Invitation to Psychology

308 Chapter 9 Learning and Conditioning

mouth watering. These new salivary responses

clearly were not inborn, so they must have been

acquired through experience.

At first, Pavlov treated the dog’s drooling as

just an annoying secretion. But he quickly realized

that his assistant had stumbled onto an important

phenomenon, one that Pavlov came to believe

was the basis of most learning in human beings

and other animals (Pavlov, 1927). He called that

phenomenon a “conditional” reflex because it de-

pended on environmental conditions. Later, an er-

ror in the translation of his writings transformed

“conditional” into “conditioned,” the word most

commonly used today.

Pavlov soon dropped what he had been doing

and turned to the study of conditioned reflexes, to

which he devoted the last three decades of his life.

Why were his dogs salivating to things other than

food?

New Reflexes from Old LO 9.1

Pavlov initially speculated about what his dogs

might be thinking and feeling when they drooled

before getting their food. Was the doggy equiva-

lent of “Oh boy, this means chow time” going

through their minds? He soon decided, however,

that such speculation was pointless. Instead, he fo-

cused on analyzing the environment in which the

conditioned reflex arose.

The original salivary reflex, according to

Pavlov, consisted of an unconditioned stimulus (US),

food in the dog’s mouth, and an unconditioned

response (UR), salivation. By an unconditioned

unconditioned stimu-
lus (US) The classical-
conditioning term for
a stimulus that already
elicits a certain response
without additional
learning.

unconditioned
response (UR) The
classical-conditioning
term for a response elic-
ited by an unconditioned
stimulus.

You are about to learn...

•    how classical conditioning explains why a dog

might salivate when it sees a light bulb or hears

a buzzer.

•    four important features of classical conditioning.

•    what is actually learned in classical conditioning.

Classical Conditioning

At the turn of the twentieth century, the great

Russian physiologist Ivan Pavlov (1849–1936) was

studying salivation in dogs as part of a research

program on digestion. One of his procedures was

to make a surgical opening in a dog’s cheek and

insert a tube that conducted saliva away from the

animal’s salivary gland so that the saliva could be

measured. To stimulate the reflexive flow of saliva,

Pavlov placed meat powder or other food in the

dog’s mouth (see Figure 9.1).

Pavlov was a truly dedicated scientific ob-

server. Many years later, as he lay dying, he even

dictated his sensations for posterity! And he

instilled in his students and assistants the same

passion for detail. During his salivation stud-

ies, one of the assistants noticed something that

most people would have overlooked or dismissed

as trivial. After a dog had been brought to the

laboratory a few times, it would start to salivate

before the food was placed in its mouth. The sight

or smell of the food, the dish in which the food

was kept, and even the sight of the person who

delivered the food were enough to start the dog’s

FigURE 9.1 Pavlov’s Method

The photo shows Ivan Pavlov (in the white beard), flanked by his students and a canine subject. The drawing depicts

an apparatus similar to the one he used; saliva from a dog’s cheek flowed down a tube and was measured by the

movement of a needle on a revolving drum.