Critical Thinking Exercise

Perceptual/Optical Illusions

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You must read each slide, and complete any questions on the slide, in sequence.
Critical Thinking Exercise
Perceptual/Optical Illusions

Have you ever experienced a situation in which you were sitting or lying in a dark room and you suddenly “see” an object that is no longer there when you turn on the light? Can the human brain be tricked into seeing something that is not actually there? The simple answer is yes. Sensation is universal and is what our eyes see based on the available stimuli, but perception is little more complex and individualized as it changes based on experience and is what our brain sees and interprets. By arranging a series of colors, images, or patterns strategically, or modifying the way an object is lit, the brain can be tricked into seeing things that do not exist. These tricks are often referred to as perceptual, or optical, illusions.

Visit one of the following Websites: http://www.brainbashers.com/opticalillusions.asp or http://www.moillusions.com/category/optical-illusion-tests/, and select three optical illusions.

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Describe each of your selected optical illusions. How did the illusion trick your brain into seeing something that was not there? For example, did the artist modify the colors, sizes, or patterns?
Your answer has been provisionally accepted. You'll get full credit for now, but your instructor may update your grade later after evaluating it.

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Review your textbook discussion of bottom-up processing and top-down processing (Chapter 3, page 102). Which type of processing did you likely use when looking at the optical illusions? Explain.
Your answer has been provisionally accepted. You'll get full credit for now, but your instructor may update your grade later after evaluating it.

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Watch this short TED-Ed video at http://ed.ted.com/lessons/how-optical-illusions-trick-your-brain-nathan-s-jacobs. The video is about how optical illusions trick your brain into seeing things that do not exist. Why have our brains evolved to see the edges of objects, rather than focusing on the insides of objects?
Your answer has been provisionally accepted. You'll get full credit for now, but your instructor may update your grade later after evaluating it.

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In the TED-Ed video, you are presented with a visual illusion of an upside-down Abraham Lincoln face. According to the narrator, faces trigger activity in which parts of our brain?
Your answer has been provisionally accepted. You'll get full credit for now, but your instructor may update your grade later after evaluating it.

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According to the TED-Ed video, when we scan faces for information, we tend to focus on the

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processing, also called data-driven processing, involves detecting basic features of a stimulus in an effort to recognize a whole pattern.

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When processing visual imagery by analyzing the relationship of the whole to the parts, we are using

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As Kira is looking up at the clouds, she notices that one of the clouds looks like a human face. According to your textbook, why are people especially prone to seeing faces in ambiguous stimuli, such as clouds, food, and shadows?
Suggested Answer: The brains of primates are wired to be uniquely responsive to faces or stimuli that have face-like qualities. This specialized face-recognition system helps us to identify an individual face out of the thousands that we can recognize. However, this ability also leads to false-positives. That is, vague or ambiguous images with face-like features can trigger the brain's face-recognition system, leading us to see faces where they do not exist at all, except in our own mind.