Private Nature of Perceptual Experience

What Does Labeling Experience Indicate about Experience?

What does it mean if two people say “The apple looks red,” or, using another descriptive technique, “It is the same color as blood”? Does this provide any information about what the people are experiencing? To a certain extent it does. Their description indicates that they label what they are experiencing as “red,” and that their color-experience caused by the apple is similar to their color-experience caused by blood. But labeling or com paring to another experience does not capture the true essence of experience. The essence of our experience—what it is like to experience red, feel a pinprick, or hear the sound of a violin—is called qualia. The experience of red, looked at in this way, can be described as having a red quale. Thus, our question becomes, “Is one person's red quale the same as another person's red quale?” It is clear that their response of “red” to the apple is no more than a label for each person's “red-quale” experience. It could be that one person's red quale is a different shade of red or perhaps a completely different color altogether, compared to the other person's red-quale.

The idea that two people's qualia might be different may appear counterintuitive because of “shared experiences,” such as one person saying “the sky is a beautiful shade of blue” and another person agreeing. Although this agreement may imply a shared experience of “blueness” or “beauty,” there are a number of reasons why it is reasonable to expect that different people could experience the same stimuli differently. This conclusion derives from both physiological and behavioral considerations.

Physiological Reasons to Expect Differences in Perception

There are many examples, which extend across senses, of situations in which physiological differences between people might cause differences in perception. The basic idea is that just as there are physiological differences between people's appearance, physical strength, and susceptibility to certain genetically based conditions, there are also physiological differences in the mechanisms responsible for perception.