They Forgot Their "Baby"?!: Factors That Lead Students to Forget Their Cell Phone

Remembering intentions is critical for daily life, yet errors happen surprisingly often, even when there are fatal consequences (e.g., forgetting a baby in a car). To understand how people can forget personally important intentions, we took 192 students' cell phones while they participated in an unrelated experiment. We examined (a) how often students forgot to retrieve their cell phone when they left the lab compared to an experimenter-relevant task that required returning an activity tracker that we attached to their clothes to "monitor their amount of fidgeting" during the experiment and (b) whether it mattered if the instructions were explicitly encoded or not. Students only forgot the tracker 10%-13% more often than their cell phone, and explicit encoding did not reduce forgetting; neither did longer, more distracting ongoing tasks. Between 60% and 70% of participants said the intention "popped into mind." We suggest that prospective memory intentions are "autonomically" encoded, yet even explicitly encoded, personally important tasks are forgotten at surprising rates. General Audience Summary How do people forget personally important intentions, like forgetting your sleeping baby in the back seat when you leave the car (or forgetting to turn off appliances or bring your cell phone, keys, etc. with you, for that matter)? We suggest that such intentions are autonomically encoded by the mind and brain by default, yet even when intentions are explicitly encoded forgetting happens surprisingly often, and it is not clear why. To understand what causes forgetting, we took ∼200 students' cell phones from them when they came into our labs to participate in an unrelated experiment. Students forgot their cell phones at surprising rates compared to a control condition, and it did not matter (a) how students formed or "encoded" the intention, (b) how long and involved the other experiment tasks were, or (c) if they said they thought of the intention during their other, ongoing tasks. Students who said the intention spontaneously "popped into mind" at the right time were less likely to forget than those who did not. This study suggests that forgetting occurs when environmental cues fail to elicit spontaneous retrieval at the appropriate moment, regardless of whether or not intentions are explicitly encoded. This study should help inform the public and judicial system about what does and does not cause such prospective memory errors to happen-even those with tragic