The raid that killed Osama Bin Laden "was the longest 40 minutes of my life," said President Obama in a 60 Minutes interview that aired Sunday, "with the possible exception of when Sasha got meningitis when she was three months old and I was waiting for the doctor to tell me that she was all right." What makes some minutes feel longer than others?
Emotion and novelty. Scientists are still hunting for the neurological underpinnings of time perception, but they have begun to uncover some patterns in how our brains stretch and shrink durations. Negative emotions like anxiety, depression, and fear tend to slow things down, while positive emotions speed them up—at least while they're happening. (Time flies when you're having fun.) We also tend to remember unpredictable, complex events as taking longer than simple and straightforward ones. When study participants see the same photograph flashed over and over again for one second at a time, its first appearance seems to last an extra-long time. And when a different photograph is dropped into the predictable sequence, that image seems to stick around a little longer, too.
Much of the research on time perception has focused on brief events, like those tested in the oddball-image experiments. But what evidence we do have about the experience of longer durations—like Obama's interminable 40 minutes—suggests that negative emotions and novel stimuli have a similar effect, and create an illusory slowing of time.
Researchers who study the perception of minutes and hours like to distinguish between two forms of temporal cognition. Your sense of how long something takes can either be "prospective," which refers to how it feels (or how you remember its feeling) at the time, or "retrospective," which refers to how you feel about it after the fact. In general, time feels slower (in prospective terms) when you're nervous or scared, or when you're waiting for something to happen—the "watched pot never boils" phenomenon. Obama described the scene in the situation room as being "very tense" with "big chunks of time in which all we were doing was just waiting." Given that environment, it makes sense that he would have felt time slow down. Same goes for when he was waiting to hear about Sasha's meningitis.
The "longest 40 minutes of my life" description also makes sense as a retrospective assessment. When we think back on past experiences, those periods that were filled with intense and unpredictable stimuli tend to get stretched out. In general, the more distinct, meaningful memories you've stuffed into a given time span, the longer it feels. Anxiety plays a role here, too. One study found that medical trainees remembered a stressful heart-attack simulation as taking about 10 percent longer than it actually did. So Obama's recollection of his time spent in the situation room might reflect the dramatic series of events and fluctuating emotions he experienced there.
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Explainer thanks Richard A. Block of Montana State University and David Eagleman of the Baylor College of Medicine.