Chapter 1 Overview

Introduction

Click the empty space at left. For about four seconds you will see a picture of a visual scene (Version 1). Four seconds isn’t all that long, but it should be plenty of time for you to get the gist of the scene. Most of you will recognize it as part of New York City’s skyline, with the famous Chrysler and Empire State buildings prominently featured. You will probably also notice the three piers jutting out into the Hudson River in the foreground.

Now click again. The same scene will appear again (Version 2). Or is it the same? In fact, one of the major components of the scene has changed in the second version of the scene. Did you notice the change? Click again to change the scene back and forth a few times and see if you can find it.

Now click here to see the two images toggle back and forth quickly. This will make the change so obvious that you’re probably astounded you didn’t see it before.

As discussed in this chapter of the textbook, your knowledge about the world is limited by what you perceive. This demonstration shows that while our perceptual abilities are incredibly acute in many ways, they are also heavily constrained in others. This leads to the common and popular observation that things are not always what they seem.

Much of this textbook deals with the physiological and psychological systems that allow us to see, hear, feel, smell, and taste the incredible range of stimuli we can perceive. But we will also spend a lot of time exploring the constraints and limits of our perceptual systems, since what we can’t perceive is often just as important (and sometimes even more interesting) as what we can.

We’ll revisit the phenomenon revealed by our small demonstration here, known in the modern perception literature as change blindness, in Chapter 7. The purpose of Chapter 1 is to introduce you to a few concepts we’ll encounter over and over throughout the rest of the book. Some of these concepts are explored in the activities on psychophysics (Activity 1.1), Fourier analysis (Activity 1.2), and neurons (Activity 1.4). Activity 1.3 (Sensory Areas in the Brain) gives a basic map of where information from our various senses first enters the cerebral cortex for advanced processing. For an overview of how scientists and philosophers have thought about the nature of reality for the last 2,500 years, read Essay 1.1 on Senses of Reality through the Ages.

Once you’ve read the chapter in the textbook and done the activities here, use the Study Aids (Study Questions, Flashcards, and Chapter Summary) to review.