Ponzo Illusion Collection

So, while waiting for someone to help me fix random illusion hack, and for the Yahoo stuff to update the widget, I decided to share an interesting optical illusion collection with all of you. Previously illusions like this were posted in each separate post, but now as we all got used to them, probably better solution is to group them like this. I got this idea when I visited Dark Roasted Blend.

All of these are variations of the original Ponzo illusion. Previously I thought it’s the same phenomena as Ebinghaus illusion, but there is a slight difference. The Ponzo illusion is an optical illusion that was first demonstrated by the Italian psychologist Mario Ponzo in 1913. He then suggested that the human mind judges an object’s size based on its background. He originally showed this by drawing two identical lines across a pair of converging lines, similar to railway tracks. The upper line looked longer because we interpret the converging sides according to linear perspective as parallel lines receding into the distance – a farther object would have to be longer than a nearer one for both to produce retinal images of the same size. If this collection still wasn’t enough for you, be sure to check Ponzo variation of: soldiers, terrain vehicles, nuns, monoliths, pigglets, spheres, monsters and others .

36 Replies to “Ponzo Illusion Collection”

  1. Seems the mac widget is taking me to google reader to add the comments feed to my reader. It used to bring me right to the page for that days illusion.

  2. Milner and Goodale in 1985 suggested that there is action and perception visual systems. The perception is responsible for what. It is known as the Ventral visual stream using a occipital – temporal pathway. Anyway long story short the ventral system is responsible for object size constancy. So the same sized object perceived in further away seems bigger because we try to maintain an object size constancy notion that would be informative of its dimensions based on size/distance interaction. So the illusion is also in the question. Which object is bigger answer correctly the one further away on realistic terms. Which figure is drawn bigger outside a space continuous doesn’t.

  3. This reminds me of the mistaken belief that the sun has different optical sizes as it rises and sets throughout the day. People I explain this to do not believe that the image of the sun is the same exact size at sunset (when it appears large) as it is at its peak midday (appearing smaller). This is because we are interpreting the sun’s size in refrence to earthbound objects (buildings, trees, etc.) at sunset/rise, but do not have such apparent contrasting objects when the sun is at its peak. THE TEST: hold you hand at arms length (extended) and cover the sun’s image at its peak. Not which of you finger just barely covers it. Then, at sunset, when the sun is “big”, do the same. The same finger will cover the sun!

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