Sandrine Ceurstemont, editor, New Scientist TV
Think you're living in the moment? You could actually be experiencing another time.
A brain trick called the flash-lag illusion shows how we don't always perceive the present. This version, created by Eiji Watanabe from the National Institute for Basic Biology in Okazaki, Japan, presents a moving cube occasionally accompanied by a flashing twin. When the second box appears, it's really lined up with the moving cube yet it seems to lag behind. A second example uses a gear animation to show how a flashing piston looks out of sync with another that's shifting up and down.
The illusion was thought to be caused by our brain extrapolating into the future: it can accurately anticipate the position of the moving cube because it follows a predictable path, but it falls short when assessing where the flashing cube is due to the time it takes to process a stimulus.
Recently David Eagleman of the Salk Institute in La Jolla, California, and colleagues found that our brain is reaching back into the past instead. It waits to see what happens right after the flash before determining the cube's position: changing the trajectory of the moving object after the blinking can influence where it's perceived.
The effect is interesting because it gives insight into our notion of self and whether we exist in the here and now. To find out more, check out our feature, "The self: You think you live in the present?".
If you enjoyed this post, see how to move a dot with your mind or how to affect an object's motion by changing your gaze.
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