Friday Illusion: Star Trek effect beams triple trick

Sandrine Ceurstemont, editor, New Scientist TV

No, it's not science fiction: a new illusion that looks like a flight through space simultaneously tricks your brain in three different ways.

Watch the moving white dots and their shadows as they move forwards and backwards. They should appear to change in contrast, grow and shrink in size and vary in depth, since the distance between the dots and their shadows seems to change. But none of these factors are actually changing: the pairs of dots are only moving to a different position on the screen.

Aptly named the Star Trek illusion by researcher Yury Petrov and his team from Northeastern University in Boston, who developed the effect, the trick occurs since our brain perceives the motion as a change in viewing distance. Normally, when you move closer or further away from a scene, colour contrast, depth cues and object size are altered to account for the new viewpoint. So the strong flow in the animation tricks our brain and causes it to infer the new cues it's expecting.

In their recent paper, Petrov and his colleague found that our brain first rescales the size of the dots and then adjusts contrast. Although the depth effect was predicted, it was only observed when they produced the new version of the illusion, shown above, containing shadows.

The illusion has been submitted to this year's Best Visual Illusion of the Year Contest.

Were you able to see all three effects? Let us know in the comments section below.

If you enjoyed this post, check out our previous Friday Illusions, such as a tricky triangle that dupes your brain twice or dizzying silhouettes that seem to change direction.

Source: http://feeds.newscientist.com/c/749/f/10897/s/1d826273/l/0L0Snewscientist0N0Cblogs0Cnstv0C20A120C0A30Cfriday0Eillusion0Estar0Etrek0Eeffect0Ebeams0Etriple0Etrick0Bhtml0DDCMP0FOTC0Erss0Gnsref0Fonline0Enews/story01.htm

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