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Human Classical Conditioning
By: Courtney Breyer, Greg Gianopoulos, Erik Money, Nora Uhrich, Nicole Valencia
Organisms make associations between a specific stimulus and a response in single-stimulus
learning events. An example of a single-stimulus learning event is a student learning to associate a time
on a clock (stimulus) with his action of leaving a classroom (response). Single-stimulus learning events
are taken a step further when organisms associate two stimuli together. For example, a professor might
learn to associate a time on a clock (stimulus 1) with the occurrence of students packing up to leave class
(stimulus 2), also learning to associate one or both of the stimuli with her action of leaving the classroom
(response). The professor might not need to see the clock to understand that it is time for her to leave the
classroom, because she has associated the time on the clock (stimulus 1) with the occurrence of students
packing up to leave class (stimulus 2). This example demonstrates associative learning, a phenomenon in
which multiple stimuli are related to each other as well as a response. There are many different types of
associative learning. This lab report focuses on one of these types of associative learning—classical
conditioning.
Classical conditioning is often traced back to the story of Ivan Pavlov and his salivating dogs. In
this story, Pavlov trained his dogs to salivate to the sound of a bell by presenting the sound at the same
time as meat powder, which he noticed to naturally elicit salivation in his dogs. In this way, classical
conditioning allows an organism to learn a conditioned response (e.g. salivation) to a conditioned
stimulus (e.g. the sound of a bell), even though that stimulus may not naturally cause that response
(unlike would an unconditioned stimulus such as meat powder). Much like dogs, classical conditioning
also occurs in humans.
This experiment explored whether a conditioned response (CR) could be created in response to a
verbalized word. The unconditioned stimulus (US) was a squirt of water to a squirtee’s goggles and the
unconditioned response (UR) included blinking, flinching, and smiling. Lastly, the conditioned stimulus
(CS) was the word “BED”.
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Method
Participants
This experiment was performed with a group of five students of Conditioning and Learning
(Psych 236). There was one reader, one squirter, one squirtee, and two observers.
Materials
1 squirt gun
1 instruction sheet
2 word sheets
Procedure
To ensure the squirtee would not prematurely learn the purpose of the experiment, the squirtee
was sent into the hall while the other team members received directions and necessary sheets. Next, the
squirtee was retrieved and given goggles, then seated in a chair facing the squirter, who stood holding the
squirt gun aimed at the squirtee’s goggles. The reader stood behind the squirtee, completely out of the
squirtee’s view, and the observers sat facing the squirtee for a clear view of the squirtee’s behavior.
In an even tone, the reader read aloud a series of words at a rate of one every 2 seconds, nodding
vigorously when the word “BED” (capitalized) occurred. This nod signaled the squirter to squirt the
squirtee’s goggles while the observers recorded squirtee behavior on their corresponding word sheets.
Sometimes the word “bed” (lowercase) occurred, to which no squirt was administered. Observers noted
the squirtee’s reaction to this on the word sheets as well.
Results
The squirtee reacted with face flinches, blinks, and/or laughing when the word “BED” was paired
with a water squirt. When the word “bed” was not reinforced with a squirt, the squirtee still displayed face
flinches and blinks for two trials. The squirtee seemed confused and displayed this through a furrowed
brow, wide eyes, tense face, or smile. After the third “bed” trial, the squirtee did not respond. The squirtee
had similar responses to “BED” when it was reintroduced halfway through the experiment.
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Discussion
The results show that learning occurred because the squirtee continued to flinch or blink even
when the word “bed” was not reinforced with a squirt of water to the eye. Since there was only one
subject, this experiment conformed to a within-subjects design; thus, learning could be inferred by (a)
observing the squirtee’s flinches and blinks and (b) assuming that the squirtee would not flinch or blink if
the word “BED” was not paired with the squirts over trials. In addition, alternative explanations for the
CR are taken into account. For instance, stimulus change is an unacceptable explanation because the US
remained the same throughout the experiment. Likewise, evolution and maturation aren’t acceptable
explanations because the experiment took place over a short period of time with a single participant.
A trial was completed each time a squirt was administered. It took at most 25 trials for the subject
to learn the association between “BED” and a squirt. In order to know if the squirtee’s response was due
to the squirt of water or to the word “BED,” the experimenters used a CS alone test by using the word
“bed” without capitalization. The experiment demonstrates classical conditioning because an US was
paired with a CS to produce a CR. In the experiment the US was water to the squirtee’s eye. The UR was
the squirtee blinking/flinching, smiling, and/or jumping. The CS was the word “BED” when capitalized
and the CR was blinking/flinching, smiling, and/or jumping to the word “bed.”
In addition to learning, extinction also occurred. Extinction refers to the gradual weakening of a
CR that results in the behavior decreasing or disappearing. In classical conditioning, extinction can occur
when a CS is no longer paired with an US. Because the subject did not respond to the word “bed” after
the third trial, the researchers concluded that extinction occurred.
There are some possible extraneous factors that could provide an alternate explanation for the
data. First, the squirtee was positioned in such a way that the observers were visible. It is possible that the
observers unintentionally offered nonverbal cues such as facial gestures or eye contact, which led the
squirtee to expect a squirt in the eye. This may have caused the squirtee to flinch or blink less frequently,
as the squirtee may have attempted to hold back any reactions after noticing the nonverbal cues. In
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addition, the squirtee could have observed the eye movement of the squirter and thus anticipated the
squirt, reducing the intensity of the reflex for similar reasons. Lastly, the squirtee was in an environment
in which other experiments were using the word “bed”, possibly causing the squirtee to flinch or blink at
times unrelated to the present experiment’s word sheet. Also, this may have confused the squirtee by
causing the squirtee to experience extinction, hearing other pronunciations of the word “bed” while not
being squirted. Despite possible extraneous factors that can occur in human classical conditioning, there
are many possible future experiments that can help researchers discover more about human conditioning.
Other avenues of research include differing test subjects, independent variables, aversive or positive
stimuli, and focus of research question. The importance of classical conditioning cannot be understated,
as many different applications may exist. There is a great amount of research already accomplished in the
classical conditioning field, but there are still many possible opportunities for further research.
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References
Domjan, M. (2005). The Essentials of Conditioning and Learning (Third ed.). Belmont, CA: Wadsworth,
Cendage Learning.