Things Are Not As They Seem: What Is A Perception?


What Do We Pick Up?

In a famous experiment, subjects are told to carefully observe a staged event. Then a man in a gorilla suit walks across the stage, bows, and walks off. Almost no one notices it, because they are focusing on something else and not expecting it. A more recent version of this experiment involves radiologists reading MRI film, who do not see a large gorilla imprinted in the film. No one expects a gorilla to be in an MRI. Other experiments also show that we see only what we are prepared to see.

Unconscious Mind

How the unconscious affects perception is unclear. A recent study shows that when typing, the conscious mind really does not know what the fingers are doing. This skill operates through unconscious motor memory.

Another study shows that when observing patterns with hidden objects in them, even though people do not consciously see some of the shapes, the brain processes the meaning of these objects. So, even though the brain decides what we will perceive from the huge amount of possible data, more information is taken in than becomes conscious. Is it our expectations that determine what will be conscious?

Multisensory Brain

The multimodal nature of the brain affects perception. In the past, it was believed that single senses are perceived in specific regions of the brain. Recently, it has been shown that 50 percent of neurons have multisensory connections.

These multisensory circuits influence many ordinary functions. An example is the importance of visual observation of the lips during speech. In experiments, when the visual input is different from the auditory, the visual takes precedence. In fact, a recent study of rating the quality of musical performance shows that even experts rate a performance more by how it visually comes across than the actual sound when both are available. Ears, eyes, and skin all pick up speech; Helen Keller interpreted speech by placing fingers on lips, cheek, and neck.

Another strange perceptual effect includes taste being altered by different sounds, smells, and pictures — an orange drink will taste cherry if colored red. Yet another is the sensation of a desk rising, if one is watching a waterfall with hands on the desk.

Perceptions Determined By Expectation

If expectations are largely responsible for determining perception, what determines our expectations? They are influenced by necessities, desires, medical conditions, pain, and memories. Recent evidence shows that just as perceptions have a high tendency to be faulty, so do memories.

We tend to “see” what is new in a scene, not what has been there before. Our previous experiences tell us what to expect from the new data constantly arriving, and we look for this in the data that have changed. If we first imagine a scene and then look at it, our perception of the scene will be altered by our imagination. In the same way, previous emotional experiences alter what we see. Our perceptions are prioritized by emotions, meaning, personality, and culture.

What we perceive as reality is the brain creating a panoramic scene with smells and a soundtrack. It pieces together millions of bits of information from narrow ranges of light and sound waves and, with the help of the mind, makes it into a coherent scene or story line. In reality, the brain is just responding to electrical signals. It never really sees or hears anything. It makes us believe that we are observing what is really out there and that everyone else is seeing the same thing. In fact, we can only be sure by asking others.

Dr. Jon Lieff graduated from Yale College with a B.A. in mathematics and Harvard Medical School with an M.D. He is a practicing psychiatrist with specialties in the interface of psychiatry, neurology, and medicine.

This article was first published in Brain World Magazine’s Spring 2014 issue.

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