Principles of Sensation
Psychologists used a truly scientific lens for one of the first times, when they began to study sensation and perception. In order for people to form thoughts and emotions about the world around them, they need to consider what they can hear, see, taste, and touch, as well as what remains hidden from perception.
Distinguishing Between Sensation and Perception
Sensation is a bottom-up process. This means that your senses receive information like size, shape, or smell, and transmit it to the brain. The brain then makes a decision on how your should behave. For example, your senses will allow you to see a pizza sitting on the table and smell its ingredients. This information will go to your brain, which will tell you to take a bite.
Perception is a top-down process. This means you use general information in your surroundings to make sense of small details. Top-down processing is based on what you have experienced in the past, or what you already believe. For example, if you come to a traffic sign in your car and a couple letters are scratched off of the sign, you can use top-down processing to figure out that since the sign is red, an octagon, and has the letters 's' and 'o' still visible, that it is a stop sign.
Take a moment to view the video, Can You See These Optical Illusions: BrainCraft, from eMediaVASM, to learn more about the differences between sensation and perception. As you watch the video, think about answers to the following questions:
- How do you see the images in the video?
- How does the size of your visual cortex affect perceptions? Why?
- How does culture impact perception?
Transduction
Since the brain is trapped in the skull, and isolated from the rest of the body, it has to go through a process called transduction. In this interactivity, you will discover how transduction works. Click the player to begin.
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Sensory Thresholds
Some stimuli are too faint for you to detect. In this interactivity, you will explore how thresholds allow you to measure the limits of your sensory experience. Click the player to begin.
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Sensory Adaptation
Imagine that you and your family are cooking a fantastic meal of spaghetti. At first, you are keenly aware of the smells of the food: the tomatoes, the basil and other herbs, perhaps even the more subtle smell of olive oil, or the noodles boiling. After eating the meal, you settle down to do some homework for a while, and the smells of the meal seem to fade. Then you go out to run a quick errand. When you come back into the house an hour later…whoosh! The smell of the earlier pasta dinner seems as strong as ever.
Has this ever happened to you? If so, you experienced the concept of sensory adaptation first-hand. Over time, your ability to notice a particular stimulus decreases because sensory systems begin to adapt to it, and take less note of it. While this phenomenon might be particularly notable in the case of smell, sensory adaptation can occur with all of the senses. You are more likely to notice a sudden change in light or sound, which is one reason why frequent changes in light, color, and volume happen when a commercial comes on the television. The advertisers understand how sensory adaptation helps them get your attention.
Signal Detection Theory
Although scientists have determined the types of stimuli humans can detect in relation to absolute and difference thresholds, it is not always easy to predict when a specific person will be able to detect a particular signal. In this interactivity, you will learn reasons why someone may or may not be able to detect certain signals. Click the player to begin.
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Principles of Sensation Review
Now that you have learned about principles of sensation, review your knowledge in this non-graded activity. Click the player to get started.