Chapter 8 Introduction

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The Psychology of Vision

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CHAPTER OUTLINE

How the Eye Works

  • Functional Organization of the Eye
  • Differences Between Cone Vision and Rod Vision

Seeing Colors

  • The Trichromatic Theory
  • The Opponent-Process Theory

Development and Plasticity of the Visual System

  • Vision at Birth
  • Is “Experience” Necessary to See?

Seeing Forms, Patterns, and Objects

  • The Detection and Integration of Stimulus Features
  • Gestalt Principles of Perceptual Grouping
  • Evidence That Wholes Can Affect the Perception of Parts
  • Recognizing Objects
  • Two Streams of Visual Processing in the Brain

Seeing in Three Dimensions

  • Cues for Depth Perception
  • The Role of Depth Cues in Size Perception

Multisensory Perception: Combining Senses

  • Multisensory Integration
  • Synesthesia

Reflections and Connections

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We are visual creatures. Our eyes are our primary gateway for perceiving and understanding the physical world in which we survive. We say “I see” to mean “I understand,” and when we doubt some claim, we say “I’d have to see it to believe it.” Our visual system provides us with such rich, clear, solid-looking, and generally useful perceptions of the physical world that it is easy for us to forget that the physical world and our sight of it are not one and the same thing.

In reality, our visual perceptions are subjective, psychological experiences, which our brains create almost instantly, and continuously as long as our eyes are open, from clues that lie in the patterns of light reflected off objects. The machinery that underlies our ability to produce such perceptions is incredibly complex. Brain scientists have estimated that somewhere between 25 and 40 percent of the human brain is devoted exclusively or primarily to the analysis of input from the eyes (Gross, 1998; Sereno et al., 1995). It is no wonder that vision is the sense to which psychologists have paid by far the greatest attention.

Vision begins with activity in the eyes, and that is where this chapter begins. From there we go on to examine our abilities to perceive colors, patterns, objects, and depth in three-dimensional space. We conclude the chapter with a discussion of the fascinating phenomenon of multisensory perception.