Biomedical Engineering Reference
In-Depth Information
principle behind advertisements. Pavlov was a Russian biologist research-
ing the secretion of saliva in dogs. He inserted a fistula in the throat of a
dog and tapped the saliva while the dog was watching the food. At a cer-
tain point, Pavlov discovered that the dog started to salivate before the
food was even in the laboratory; the dog responded to the sound of the
food server
'
s footsteps as he walked down the corridor bringing the food.
The sound of the footsteps had become a trigger to start the saliva reflex.
The basic principle of classical conditioning is that an original stimulus
(visible food) is connected in time and space with a new stimulus (foot-
steps), and that the new stimulus can evoke the same reaction as the origi-
nal stimulus after a while. The central element in classical conditioning is
that by perceiving two stimuli together, an association is created in our
brain. Due to this association, both stimuli can evoke the reflex that once
was only connected to the original stimulus. Once the connection is estab-
lished, the neutral stimulus can evoke a reflex that originally didn
t
belong to that stimulus. We call this association a conditioned response
(in this case, salivation) to the new stimulus. The connection keeps on
working when the original evoking stimulus (food, in the case of the dog)
is not active or present anymore. The new stimulus has become a condi-
tioned stimulus.
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Anxiety
evoking
stimulus
Anxiety
response
Risk
sensitivity
Neutral
stimulus
Simultaneous experience =
classical conditioning
Conditioned
anxiety
response
Risk
sensitivity
Conditioned
stimulus
Later experiences
Pavlov continued his experiments and started to ring a bell just
before the server would enter the corridor of the lab. After some time,
