Understanding Stimulus Discrimination in Psychology

Key Takeaways

• Stimulus discrimination is the ability to respond to a specific stimulus while ignoring similar ones, and it occurs in both classical and operant conditioning.
• In classical conditioning, stimulus discrimination happens when a subject learns to respond only to a conditioned stimulus and not to similar stimuli.
• In operant conditioning, stimulus discrimination involves recognizing which behaviors are appropriate in specific situations or in response to specific commands.

Stimulus discrimination is the ability to distinguish one stimulus from similar stimuli. In classical and operant conditioning, it means responding only to certain stimuli and not to similar ones. This is important in learning, as it enables an organism to respond when the appropriate stimulus is presented.

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Key Concepts

In order to understand how it works, there are a few important key concepts to know:

• Discriminative stimulus: This is the specific cue that signals that a behavior is going to be reinforced.
• Stimulus generalization: This means that the subject responds in the same way to a stimulus that is similar to the discriminative stimulus.
• Discrimination training: This is the process of reinforcing only the discriminative stimulus and not reinforcing other stimuli that might be similar. Such training can take place in both classical conditioning and operant conditioning.
• Stimulus control: This refers to the extent to which behavior is affected by various stimulus conditions. Discrimination training is used to create stimulus control so that the subject responds to the right cues.

Stimulus Discrimination in Classical Conditioning

Classical conditioning is a form of learning in which associations are formed between two stimuli. In this process, discrimination is the ability to differentiate between a conditioned stimulus and other stimuli that have not been paired with an unconditioned stimulus.

For example, if a bell tone were the conditioned stimulus, discrimination would involve distinguishing the bell tone from similar sounds.

How Classical Conditioning Works

Classical conditioning works like this:

• Forming an association: A previously neutral stimulus, such as a sound, is paired with an unconditioned stimulus (UCS). The unconditioned stimulus is a stimulus that naturally and automatically elicits a response. For example, the smell of food is an unconditioned stimulus, whereas salivating in response to it is an unconditioned response.
• Responding to a conditioned stimulus: After an association has been formed between the previously neutral stimulus, now known as the conditioned stimulus (CS), and the unconditioned response, the CS can evoke the same response, now known as the conditioned response, even when the UCS is not present.

In Ivan Pavlov’s classic experiments, the sound of a tone (a neutral stimulus that became a conditioned stimulus) was repeatedly paired with the presentation of food (an unconditioned stimulus), which naturally and automatically elicited a salivary response (an unconditioned response).

Eventually, the dogs would salivate in response to the tone alone (a conditioned response to a conditioned stimulus).

What Stimulus Discrimination Looks Like in Classical Conditioning

Now, imagine that Pavlov introduced a different sound to the experiment. Instead of presenting the tone’s sound, let us imagine that he sounded a trumpet. What would happen?

If the dogs did not drool in response to the trumpet sound, it indicated that they could discriminate between the tone and a similar stimulus. Not just any noise will produce a conditioned response. Because of stimulus discrimination, only a very specific sound will elicit a conditioned response.

In classical conditioning, stimulus discrimination helps learners respond to a specific stimulus and not to other similar stimuli.

Stimulus Discrimination in Operant Conditioning

Operant conditioning is a form of learning that relies on rewards and punishments to teach new behaviors.

In operant conditioning, stimulus discrimination refers to responding only to the discriminative stimulus and not to similar stimuli.

For example, imagine that you have trained your dog to jump in the air whenever you say the command, “Jump!” In this instance, discrimination refers to your dog’s ability to distinguish between the command for jumping and similar commands such as sit, stay, or speak.

Another example might be the type of behaviors that are appropriate in one situation but not in another. Because of stimulus discrimination, you recognize that eating with your hands with your elbows on the table might be appropriate in a casual, fast-food restaurant, but that such behavior would be considered inappropriate in a more formal dining setting.

Real-World Examples

Stimulus discrimination also occurs in real life outside of experimental lab settings:

• Only ordering a dish at one restaurant because you know that other restaurants don’t offer that same menu item is an example of stimulus discrimination.
• Your cat being able to tell the difference between hearing you open a bag of chips and you opening a bag of cat treats is another example.
• Marketers rely on stimulus discrimination to help consumers recognize products as distinct from similar products. For example, the packaging on a certain brand of snack cookies might help buyers discriminate between multiple similar products.

In a well-known experiment on classical conditioning, researchers paired the taste of meat (unconditioned stimulus) with the sight of a circle (conditioned stimulus), and dogs learned to salivate in response to the circle. The researchers found, however, that the dogs would also salivate when they saw an ellipse, an oval shape.

Over time, as the dogs underwent more trials in which they did not receive meat when presented with the ellipse, they eventually learned to discriminate between the two similar stimuli. They would salivate in response to the circle, but not when they saw the ellipse.

Stimulus Discrimination vs. Stimulus Generalization

Stimulus discrimination can be contrasted with a similar phenomenon known as stimulus generalization. In classical conditioning, for example, stimulus generalization would involve being unable to distinguish between the conditioned stimulus and other similar stimuli.

In the famous Little Albert experiment, a young boy was conditioned to fear a white rat, but he displayed the fear response upon the presentation of similar white, furry objects.

An example of stimulus discrimination would have been if the little boy in the experiment had distinguished between the white rat and other white, furry objects.

Is Stimulus Discrimination Training Effective?

Stimulus discrimination training is a strategy that can be useful for teaching people to engage in behavior only in the presence of a certain stimulus:

• This may be helpful for teaching people to only respond with specific behaviors in certain settings or situations.
• It may also be helpful for minimizing anxiety and fear responses by reducing the generalization of the fear response.

Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

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By Kendra Cherry, MSEd

Kendra Cherry, MS, is a psychosocial rehabilitation specialist, psychology educator, and author of the “Everything Psychology Book.”

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