Over my career as a neuroscientist and neuropsychiatrist, I've become convinced that our brain's organization and functional activity powerfully influence our judgments and conclusions about topics traditionally explored by philosophers. Included among these topics are time, cause-effect, simultaneity, perception, logic, and free will. Our understanding of these concepts can be greatly enriched by taking into account several important recent discoveries from neuroscience. Consider, for instance, how our spatial experience influences how we think about time.
Imagine that you've just received this email: "Next Wednesday's staff meeting has been moved forward two days" On what day would you appear for the meeting now that it has been rescheduled?
Your selection of either Monday or Friday is determined by whether you are operating under what psychologist and neuroscientist Lera Boroditsky terms an ego-moving perspective or a time-moving perspective. If you think of yourself as moving forward through time (the ego-moving perspective), then moving the meeting forward means moving it in your direction of motion--from Wednesday to Friday. But if you conceive of time as coming toward you (the time-moving perspective), then moving the meeting forward means moving it closer to you--from Wednesday to Monday.
During her tenure at MIT's Department of Brain & Cognitive Sciences, Boroditsky put that "moved forward" question to hundreds of people under varying circumstances. She discovered that the answers depended very much on what people were doing when they were questioned. People who had traveled to an airport to pick up an arriving passenger were about equally likely to pick Monday or Friday. In contrast, the arriving passengers, having experienced themselves during their flight as moving forward from their initial to their final destination, overwhelmingly selected Friday.
Boroditsky's experiment suggests that our brain's processing of time is closely coupled with how we envision ourselves in space. To see this, simply substitute the word push for move and the sentence becomes disambiguated: "Next Wednesday's staff meeting has been pushed forward two days." While moved can refer to movement in several different directions depending on one's perspective, pushed nearly always implies movement in a forward direction. When we push something, we use the muscles of our arms and trunk to propel the object away from us in a forward direction.
The linking of spatial motion to our understanding of time comes as a surprise to anyone familiar with our brain's organization. Spatial and temporal information are processed differently within the brain. The frontal and parietal lobes, important in spatial processing, are located, respectively, behind the forehead and toward the top of the skull. Temporal information, in contrast, doesn't really have a clearly defined location in the brain.
But Albert Einstein wouldn't be surprised at Boroditsky's findings. As he famously established, time's passage depends on the location and circumstances of time measurement.
A time discrepancy between clock time and subjective time can be demonstrated in the laboratory. If I ask you to press a button and hold it for exactly five seconds, your response may vary by as much as 20 percent from one testing to another. If I ask you to hold the button for 50 seconds, you will on average do so within a range of 40 or 60 seconds--again a variation of 20 percent.
Attention is the most important variable influencing our appreciation of the passage of time. The closer attention we pay to it the slower it seems to go (a "watched pot never boils"). But there's a paradox here. While we may experience the passage of time as agonizingly slow when we're doing something like waiting for a pot to boil or sitting in a doctor's waiting room, we're likely to underestimate rather than overestimate the duration when we're later asked to guess how much time actually passed.
In an experiment illustrating this, people watching an action movie experienced time passing faster than people sitting in a waiting room. No surprise here. Yet when the two groups were later asked to estimate how much time had actually passed during these two experiences, the results were surprising. Despite their subjective feeling that time had passed quickly, the movie watchers later estimated their elapsed time at about 10 percent longer than the waiting-room group.
The explanation for such paradoxical findings, according to John Wearden of Keele University in Staffordshire, is that the two groups based their time assessment on the amount of information processed by their brains. In the waiting room, not much was happening and time seemed to drag on. But later, the time span seemed shorter because not much had happened and as a result little information was processed. For the viewers of...