Chapter 87. Biologically Adaptive Associations

Learning Objectives

associative learning

learning by forming a link between two events

learning

changing your behavior or your knowledge as a result of experience

biological preparedness

some learned associations between stimuli have survival value, and thus can be conditioned more easily than others

neutral stimulus (NS)

in classical conditioning, an event that produces no response (is ignored)

classical conditioning

a simple form of learning that involves forming an association between two stimuli

stimulus

an external event, such as a light or sound, detected by our senses

conditioned response (CR)

in classical conditioning, a response that, after conditioning, is triggered by a formerly neutral stimulus

taste aversion

classically conditioned fear and avoidance of a particular flavor

conditioned stimulus (CS)

in classical conditioning, an initially neutral stimulus that, after conditioning, is able to trigger a response

unconditioned response (UR)

in classical conditioning, a response that is automatically triggered by a stimulus event

experiment

a method of research that manipulates an independent variable to measure its effect on a dependent variable

unconditioned stimulus (US)

in classical conditioning, an event that automatically triggers a response; no learning is required

taste aversion

classically conditioned fear and avoidance of a particular flavor

Biologically Adaptive Associations

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Learning Objective:

Describe Garcia’s research on biological preparedness in classical conditioning.

Review

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1. Classical conditioning is a form of associative learning in which two stimulus events that repeatedly occur close together in time eventually become associated with one another.

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The figures show how a dog responds before conditioning, during conditioning, and after conditioning Before conditioning: Dog food is the US (the unconditioned stimulus) that produces a salivation response (the UR or unconditioned response). The dog salivates when food is presented. When a can opener (the NS or neutral stimulus) is presented, the dog has no response. The dog does nothing when it hears a can opener. During conditioning: A can opener (the NS) is heard and then dog food is presented (the US). This produces a salivation response (the UR). The dog salivates after the can opener and food are presented. After conditioning: A can opener is heard (now the CS or conditioned stimulus), which produces a salivation response (the CR or conditioned response). The dog now salivates when the can opener is heard.

2. For example, if a dog salivates (an unconditioned response, or UR) every time its tongue touches dog food (an unconditioned stimulus, or US), then repeated exposure to the sound of a can opener (a neutral stimulus, or NS) just before the food appears will produce an association between the can opener sound and the food. The can opener sound becomes a conditioned stimulus (CS) that is capable of producing saliva, now called a conditioned response (CR), even if no food arrives.

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The image is a line graph with two lines. The X axis is labeled “Number of conditioning trials” and ranges from 1 to 10 in increments of 1. The Y axis is labeled “Strength of the association” and ranges from Low to High. The first line in the graph represents “not biologically prepared”. This line curves from low strength at 1 trial to medium strength at 10 trials. The curve is steady, peaking at around 7 trials and staying consistent over the remaining trials at medium strength. The second line in the graph represents “biologically prepared association”. This line curves from just below medium strength at 1 trial to high strength at 10 trials. The shape of the curve is similar to the one for not biologically prepared, curving steading until peaking at 7 trials and staying consistent over the remaining trials at high strength.

3. Early researchers, including Ivan Pavlov and John Watson, believed that any unconditioned stimulus (US) could easily become associated with any neutral stimulus (NS). Against this view, in the 1960s, John Garcia demonstrated biological preparedness—the idea that certain associations are learned more easily because they have survival value for an animal.

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Photograph by Kris Yinqing Liu/Getty Images

4. For example, Garcia found that if rats eat a new type of food and later become sick, they will easily learn the association and will avoid the taste of that food in the future. But they won’t learn to avoid the sights and sounds of the location in which they ate the food.

Practice: Biological Preparedness

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Practice: Biological Preparedness

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We’ll try to demonstrate the concept of biological preparedness by simulating an experiment in Garcia’s lab. The researchers put thirsty rats, one at a time, in a chamber that had a container of water sweetened with saccharine, an artificial sweetener. As the rat was drinking, the movement of the drinking spout turned on a flashing light and a clicking noise. Using the terminology of classical conditioning, each of those three events (the taste of the water, the noise, and the light) was initially a(n) ________.

Illustration: a single rat in the chamber with container of water on wall with label “Saccharin water”, light bulb with label “Flashing light”, audio speaker with label “Clicking noise”, electric grid on floor, and x-ray generator box on side wall.

The sweet taste of the water, the light, and the noise were initially neutral stimuli (NS), because the rat had not yet formed any associations to those stimuli. Now, select the CONTINUE THE EXPERIMENT button.

The rats in this experiment were divided into two groups, and each group received a different type of unconditioned stimulus (US).

Illustration: a single rat in the chamber, drinking from the water bottle while the sound and light are turned on, with labels for “Water bottle” “Light” and “Sound”

While the three neutral stimuli (NS) were present, the rats in the “shock” group each received an electric shock (US) to their paws, causing immediate pain and fear (UR).

While the three neutral stimuli (NS) were present, the rats in the “radiation” group each received a dose of x-ray radiation (US), which caused the rats to become nauseated (UR) within an hour or so.

Both groups received the same neutral stimuli (NS), but different unconditioned stimuli (US). According to the basic principles of classical conditioning, all three of the neutral stimuli should have become conditioned stimuli (CS) for both groups of rats, leading all the rats to fear and avoid the taste of saccharin, the flashing light, and the clicking noise. But that didn’t happen. Can you predict what each group of rats actually learned to fear? Press the CONTINUE THE EXPERIMENT button to see the results.

Contrary to expectations, the rats developed selective associations which differed for the two groups. Rats in the “shock” group developed a strong fear of the light and the sound, but did not fear the sweetened water. Rats in the “radiation” group did not fear the light or the sound, but instead developed a strong fear of the sweetened water, and avoided any food that had a saccharin taste.

These results demonstrated biological preparedness in associative learning. If a rat eats or drinks something with an unusual taste, and then becomes ill, it easily forms an association between those events. Rats that don’t quickly form these taste aversions are more likely to die before reproducing.

On the other hand, it is difficult for a rat to form an association between a light or noise and getting sick later. In the real world, sudden lights and noises are more likely to accompany immediate pain. Rats seem biologically prepared to associate the light and sound with the painful shock.

Illustration: Composite illustration showing both chambers; on left, rat is being shocked, with label above chamber “Shock group”; on right, rat is receiving radiation, with label above chamber “Radiation group”

Quiz 1

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Quiz 1

Match the terms with their descriptions by dragging each colored circle to the appropriate gray circle. When all the circles have been placed, select the CHECK ANSWER button.

Perhaps you should back to review research on biological preparedness in classical conditioning.

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conditioned response (CR)

neutral stimulus (NS)

biological preparedness

taste aversion

conditioned stimulus (CS)

unconditioned stimulus (US)

unconditioned response (UR)

some learned associations between stimuli have survival value, and thus can be conditioned more easily than others

a response that, after conditioning, is triggered by a formerly neutral stimulus

an initially neutral stimulus that, after conditioning, is able to trigger a response

an event that produces no response (is ignored)

classically conditioned fear and avoidance of a particular flavor

a response that is automatically triggered by a stimulus event

an event that automatically triggers a response; no learning is required

Quiz 2

dnd_test

Quiz 2

Drag the most likely outcome to the gray rectangle above each experiment condition. When the outcomes have been placed, select the CHECK ANSWER button.

While these two rats were being exposed to the same three stimuli (flashing light, buzzing sound, saccharin taste), one received radiation and the other received a shock. Based on Garcia’s research, what is the likely outcome of this experiment?

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Perhaps you should back to review research on biological preparedness in classical conditioning.

OUTCOME:

Rat learns to fear and avoid the saccharin taste.

Rat does not learn any associations.

Rat learns to fear and avoid the light and sound.

Conclusion

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