Stimulus Input: Attention and Set

Perception is the way that sensory information is chosen and transformed so that it has meaning. Once sensory input starts, an individual uses perceptual processes to select among sensory input stimuli and to organize them so that relevant action can occur. (In the computer analogy, the process of perception would represent use of both hardware and software in the central nervous system; many of the perceptual processes are innate—hardware—but some may be modified—software.)

Attention. Too many events occur simultaneously in the environment to pay attention to all of them at once, so selective attention is used to focus on those stimuli relevant to current activity. (For example, you might not generally pay much attention to wind direction, but you do if you're flying a kite or hitting a golf ball.)

Set. In terms of perception, a set, a predisposition to respond in a particular fashion, may be one of several types.

  • Motor set. When attending to a stimulus, an individual organizes muscular responses, a motor set, to be ready for the particular attention situation. For example, a golfer getting ready to hit a golf ball adopts a particular posture and a practiced way of holding the golf club; similarly, members of basketball teams adopt particular stances, motor sets, as they stand lined up and ready to jump while waiting for the free throw.

  • Perceptual set. A perceptual set is the readiness to interpret a stimulus in a certain way. For example, if you have just run a red traffic light, you might be more inclined to view a flashing light as a police car than as just a bright turn signal. (Note that perceptual sets occur in all of the sensory modalities, not just vision.)

  • Mental set. A mental set is a predisposition to think about a situation or a problem in a specific way. For example, a student's poor performance on a math assignment might be because of lack of preparation or because of the mental set “I just can't do well on math problems.”

Stimulus characteristics that affect set. A variety of stimulus characteristics affect perception and the set that is formed.

  • Stimulus intensity. If other stimulus factors are comparable, a more intense stimulus attracts more attention than does a more subtle one. For example, a loud siren gets more attention than a faint one.

  • Stimulus changes. Stimulus changes elicit more attention than does sameness or monotony. A flashing light, for example, stands out in a horizon of steady city lights.

  • Stimulus magnitude. Stimulus magnitude is also a factor in attracting attention. For example, a large advertising billboard attracts more attention than a small one.

  • Stimulus repetition. A repeated stimulus affects attention; the public quickly recognizes a product seen in repeated advertisements.