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The opposite of generalization is discrimination. Discrimination occurs when an organism responds differently to two stimuli. An adult scratched by an angry cat typically would not develop a fear of dogs. A one-year old might! Our knowledge of the world includes sharp distinctions between animals such as cats and dogs. We make discriminations a one-year-old does not yet make.

What is discrimination learning?

In classical conditioning, discrimination occurs when one stimulus triggers a conditional response but another does not. To set up discrimination in the laboratory, a researcher creates a situation in which the two stimuli predict different things. For example, a green light is followed by meat powder, but a red light is not. Soon the dog discriminates between green and red lights. It salivates to the green light but not to the red light.

How can discrimination learning be used to investigate sensory capabilities of an animal?

Discrimination is evidence that an animal notices the difference between two or more stimuli. That makes the technique of discrimination learning very useful. We cannot ask a dog whether it sees in color, but we can easily arrange a discrimination experiment that reveals the answer. Two stimuli are matched in shape and brightness, differing only in color. One is made to predict delivery of food powder. The other never predicts food powder. The positions of the two stimuli are randomized, so the dog cannot tell the stimuli apart by their position, only by their color. If the dog learns to salivate to one light and not the other, then we know it can tell the difference between them. (And, yes, experiments like this show that dogs can see in color.)

How is discrimination learning used to study young babies?

Similarly, in developmental psychology research, very young babies can provide research data through discrimination learning techniques. In one procedure, a baby sucks on a nonnutritive nipple (which is basically a pacifier connected to a computer). If the baby sucks faster when it sees the mother's face rather than a stranger's, this shows the baby can tell them apart. In other words, it can discriminate between them. Such experiments have shown that babies can detect their mother's faces, voices, and odors.

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