Principles of Learning – Lecture 15
(From last week)
- Emotional value: how much you like or dislike something
- Motivational value: how much you want it or not
- The substance-dependent individual wants to stop (constant desire); profound dislike for
the drugs, but the behaviour continues.
Clear dissociation between what they say they don’t like & what they do
- Experiment: dopamine involved in liking but not wanting.
“Broke” the wanting system in the brain (made it go away); used a toxin to kill
neurons in the brain in the VTA that contains dopamine neurons (killed them).
- Following these lesions, the animals had lower dopamine levels; produced sever
aphagia (starve themselves to death). If you test the facial reactions of the animals
to sweet & bitter tastes, they produce the same reactions that they normally
would. This means that they still like the food, they just do not want the food =
motivationally blind; does not care.
- If lesions created in half of the brain, only food placed in the area of the brain
hemisphere containing dopamine will be eaten. Food placed on the other half will
Reinforcement is a motivational construct
Effectiveness of Reinforcement
Drive, incentive value of S*, delay of reinforcement, stimulus control, schedule of
reinforcement - SG= goal stimulus
- RG= responses in the goal box (salivating, etc.)
After a few trials, when the rat is placed in the start box, it will begin to salivate
slightly (G = fractional responses)
Hull says that these conditioned responses (salivation) become stimuli –
salivates more when it turns right.
- Response: turning left or right