Lecture: Sensation and Perception
Reading Assignment 10:
Perception (pp. 134-151)
Click for objectives for Reading Assignment 10

The tenth reading assignment introduces students to Perception, Percepts, and the two major subcategories relevant to the study of Perception. In the last reading assignment, it was explained that Perception is the cognitive influence or component of what we biologically experience in response to stimulation (i.e., Sensation).

The basic building block of Perception is referred to as a Percept. Percepts are defined as the smallest meaningful units that theorists perceive when looking at a person, place, or thing. For example, in the picture below, many people will see a man or a man running. For most people, that is the smallest meaningful unit that people perceive when looking at the image. However, an artist is likely to see this same image as the series of shapes that can be seen to make up the running man. As a matter of fact, an artist might even perceive the second image in the same exact way. Psychologists believe that Percepts play a very important role in how we perceive our environment; however, there is a debate as to how they play a role.
ra10-running man sketch.jpg

The debate essentially boils down to the importance that we place on cognition and Percepts. In this discussion, cognition refers to the influence that a persons expectations, memory, and emotions have on what a person ultimately perceive. Bottom-Up Processing holds that Percepts are more important than cognition. In summary, what a person observes (i.e., the Percepts) is sent to the brain, and that unique assortment of images influences how you perceive the environment. The cognition of the viewer only has a minimal role in putting together what the brain receives. The other theory, Top-Down Processing, holds that cognition is more important that Percepts. In summary, what a person believes to be true has a greater influence on what a person perceives than what is actually present (i.e., Percepts). The Percept only has a minimal role in putting together what the brain perceives.

The two major subcategories relevant to the study of Perception are Perceptual Organization and Perceptual Interpretation. The first subcategory, Perceptual Organization, is somewhat consistent with the notion of Bottom-Up Processing.

There are four types of Perceptual Organization that will be discussed throughout this reading assignment. First, we will discuss Form Perception. The greatest contributions to the study of Form Perception comes from Gestalt Psychologist who established in the late 1800’s, what is commonly known today as the Gestalt Principles. The Gestalt Principles is a concept that is relevant to not only psychology but to the social sciences, art, and humanities. A phrase that embodies what the Gestalt Principles represents is the following: A whole is other (or often greater) than the sum of its parts (wikipedia.org/Gestalt_psychology). There are 6 types of Form Perception that are discussed in this reading assignment; each of which explains their own unique role in how humans perceive forms when viewing stimuli in their environment. They are as follows: Figure-Ground, Closure, Good-Continuation, Similarity, Proximity, and Simplicity (or Good Figure). Each of these different types of Form Perception can help explain how we identify forms in our environment, by using these basic principles. These basic principles, however, do not always lead us to accurate perception of our environment. Sometimes they might lead to a Perceptual Illusion. A Perceptual Illusion occurs when we misperceive the existence of forms due to these principles leading us to inaccurate perceptions.

The four types of Perceptual Organization are as follows: Form Perception (discussed in detail above), Depth Perception, Motion Perception, and Perceptual Constancy. Second, we will discuss Depth Perception. There are two types of cues that play a role in Depth Perception as well Motion Parallax. Monocular Cues are characteristics that can be seen with one eye, and provides the viewer with information about depth. In contrast, Binocular Cues must be perceived with two eyes and is the byproduct two distinct images from slightly different vantage points (i.e., our eyes). The different vantage points create a three-dimensional environment that contains rich depth information. The concept of Motion Parallax helps us organize perceptual information to identify depth. Motion Parallax has been utilized in video games to relay depth and can be seen almost anytime from within a vehicle moving at high speeds that permits a distant view. Third, is Motion Perception. Evidence suggests that our visual system has become highly adaptive to the perception of motion. Neurons exist in our visual system. These neurons are highly specialized to move in specific directions; collectively, these neurons aid us in our perception of motion as it occurs in our environment.

Lastly, we will discuss the three types of Perceptual Constancy they are named as follows: Size Constancy, Shape Constancy, and Color Constancy. A childhood memory applicable to the concept of Size Constancy comes in the form of an episode of The Kids In The Hall. This HBO comedy series depicted a reoccurring and seemingly deranged character that would pretend to crush the heads of people that he observed with his fingers. The camera does a great job of relaying how this character ignored this aspect of Perceptual Constancy and behaved as if peoples’ heads, from afar, could be crushed with one’s fingers. One of the clips can be seen here, while a more realistic portrayal of reality is likely portrayed in this clip. In a similar manner, the shape and color of objects also remain relatively constant even when we observe them under different circumstances.

The second major subcategory relevant to the study of Perception is Perceptual Interpretation. This subcategory, Perceptual Interpretation, is somewhat consistent with the notion of Top-Down Processing as it highlights how perception is influenced and potentially biased by factors other than the stimulus being viewed. It can explain how when a person is feeling good about themselves their own reflection can be perceived as a very attractive person. That same person, when in a bad mood, could then perceive their reflection as an unattractive person. There is much more than what we look at that influences what we see each day in our environment; understanding these factors has been the goal of many psychologists that investigate Sensation and Perception.



Lefton, L.A. & Brannon, L. (2003). Psychology (8th Ed.). Allyn & Bacon: Pearson Education, Inc.

Draft of Summary
McCrae, T. (2012, Fall). Assignment 2.3. Draft of summary submitted in partial fulfillment of Introduction to Experimental (RPS 410).

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