快猫短视频

EVER glanced at a clock and felt like the second hand takes longer than
normal to move? Now we know why.

According to Kielan Yarrow and his colleagues at the Institute of Neurology
in London, the phenomenon happens because our brains fool us into thinking we
have been looking at the second hand since just before our eyes moved to look at
the clock. So we think we鈥檝e been looking at it for longer than we actually
have. This happens any time we move our eyes, Yarrow says, but is only
noticeable when we look at something that shows the passage of time.

Yarrow鈥檚 team asked 30 volunteers to glance at a timer. As they did, it
started clocking up the seconds. Sneakily, the team varied the length of time
the initial 鈥�1鈥� stayed on the screen. By asking the volunteers to tell them when
this was visible for the same amount of time as the genuine seconds that
followed, they could gauge how long the volunteers actually perceived it to
last.

The team found the volunteers consistently felt it was displayed for longer
than it actually was鈥攕tarting from about 50 milliseconds before their eyes
had even begun to move. 鈥淭he purpose of this is one of the most puzzling
things,鈥� Yarrow says. Since the brain can make out very little during the actual
eye movement, it is as if it assumes a second hand, say, stays put throughout,
to smooth out our perception.

Researchers already knew that we only perceive events some time after they
occur, says Yarrow. According to his results, the lag is at least 140
milliseconds.