AP Psychology: Sensation and Perception Notes

Review what you’ve learned about sensation and perception with our AP Psychology notes. These processes are our only way to get information about the outside world. The exact distinction between what is sensation and what is perception is debated by psychologists and philosophers. It’s important to understand both to earn a top score on the AP exam. Get an overview of key AP Psychology key terms and concepts related to sensation and perception.

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AP Psychology Sensation & Perception: Key Takeaways

Review some key sensation and perception concepts you should know for the AP Psychology exam.

1. All our senses work in a similar way. In general, our sensory organs receive stimuli. These messages go through a process called transduction, which means the signals are transformed into neural impulses. These neural impulses travel first to a part of the brain called the thalamus and then on to different cortices of the brain. (The sense of smell is the one exception to this rule).
2. Perception is the process of understanding and interpreting sensations. Psychophysics is the study of the interaction between the sensations we receive and our experience of them. Researchers who study psychophysics try to uncover the rules our minds use to interpret sensations.
3. You can think of sensation in more general terms: the activation of our senses (eyes, ears, and so on) and perception as the process of understanding these sensations.

AP Psychology Sensation & Perception: Key Terms

Review the following key terms related to sensation and perception for the AP exam.

Sensation Terms

• Sensory adaptation: Decreasing responsiveness to stimuli due to constant stimulation.
• Transduction: The term transduction refers to the translation of incoming stimuli into neural signals. This term applies not only to vision but to all our senses. In vision, transduction occurs when light activates the neurons in the retina. There are several layers of cells in the retina.
• Trichromatic theory: Competing theories exist about how and why we see color. The oldest and simplest theory is trichromatic theory. This theory hypothesizes that we have three types of cones in the retina and that each type detects a different primary color of light: blue, red, or green. These cones are activated in different combinations to produce all the colors of the visible spectrum.
• The opponent-process theory: The opponent-process theory states that the sensory receptors arranged in the retina come in pairs: red/green pairs, yellow/blue pairs, and black/white pairs. If one sensor is stimulated, its pair is inhibited from firing.

• Place theory: Place theory holds that the hair cells in the cochlea respond to different frequencies of sound based on where they are located in the cochlea. Some bend in response to high pitches and some to low. We sense pitch because the hair cells move in different places in the cochlea.
• Gate control theory: Gate control theory helps explain how we experience pain the way we do. This theory explains that some pain messages have a higher priority than others. When a higher-priority message is sent to the brain, the gate swings open for it and swings shut for a lower-priority message, which we will not feel.
• Taste receptors: Taste receptors are located on papillae, which are the bumps you can see on your tongue.

Perception Terms

• Top-down processing: When we use top-down processing, we perceive by filling in gaps in what we sense. Top-down processing occurs when you use your background knowledge to fill in gaps in what you perceive.
• Bottom-up processing: Bottom-up processing, also called feature analysis, is the opposite of top-down processing. Instead of using our experience to perceive an object, we use only the features of the object itself to build a complete perception. We start our perception at the bottom with the individual characteristics of the image and put all those characteristics together into our final perception.
• Gestalt psychology: At the beginning of the twentieth century, a group of researchers called the Gestalt psychologists described the principles that govern how we perceive groups of objects. Gestalt psychology points out that we normally perceive images as groups, not as isolated elements.
• Linear perspective: If you have taken a drawing class, you have learned monocular depth cues. Artists use these cues to imply depth in their drawings. One of the most common cues is linear perspective. If you wanted to draw a railroad track that runs away from the viewer off into the distance, most likely you would start by drawing two lines that converge somewhere toward the top of your paper.
• Retinal disparity: Other cues for depth result from our anatomy. We see the world with two eyes set a certain distance apart, and this feature of our anatomy gives us the ability to perceive depth. The finger trick you read about during the discussion of the anatomy of the eye demonstrates the first binocular cue— retinal disparity (also called binocular disparity). Each of our eyes will view an object from a slightly different angle. The brain receives both images. It knows that if the object is far away, the images will be similar, but the closer the object is, the more disparity there will be between the images coming from each eye.

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