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Lecture 7

PSYC 2330 Lecture Notes - Lecture 7: Leon Kamin, Tegmentum, Classical Conditioning

Course Code
PSYC 2330
Francesco Leri

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Thursday, September 25 2012
PSYC 2330
Lecture 8
Activity of dopaminergic neurons in the ventral tegmental area should increase when a:
a) neutral stimulus such as a tone is presented before conditioning
b) a US is presented after a CS
c) US is not presented after a CS
d) a CS is presented
e) all of the above
I guess (d) (Correct!)
Blocking (Leon Kamin)
The blocking group receive extra conditioning compared to the control group
In phase 2, a tone is added to the light at the same time
The question is how much conditioning is generated to the tone that was added
Everyone is looking for meaningful predictors. Once you have an effective predictors,
additional predictors are ignored because their predictive value is redundant
This experiment is important because it shows that:
Conditioning is not an automatic result of CS-US pairings
For conditioning to occur, the CS must be informative about the US in a novel was
When two CSs are used (a & b), the association or expectation at the beginning of a trial would
be the sum of the strengths
sum of Vab = Va + Vb
Therefore, the amount of conditioning on a compound trial in which a and b occur together
would be
deltaVa = deltaVb = alpha * beta (Vmax – Sum of Vab)
In the blocking group, if the Vmax for the light (L) = 1.0, then:
VL = 1.0 at the end of phase 1 (because of extensive L conditioning)
The animal is perfectly conditioned at the end of the conditioning
When the light and the tone (T) are presented in combination on trial 1 of phase 2
sumVLT = VL + VT = 1.0 + 0 = 1.0
Therefor, the amount of conditioning to the T in the blocking group after 1 trial of conditioning
with the LT compound is:
deltaVT = alpha * beta (Vmax – sum of VLT) = 0.3(1.0 – 1.0) = 0
alpha * beta = 0.3
How much do the animals learn after adding the tone?
They learn nothing new about the light (They already know all there is to know about the
They learn nothing new about the tone (They are using the information about the light only)
Overexpectation Effect
CS/US info
Tone followed by shock
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