Sunday, March 03, 2013

Flashing Lights and Spinning Wheels

“Everything takes time. Bees have to move very fast to stay still.” – David Foster Wallace, Brief Interviews with Hideous Men 

Zen Buddhists put great emphasis on living in the present moment. "Be here now." Yet, can we exist anywhere but the present? The past is gone and the future has not yet happened, so where else could we be? 

Perhaps we should not be so certain, notes Jan Westerhoff in The New Scientist (February 20, 2013).  Sensory information reaches us at different speeds, yet appears unified as one moment. Nerve signals need time to be transmitted and time to be processed by the brain. And there are events – such as a light flashing, or someone snapping their fingers – that take less time to occur than our system needs to process them. By the time we become aware of the flash or the finger-snap, it is already history.

According to Westerhoff, our experience of the world resembles a television broadcast with a time lag; conscious perception is not "live". This on its own might not be too much cause for concern, but in the same way the TV time lag makes last-minute censorship possible, our brain, rather than showing us what happened a moment ago, sometimes constructs a present that has never actually happened.

Evidence for this can be found in the "flash-lag" illusion. In one version, a screen displays a rotating disc with an arrow on it, pointing outwards. Next to the disc is a spot of light that is programmed to flash at the exact moment the spinning arrow passes it. Yet this is not what we perceive. Instead, the flash lags behind, apparently occurring after the arrow has passed.

The explanation is that our brain is interpolating events from the past, retroactively assembling a story of what happened.  The perception of what is happening at the moment of the flash is determined by what happens to the disc after the flash.  This seems paradoxical, but other tests have confirmed that what is perceived to have occurred at a certain time can be influenced by what happens later.

All of this is slightly worrying if we hold on to the common-sense view that our selves are placed in the present. If the moment in time we are supposed to be inhabiting turns out to be a mere construction, the same is likely to be true of the self existing in that present.

Interesting point, but I don't think a moving dial and a flash of light is enough to convince anyone that the self does not exist.  However, this interpolation of events from the past, the story that we've retroactively assembled, is yet another example of samskara, the schema formed by our subconscious.  The Buddha taught that consciousness comes into being when we perceive the arising of schemata, and as consciousness is one of the essential element of a "self," the self is just another retroactively assembled story as subject to misinterpretation as the location of the arrow when the light flashes.

The neuroscientists who are conducting the time-lag and other psychophysical experiments would be better advised to investigate their own subjective experience of time and the self than to watch others look at flashing lights and spinning wheels.

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