How to Change: The Science of Getting from Where You Are to Where You Want to Be

by Katy Milkman

According to one recent study, the average adult forgets three things each day, ranging from pin numbers to chores to wedding anniversaries. We’re so forgetful, in part, because it’s difficult for information to stick in our brains, especially if we’ve only thought about it once or twice. The German psychologist Hermann Ebbinghaus demonstrated how quickly humans forget in a classic study published in 1885. He attempted to memorize different sets of nonsense syllables and then tested his recollection at varying time intervals. With data from this experiment on his own memory, Hermann estimated that forgetting follows a roughly exponential decay function. We forget nearly half of the information we’ve learned within twenty minutes. After twenty-four hours, about 70 percent of it is gone, and a month later, we’re looking at losses of approximately 80 percent. This basic pattern has also been replicated in more recent studies using similar experimental procedures.