Subjective Contours

Another interesting illusion flew-in directly from Japan! As MindLab originally explains, non-existent contours are sometimes constructed by the brain to compensate for the missing sensory information. Check the four wheels in the second image – the “missing” parts can easily be mistaken as contours of the square, right? See what happens if we fill the missing segments with pink colored lines – the color seems to transparently spread throughout the inside of the contours. In same manner contour of a circle appears, right inside the center of the lines diagram to the right.

However, contours or surfaces don’t appear if we only see the colored segments. Curved line above is made of nothing but short blue lines and demonstrates this perfectly! Now, if we add longer black lines next to each side of blue bar, curved blue band with subjective contours appears! How amazing was that?

18 Replies to “Subjective Contours”

  1. As happens so ofter when viewing this website, I can’t understand the author’s explanation. Vurdlak (the author) should make a better effort to clearly communicate.

  2. While the contour effects in the just black and white items result in stronge illusions of contour for me, the “colour spread” effects are minimal for me. I do not really experience a spread of Pink colour in the coloured square nor does the “blue” of the blue lines “spread” between each blue line for me in either presentation. Sorry.

  3. This is pretty cool.

    What he’s saying is that in the top image, the full square actually looks pink, when it’s not. In fact, there is no square there at all. It’s just the lines of the circles that are pink.

    In the bottom image, it looks like there’s a translucent, but solid, blue line that passes over the black lines. Again, there’s no blue line at all. It’s just the portion of each black line that’s blue.

    (The one on the right looks the same to me in both images.)

  4. For you who do not understand. The contours here are imaginary (illusory) lines that our brain makes up to complete an image. In the left image it appears that there is a grey square, on the right a grey circle. In reality these geometric shapes do not exist. Our brain makes them real by completing incomplete information to construct the geometric image.

  5. The first image has four circles with pink sections. The second image makes the circles disappear and a white square appear.

    The first image has a lot of blue stripes in order of a curvy line.
    The second image makes a ‘solid’ blue line appear in between the black stripes.

  6. They are two completely different(but similar) pictures that have a tiny little thing I call ooooo-aaaaaa-oooooo-aaaaaaa Damn. Please. Save this for crèche.

  7. Very neat illusions. I agree that the explanation leaves something to be desired. I had to read several times and also realized the the left-hand images should be reversed top to bottom with the pink one on the bottom so that it fits better with the one on the right.

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