Stimulus generalization occurs when a person or animal starts responding to one stimulus, then multiple stimuli, in a similar manner. They have ‘generalized’ their response to stimuli.
For example, a dog may identify a whistle as a stimulus indicating ‘food’. Over time, it may also notice footsteps and tapping a can as stimuli that also signify food.
Stimulus generalization was a concept developed by Ivan Pavlov in his work on classical conditioning. The basic premise is that a reaction to a specific stimulus can be conditioned over time when that stimulus is associated with something else.
Definition of Stimulus Generalization
Stimulus generalization comes from classical conditioning and behaviorism theory. This theory explores how a stimulus can lead to a learned or trained response.
Scholars have shown that stimuli that are similar to the initial stimulus will evoke a response similar to the original stimulus.
For example, Ivan Pavlov conducted experiments on dogs’ salivation. He found that the dog may not only salivate to the sounds of the assistant’s footsteps, but also to similar sounds. Those sounds could include a knock on the door, or lightly tapping two pieces of wood together.
This is called stimulus generalization. The response to the initial stimuli becomes evoked by other stimuli that are similar to the initial one.
Examples of Stimulus Generalization
1. Little Albert
Short Explanation: The Little Albert experiment was an experiment where a child named Albert was taught to fear white fluffy things that look like a rat (such as white beards).
The case of Little Albert may be the most famous example of classical conditioning in history. It was an early experiment by behaviorist John B. Watson and his assistant Rosalie Rayner.
The purpose of the experiment was to demonstrate how phobias are developed. They started with a baby only 9 months old named Albert. The first time they showed Albert a white rat, he had no reaction.
However, the next time they showed the white rat they hit a metal pipe with a hammer to make a very loud noise. This made Albert cry. They did this repeatedly.
After that, every time the baby saw an object that was similar to the white rat, such as a furry white toy or Watson’s white beard, little Albert began to cry. He had developed a fear of objects that looked similar to the white rat. Thus, demonstrating stimulus generalization.
2. The Dog and the Whistle
Short Explanation: A dog may respond to a flute or bell in the same way it has been trained to respond to a whistle.
There are many ways to train a dog to return home when needed. One common way is to use a whistle. Whenever the dog hears the whistle, it knows that it is time to go home. The dog has learned a conditioned response: hear whistle, return home.
However, sounds that are similar to the whistle will also work. For example, if your neighbor’s child plays the flute, which emits a high-pitched sound, then the dog may return home whenever the neighbor practices playing.
This is a case of stimulus generalization. The flute’s sound is similar enough to the original stimulus (whistle) that the dog will exhibit the same conditioned response (i.e., returning home).
Related: Conditioned Stimulus Examples
Short Explanation: A war veteran may feel heightened trauma when exposed to fireworks because they sound and look like explosions experienced in war.
Post-traumatic stress disorder (PTSD) involves having a strong fear or anxiety response after at least one exposure to a very traumatic event. That event is usually a very shocking, scary, or dangerous situation.
The event activates a split-second “fight-or-flight” response in the body. This is the body’s natural response that serves to protect a person from danger.
However, after exposure to that event, the person may experience intense anxiety or fear in situations that are similar. Those reactions can occur long after the initial exposure to the initial trauma-inducing event.
Many stimuli can trigger a response. For example, odors, objects, words, or situations can generate a strong reaction. The more similar the trigger is to the initial event, the more likely that a response will be activated.
4. Parenting, Children, and School
Short Explanation: A parent who teaches their child to say ‘thank you’ at home will transfer that skill to other situations such as when their teacher gives them something in the classroom.
Teaching a child to clean their room is a goal most families strive to attain. The first few times a child cleans their room the parents can give a reward. After repeatedly pairing the reward with cleaning their room, the child will clean their room on their own (in theory).
Stimulus generalization comes into play when the child’s behavior transfers to other, similar places. For example, when the child goes to school, they exhibit the same behavior. Instead of having to relearn the behavior of cleaning up, the behavior is simply generalized to a similar situation.
The same process occurs with other habits, like using table manners at home and in other situations that are similar, such as eating at a friend’s home.
5. Reading Set Defenses in Football
Short Explanation: When a set defensive play is in a formation that has similar characteristics to a known play, a skilled quarterback will be able to identify that play.
In the modern version of American football, the game has become quite complex. The offensive and defensive playbooks can consist of hundreds of pages. Being able to identify an opposing team’s strategy can be a skill that takes considerable time.
Of course, defenses can try to hide their play calling by using a variety of “looks”. With experience however, a quarterback can develop an “instinct” for what the defense will do by quickly examining the placement and movement of the opposing team’s players.
That instinctive analysis is a result of stimulus generalization. Because the defense is in a formation that has similar characteristics to a known play, the quarterback will be able to identify that play.
6. Look-alike Packaging
Short Explanation: When we see packaging that looks similar to our favorite brand, we are more likely to pick it up and buy it due to the branding association.
If you are in a hurry at the supermarket you may reach for the wrong item. Look-alike packaging is a very common marketing trick. It involves designing a package that looks very similar to a well-known product.
There will be similarities in the size and shape of the product. The color scheme and font will also be nearly identical. Unless you look carefully, it can be very difficult to distinguish between the original product and the look-alike one (McCoy, 2005).
This, of course, is done to take advantage of stimulus generalization. The greater the similarity between the two packages, the greater the chances that shoppers will choose the secondary product.
This seems relatively harmless, but not always. In the case of medicine, this can actually lead to treatment errors and dangerous health consequences. It has become a serious concern in the medical profession.
Furthermore, if packaging is designed to intentionally cause product or brand confusion, there is the potential for trademark litigation to occur.
7. Product Line Extension
Short Explanation: Brands expand their product lines carefully, ensuring the new products look and feel like the original products to ensure users retain a sense of familiarity with the products.
Product line extension is when a brand creates other products that are very similar to one that already exists.
For example, for a very long time the Hershey Company offered only one version of Reese’s Peanut Butter Cups. The success of the candy was hard to ignore. So, the company decided to take advantage of that success and develop other versions.
The newer versions are very similar in size, shape, packaging, ingredients, and taste.
With careful consumer testing and analysis, the company can determine when they have strayed too far from the original. If a product is too different, then it will not be successful as stimulus generalization will not occur.
This is a very effective method for large corporations to utilize stimulus generalization to increase profits.
8. Fear Appeals through Image Association
Short Explanation: Fear campaigns attempt to associate scary images with the behavior they want to stop. For example, cigarette packaging attempts to associate cigarettes with images of unhealthy lungs.
The principles of classical conditioning and stimulus generalization are widely used in advertising and marketing. Those principles are also used in health promotion and safety campaigns (Witte, & Allen, 2000).
Before seatbelts were mandatory in most U.S. states, there were several public service campaigns that tried to encourage seatbelt use. The format of the television ads involved pairing images of accidents with images of not wearing a seatbelt.
So, when people went to their car, they would be more likely to put on their seatbelts. Their car and the seatbelt had very similar characteristics to those shown in the ads.
This use of stimulus generalization has also been used in stop-smoking and drinking-and-driving campaigns. Research has demonstrated that feal appeals are somewhat effective at changing behavior.
9. Food Aversions
Short Explanation: People will feel averse to foods that look like other foods they don’t like. For example, a child may not like any foods that are green, regardless of taste.
Developing an aversion to certain kinds of food is a very adaptive behavior. It is beneficial and has helped human beings survive for thousands of years.
For example, suppose a person is walking in a forest, picks up a mushroom, and eats it. A few minutes later they become nauseous. From that point on they may develop a strong aversion to other mushrooms, especially those that look similar.
As Pavlov’s Little Albert experiment demonstrated, a lot of fears can be explained in terms of stimulus generalization. Keep in mind that a stimulus can be an object, an odor, sound, or place. Basically, any sensory modality can be involved.
10. Dinner is Served
Short Explanation: Dogs associate the crinkling of a cereal packet with the crinkling of their dog food packaging.
Some of the best examples of stimulus generalization come from household pets. For example, the sound of dry dog food rattling about in the bag is a key stimulus that predicts dinner time.
Over time your dog has learned that when it hears that sound, dinner is served. Anytime they hear that sound they will surely come trotting to their bowl soon enough.
However, similar sounds will provoke the same behavior. Getting out a box of cereal for yourself can create a similar sound. When your dog hears that sound, it will think it is time for them to eat too.
This is a straightforward example of the sound of one stimulus generalizing to a very similar sound.
Stimulus generalization is a component of classical conditioning that has applications in nearly every aspect of our lives. It can explain how we develop a wide range of preferences and fears.
It can also help us understand how to teach children; how experienced quarterbacks can predict the opposing team’s play; and how some severe psychological traumas develop, such as PTSD.
Stimulus generalization is pervasively used in marketing and advertising. Corporations will spend millions developing look-alike packaging, and can make millions by extending the product line of their best-sellers.
Unfortunately, the use of stimulus generalization can be dangerous. The medical profession has become increasingly concerned about medications that have similar packaging. In a busy hospital setting, reaching for the wrong medicine for a patient can have serious consequences.
National Institute of Mental Health. (n.d.). Post-Traumatic Stress Disorder. https://www.nimh.nih.gov/health/topics/post-traumatic-stress-disorder-ptsd/
McCoy, Linda. (2005). Look-alike, Sound-alike Drugs Review: Include Look-alike Packaging as an Additional Safety Check. Joint Commission journal on quality and patient safety / Joint Commission Resources. 31. 47-53. doi: 10.1016/S1553-7250(05)31007-5.
Watson, J. B., and Rayner, R. (1920). Conditioned emotional reactions. Journal of Experimental Psychology 3(1): 1. doi: http://www.scribd.com/doc/250748771/Watson-and-Raynor-1920
Witte, K., & Allen, M. (2000). A meta-analysis of fear appeals: Implications for effective public health campaigns. Health Education & Behavior, 27(5), 591-615. doi: https://doi.org/10.1177/109019810002700506
Dr. Chris Drew is the founder of the Helpful Professor. He holds a PhD in education and has published over 20 articles in scholarly journals. He is the former editor of the Journal of Learning Development in Higher Education.