Drive Reinforcement Incentive ¢  ¢â‚¬â€œTo respond...

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Transcript of Drive Reinforcement Incentive ¢  ¢â‚¬â€œTo respond...

  • Drive

    Reinforcement

    Incentive

    Basic concepts

  • Incentive value: Hedonic dimension

    • Appetitive: any stimulus the organism is willing to work to

    obtain it.

    • Aversive: any stimulus the organism is willing to work to

    eliminate from its surrounding.

    • Obvious examples: –Food for a hungry animal.

    –Pain for a healthy animal.

    • What happens when the stimulus has no obvious hedonic

    value?

    • Betta fish are territorial and aggressively defend their area

    from intruders.

    • Do Betta males treat an intruder as an appetitive or

    aversive stimulus?

    • Pair a stimulus with their own reflection on a mirror.

    • Would they work to produce a reflection or to eliminate it?

    Thompson, Amer Zool, 1966, 6, 629-641.

    • Bettas learn to

    swim through a

    hole to activate

    a model of

    another Betta.

  • Incentive value: Progressive ratio

    • How can the value of an incentive be assessed?

    • Progressive ratio schedules: an increasing number of responses is required to obtain the reward.

    • Example: 1 – 4 – 9 – 13 – 17 – 21 – 25 …

    • Breakpoint: the ratio in which no responses occur over x minutes (e.g., 5 min without responding).

    • The amount of work is a function of the incentive value of the reward.

    Rats (pellets) Pigeons (pellets) Rats (alcohol)

  • Incentive motivation: wanting vs. liking

    • The evolutionary function of motivation: To fulfill physiological needs.

    • But motivation is also fueled by pleasure.

    • Two separate but interconnected subcortical processes direct motivation:

    • Wanting: incentive salience (desire for a reward).

    • Liking: hedonic pleasure (procuring reward beyond sensory experience).

    • Signals acquire incentive salience (autoshaping).

    [Video]

  • • Signals become “motivational magnets” directing behavior (PIT).

    Pavlovian Instrumental Transfer-of-control

    Phase Phase Test

    (fear conditioning) (active avoidance)

    ---------------------------------------------------------------------------------------------------------

    CS→Shock Response→noShock CS→Response?

    noResponse→Shock

    ---------------------------------------------------------------------------------------------------------

    CS

    Sh (fear)

    Manipulandum

    R

    CSManipulandum PLUS

    +O Sh

    (fear) Sh

    (fear) Sh

    (fear)

    RR!

    Incentive motivation: wanting vs. liking

  • • Liking is reflected in behavior (taste reactivity test).

    • Wanting depends on the dopaminergic mesolimbic system.

    • Liking depends on opioid stimulation in “hot spots” within this system.

    Incentive motivation: wanting vs. liking [Video]

  • NAc shell

    Caudal VP

    Hedonic “hot spots”: opioid stimulation increases liking.

    Dopaminergic stimulation increases wanting.

    Robinson et al., Current Topics in Behavioral Neuroscience, 2015, 27 (DOI 10.1007/7854_2015_387).

    Incentive motivation: wanting vs. liking

  • Addiction

    • Characterized by a progressive dissociation of wanting and liking.

    • Repeated consumption leads to incentive salience (wanting).

    • Repeated experience reduces pleasure (liking).

    • Tolerance leads to increased doses, which sensitizes the reward system.

    • Withdrawal symptoms can lead to relapse.

    Berridge et al., Current Opinion in Pharmacology, 2009, 9, 65-73.

    Incentive motivation: wanting vs. liking

  • http://www.ted.com/index.php/talks/barry_schwartz_on_the_paradox_of_choice.html Duration: 19.17 min

    Incentive motivation: choice [Video]

    http://www.ted.com/index.php/talks/barry_schwartz_on_the_paradox_of_choice.html

  • •Official dogma of Western industrial societies:

    •More choice → More freedom → Increase welfare

    •An explosion of choice: in food, electronics, cell phones, health care, marriage options, work, lifestyles…

    •This is both good and bad. What’s bad about it?

    •Consequences of too many choices:

    •Regret and anticipated regret (paralysis)

    •Opportunity cost

    •Escalation of expectations

    •Self-blame

    •The secret to happiness is low expectations

    Paradox of choice: summary

  • Choice and incentive value

    • Do animals have the ability to choose?

    • Not only do animals exhibit free choice, but this is also a sensitive measure of incentive value.

    • Forced choice: –To respond vs. not to respond.

    • Free choice: –To respond to one option, or

    –To respond to another option, or

    –Not to respond to any option (do something else).

    • In some cases, forced and free choice produce similar results.

    Papini et al., Learning & Motivation, 2001, 32, 434-456.

    • Rats prefer pellets to 2% sucrose.

    • But 30% sucrose to pellets

    • After free delivery of 2% sucrose,

    rats autoshape for pellets at a

    higher level than after free

    delivery of 30% sucrose.

    • Thus, they value 30% sucrose

    more than pellets, but

    • 2% sucrose less than pellets.

  • Choice and incentive value

    • In other cases, forced choice is less sensitive than free choice.

    • Rats do not differentiate between a lever paired with 12 pellets vs. a lever paired with 2 pellets when they

    experience one lever at a time (forced choice).

    • However, they show preference for the 12-pellet lever when they have a free choice.

    • Why is free choice a more sensitive measure for detecting incentive value?

    • It allows a direct, simultaneous comparison of incentive expectations.

    Conrad & Papini, Journal of Experimental Psychology: Animal Learning & Cognition, 2018, 44, 422-440.

  • Choice and incentive value

    • Free choice also sometimes yields unexpected results.

    • When rats experience an incentive downshift, they actually respond in opposite directions in both types of

    choice situations, even within the same session.

    • Forced choice: they respond slightly more to the downshifted lever (12-to-2 pellets) than to the unshifted

    lever (2-to-2 pellets).

    • Free choice: they switch to the unshifted lever, at least for a few trials.

    Conrad & Papini, Journal of Experimental Psychology: Animal Learning & Cognition, 2018, 44, 422-440.