along for the ride. And unless there was an external cue, such as seeing the diaper bag or hearing the baby, the parent’s brain would continue on autopilot and could even create a false memory that the child is safely at day care, Diamond found. Sleep deprivation and stress can also increase the potential for a working-memory failure.
Conflicts between semantic and prospective memory are normal, Diamond says. His research has shown that they happen to everyone—not just parents and caregivers—on almost a daily basis. The added stress, distraction, and sleep deprivation that parents often face can contribute to tragic situations.