Unit 3: Sensation and Perception
Our five senses – smell, taste, sight, hearing, and touch – provide us with information about the world. We must convert this information into a form that is usable by the brain, so it can interpret what those sensations mean. The process of collecting information through the sense organs is known as sensation, and the process of making sense of that information is known as perception.
We usually think of sensation as a physiological process, whereas perception is psychological. Since sensation relies on the elements of information that are out in the world, we consider it a bottom-up process. Since perception relies on past experience and knowledge to aid in understanding, we call it a top-down process.
In this unit, we highlight vision and hearing because humans tend to rely most heavily on these senses. Most of the research on sensation and perception has focused on these two senses, so these are the senses we understand the most fully. We will wrap up with the remaining senses, plus a sense that may not seem like a sense – the sense of balance.
Completing this unit should take you approximately 2 hours.
Upon successful completion of this unit, you will be able to:
- compare the concepts of sensation and perception;
- explain the structure and function of the following sensory systems: visual, auditory, olfactory, somatic, gustatory, and vestibular;
- describe how external stimuli are processed in the brain; and
- explain the principles of perception from Gestalt psychology.
3.1: Sensation versus Perception
Our sensory organs (eyes, ears, nose, tongue, and skin receptors) collect information about the world and transfer that information to the brain for processing. In this section, we explore how sensation differs from perception, how absolute thresholds and difference thresholds affect the detection of stimuli, and how our psychological states play a role in perception.
Read this text. Not everything we sense is perceived. Do you think there could ever be a case where something could be perceived without being sensed? Can you think of an example of how a noticeable difference can change as a function of stimulus intensity? Why do you think other species have such different ranges of sensitivity for visual and auditory stimuli compared to humans?
3.2: Waves and Wavelengths
Two of our senses rely on waves as information: sight and hearing. In this section, we develop a better understanding of how the physical properties of light and sound waves affect perception.
Read this text. Why do you think humans are especially sensitive to sounds with frequencies that fall in the middle portion of the audible range?
3.3: Vision
In this section, we study the basic anatomy of the visual system, how the rods and cones function and affect vision, and the role of monocular and binocular cues in perceiving depth.
As you read this text, compare the two theories of color perception. Are they completely different? Color is not a physical property of our environment. What function (if any) do you think color vision serves?
Watch this video, which describes how we process our visual field and how information from the right and left visual field is broken down and sent to the brain.
3.4: Hearing
Now let's discuss hearing – how sound waves are converted to sounds. The basic anatomy and function of the auditory system will be explained, as well as how we encode and perceive pitch and how we localize sound.
Read this text. How does sound localization facilitate survival from an evolutionary perspective? How can we use temporal and place theory to explain our ability to perceive the pitch of sound waves with frequencies up to 4,000 Hz?
Watch this video about the structure of the ear and auditory system. Pay attention to how sound waves are created and perceived and the different functions of the inner and outer ear.
3.5: The Other Senses
There are two chemical senses: taste and smell. That means that both gustation and olfaction rely on receptors in the tongue and nose to connect with appropriate molecules to send sensory information to the brain.
Read this text on the basic functions of the chemical senses, and then move on to the basic functions of touch and balance. Many people experience nausea while traveling in a car, plane, or boat.
How do you explain the function of sensory interaction? How would you respond to someone who says they would do anything not to feel the pain associated with significant injury? Do you think a person's sex influences the way they experience pain? Why do you think this belief is true or false?
Watch this video to learn more about the structures and functions involved in our senses of taste and smell.
3.6: Gestalt Psychology
The subfield of Gestalt psychology is concerned with visual perception. These psychologists concluded that in perception, "the sum is greater than its parts".
Read this text to learn more about Gestalt psychology, especially the figure-ground principle, the Gestalt principles of grouping, and the concept of perceptual set. What does the claim that "the whole is different from the sum of its parts" mean in the context of perception? Look at this figure. How would you influence those who see a duck or a rabbit?
Watch this video on how magicians use the Gestalt concept of good continuation in their acts.
This video shows how all of our senses are subject to illusions and that our perception is most accurate when all of our senses can work together.
Unit 3 Assessment
- Receive a grade
Take this assessment to see how well you understood this unit.
- This assessment does not count towards your grade. It is just for practice!
- You will see the correct answers when you submit your answers. Use this to help you study for the final exam!
- You can take this assessment as many times as you want, whenever you want.