Cognitive Psychology: Perceptions and Visual Illusions via Imagination

When looking at a scene or graphic, all humans have the natural and subconscious ability to extrapolate beyond what is visible. In other words, when information is hidden or assumed to be hidden, humans make it up in their minds.

This ability to mentally extrapolate beyond the known is essential to normal living. We regularly make quick guesses with limited information. When you step on a sturdy looking building step, you assume it will hold your weight. When you pull a book from the library shelf, you assume the pages are filled with words. When your waitress brings you a steaming coffee mug, you assume it is filled with a hot liquid.

In many cases this extrapolation is accurate, or at least a fair estimate of reality. If your dog is standing on the other side of the open doorway, half hidden by the wall, you correctly assume that an entire dog exists. As the dog steps foreword into the room, your assumption is proven correct. When the waitress puts down your steaming coffee mug, you are far from surprised to see it’s filled with the hot coffee you ordered. Humans would be a dim species if we couldn’t make these kinds elemental deductions.

In many cases, however, the extrapolations are wrong. Though we perceive them to be real, the are nothing more than make believe. Many of these bogus extrapolations involving the viewer subconsciously seeing what he wants to see or expects to see. Sometimes these errors in thought are corrected (“Oh, the cup is filled with tea, not the coffee I asked for”). Often times the error in extrapolation is never corrected, and the misperception exists throughout the person’s life.

The following are examples of correct and incorrect perceptions based on extrapolating beyond what is seen.


Though the dogs block the view, we assume there is snow behind them like the snow we see surrounding them.


Though the overlapping prevents us from knowing, most will assume the above picture shows whole playing cards. I assume the cards are rectangular and whole.


The below says “I Love You” multiple times:

Now read the same printed text below with the ruler removed:



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In the above, most perceive a cube behind the three diagonal bands

With the bands removed, we perceive something different.


Many perceive a white triangle here, even though there isn’t one.


Is it three bars or a horse shoe?

With this visual illusion, the viewer forms a perception about the whole from looking at just one end. When she looks at the rest of the graphic she realizes her extrapolation, or initial perception of the whole, was wrong. Unlike the other pictures in this chapter, there is no missing information. All of the information is there for the eyes to see, but the viewer forms her perception as if information is hidden.

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