AP Psychology

Unit 4: Sensation and Perception

Everything that organisms know about the world is first encountered when stimuli in the environment activate sensory organs, initiating awareness of the external world. Perception involves the interpretation of the sensory inputs as a cognitive process.
AP students in psychology should be able to do the following:


"I have perfect vision," explains my colleague, Heather Sellers, an acclaimed writer and teacher. Her vision may be fine, but there is a problem with her perception. She cannot recognize faces.

In her memoir, You Don't Look Like Anyone I Know, Sellers (2010) tells of awkward moments resulting from her lifelong prosopagnosia - face blindness.

In college, on a date at the Spaghetti Station, I returned from the bathroom and plunked myself down in the wrong booth, facing the wrong man. I remained unaware he was not my date even as my date (a stranger to me) accosted Wrong Booth Guy, and then stormed out of the Station. I can't distinguish actors in movies and on television. I do not recognize myself in photos or videos. I can't recognize my stepsons in the soccer pick - up line; I failed to determine which husband was mine at a party, in the mall, at the market.

Her inability to recognize faces means that people sometimes perceive her as snobby or aloof. "Why did you walk past me?" a neighbor might later ask. Similar to those of us with hearing loss who fake hearing during trite social conversation, Sellers sometimes fakes recognition. She often smiles at people she passes, in case she knows them. Or she pretends to know the person with whom she is talking. (To avoid the stress associated with such perception failures, people with serious hearing loss or with prosopagnosia often shy away from busy social situations.) But there is an upside: When encountering someone who previously irritated her, she typically won't feel ill will, because she doesn't recognize the person.

Unlike Sellers, most of us have (as Module 18 explains) a functioning area on the underside of our brain's right hemisphere that helps us recognize a familiar human face as soon as we detect it - in only one - seventh of a second Gacques & Rossion, 2006). This ability illustrates a broader principle. Nature's sensory gifts enable each animal to obtain essential information. Some examples:

In this unit, we'll look more closely at what psychologists have learned about how we sense and perceive the world around us.

 16Basic Principles of Sensation and Perception
 17Influences on Perception
 19Visual Organization and Interpretation
 21The Other Senses

Powerpoint - "New" Chapter Slides
Powerpoint - "Old"Chapter Slides (just perception)
Powerpoint - Definitions
Study Guide 4 (and Answers 4)
Textbook (sort of an "e-book")