PHAR2220 Lecture Notes - Lecture 15: Reinforcement, Hypothermia, Psychological Dependence
TOPIC&5:&DRUG&ADDICTION:&
&
Lecture&11:&The&Nature&of&Drug&Addiction:&
!
Definition&of&Drug/Alcohol&Addiction:&
&
WHO!Definition:!
-!Repeated!use!of!a!psychoactive!substance!or!substances,!to!the!extent!that!the!user!(referred!to!
as!an!addict)!!
o!Is!periodically!or!chronically!intoxicated!
o!Shows!a!compulsion!to!take!the!preferred!substances!(or!substances)!
o!Has!great!difficulty!in!voluntarily!ceasing!or!modifying!substance!use!
o!Exhibits!determination!to!obtain!psychoactive!substances!by!almost!any!means!
-!For!some!addictive!drugs!(but!not!all),!tolerance!is!prominent!and!a!withdrawal!syndrome!
frequently!occurs!when!substance!use!is!interrupted!
-!1960s:!WHO!recommended!that!addiction!be!abandoned!in!favour!of!dependence,!which!can!
exist!in!various!degrees!of!severity!
o!Dependence!is!neither!NECESSARY!nor!SUFFICIENT!for!addiction!
!
Psychology:&
&
Operant!conditioning!(instrumental!conditioning):!
-!Adjust!the!frequency!or!probability!of!a!behaviour!by!an!outcome!correlated!with!it!in!time!
!
Reinforcement:!!
-!An!outcome!of!a!behaviour,!usually!a!stimulus,!but!may!be!a!physiological!state,!that!increases!
the!probability!od!the!behaviour!that!produced!it,!or!preceded!it!in!time!
!
Punishment:!
-!An!outcome!of!a!behaviour,!usually!a!stimulus,!but!may!be!a!physiological!state,!that!decreases!
the!probability!of!the!behaviour!that!produced!it,!or!preceded!it!in!time!
!
o!Neither!type!of!outcome!has!to!be!associated!with!the!behaviour!100%!of!the!time!
!
Positive!Reinforcement:!
-!To!give!or!do!something!to!someone!that!is!‘rewarding’!and!therefore!results!in!the!increased!
probability!of!a!particular!behaviour!
-!Reward!is!not!the!same!as!pleasure!(usually!go!together,!but!not!always)!
!
Negative!Reinforcement:!
-!Taking!away!punishing/aversive!stimuli!to!increase!the!probability!of!a!particular!behaviour!
o!E.g.!removing!burning!by!taking!your!hand!off!a!hot!stove!is!negative!reinforcement!of!
lifting!the!hand!
!
Reward:!
-!Can!be!specific!stimuli:!food,!water,!social!status,!sex!partners!etc!
-!However,!it!is!a!consummatory!behaviour!associated!with!rewards!that!is!most!rewarding:!eating!
food,!drinking!water,!performing!well!socially,!having!sex!etc!
!
Reinforcement!Therapies:!
-!Premack!(1959):!had!a!response&probability&differential!hypothesis!of!rewards!
o!The!more!probable!response!is!the!reinforcer!
o!E.g.!eating!food!is!the!more!probable!by!a!rat!than!pressing!a!lever!
!!Therefore,!making!food!availability!contingent!on!lever-pressing!will!reinforce!
lever-pressing!
-!Timberlake!and!Allison!(1974)!elaborated!on!this!to!form!the!(consummatory)!Response!
deprivation!hypothesis!
o!Response!deprivation!‘occurs!in!the!contingency!if,!in!performing!the!instrumental!
response!at!operant!baseline,!the!subject!would!perform!less!than!his!operant!baseline!of!
the!contingent!response’!
-!Heath!&!Warren!(1978)!showed!that!a!response!can!be!both!a!reward!or!a!punishment,!
depending!on!response!deprivation!and!response!satiation!relative!to!the!contingent!
relationship!–!a!Response!Satiation!Hypothesis!
!
The!Relativity!of!Rewards:!
-!Donald!Heth:!in!an!experiment!I!conducted!as!a!student!for!Prof!Heth!and!the!University!of!
Alberta!with!capuchin!monkeys,!I!found!that!stimulus!deprivation!and!satiation!also!resulted!in!
the!stimuli*!being!either!a!reward!or!a!punisher,!respectively!
-!This!is!the!Stimulus&Deprivation&Hypothesis!of!reinforcement!
-!Jazz!music!and!a!psychedelic!colour!display!were!the!stimuli!–!in!1970s!
-!Whether!an!outcome!of!a!response!is!reward!or!punishment!depends!on!the!rates!of!the!
instrumental!response!and!the!outcome!response!or!stimulus,!relative!to!the!operant!‘free’!
baseline!response!or!‘voluntary’!stimulus!exposure,!and!the!contingency!between!them!
o!Deprivation!Hypothesis!
!
Pleasure!and!Pain!Vs!Reinforcement!and!Punishment:!
-!The!Deprivation!Hypothesis!of!Reinforcement!are!not!concerned!with!‘pleasure’!and!‘pain’!
o!These!are!subjective!emotional!experiences!usually!(but!not!always)!associated!with!
positive!reinforcement!and!punishment!
o!For!E.g.!the!perhaps!apocryphal!story!of!psychology!students!as!a!class!positively!
reinforcing!a!teacher’s!behavioural!tic,!such!as!tugging!on!an!ear,!with!increased!
attention!
o!Another!example!is!in!two!experiments,!one!with!morphine!and!one!with!cocaine!–!
people!could!press!two!buttons!
!!One!gave!them!an!intravenous!injection!of!saline,!the!other!gave!them!the!drug!
!!People!would!choose!the!drug!button!over!the!saline!lever!even!if!the!doses!of!
the!drugs!were!so!low!that!they!reported!no!subjective!effects!of!the!drugs!at!all!
!
The!Physiological!Role!of!Pleasure:!
-!Cabanac!(1971)!related!pleasure!and!pain!to!physiological!states!
-!Much!of!his!work!was!based!on!pleasure!from!temperatures!and!tastes!
-!He!showed!that!whether!or!not!cold!water!is!pleasurable!or!unpleasant!depends!on!the!state!of!
your!body:!
o!When!you!are!hot,!cold!water!is!pleasant,!and!when!you!are!cold!it!is!unpleasant!
-!How!pleasurable!food!is,!depends!on!how!much!your!body!needs,!or!anticipates!needs!for!food!
(i.e.!food!deprivations)!
!
Alliesthesia:!
-!Cabanac!calle!the!dependence!of!Pleasure!on!physiological!state!
-!Alliesthesia:!the!production!of!emotional!states!of!pleasure!and!unpleasantness!to!maintain!
optimal!physiological!homeostasis!
o!He!used!water!temperature!as!an!example!
o!When!your!body!is!overheated,!cold!water!is!pleasant!and!warm!water!is!unpleasant!!
o!When!your!body!is!hypothermic,!warm!water!is!pleasant,!and!cold!water!is!unpleasant!
!
Pleasure!and!Pain!–!the!common!currency:!
-!Cabanac!(1992)!argued!that!pleasure!and!pain!(the!latter!including!anticipated!pain!–!fear!and!
anxiety)!are!the!subjective!equivalents!of!the!brain!producing!a!‘common!currency’!to!be!able!to!
trade-off!between!competing!motivations!
-!For!E.g.!a!wild!rat!in!a!burrow!must!have!some!means!of!trading!off!leaving!the!burrow!to!find!
food!or!a!mate,!against!the!predation!by!cats,!dogs!and!birds!of!prey!
-!The!stronger!the!need!for!food!or!a!mate!(the!greater!the!anticipated!pleasure)!the!more!likely!
the!rat!will!leave!even!if!he!has!to!face!predators!
-!The!more!likely!the!predators,!the!stronger!the!fear,!the!less!likely!the!rat!will!leave…it!will!take!a!
stronger!pleasure!to!weigh!against!the!fear!
-!Once!out!of!the!burrow,!the!rat!has!to!decide!between!foraging!for!food!or!finding!a!mate!
o!Again,!the!potential!pleasures!of!the!two!outcomes!are!weighed!against!each!other,!and!
the!rat!will!optimise!his!pleasure!
o!The!more!deprived!food,!the!more!likely!it!will!choose!food!over!a!mate,!and!vice!versa!
-!Thus,!the!experiences!of!pleasure!and!pain!are!the!common!currency!that!allows!trade-offs!for!
behavioural!options!to!be!selected!
!
Measuring!‘addiction’!in!animals:!
-!Animals,!including!rats!and!monkeys,!will!learn!to!press!levers!in!order!to!get!intravenous!
infusion!of!certain!drugs!
-!These!drugs!include!(but!are!not!limited!to)!
o!Morphine!
o!Cocaine!
o!Amphetamine!
o!Heroin!
-!Ultrasonic!vocalisations!in!rats!
o!50!kHz!calls!indicate!happy/pleasure!
o!22!kHz!calls!indicate!dear/pain!
!
Dose!Decreases:!
-!Animals!titrate!their!responding!to!take!into!account!changes!in!dose!
-!If!we!decrease!the!dose!per!infusion,!the!animals!increase!their!responding!so!that!the!get!the!
same!amount!of!drug!
-!This!is!an!interesting!situation,!where!giving%less%reward%produces%more%responding!
-!It!supports!the!deprivation!and!the!alliesthesia!hypotheses!of!reward!and!pleasure!
!
Dose!Increases:!
-!If!we!increase!the!dose!per!infusion,!rats!will!decrease!their!response!rate!
-!This!appears!to!be!a!case!where!increasing%the%reward%decreases%responding%&
-!It!supports!the!deprivation!(Satiation!bit)!hypothesis!of!reinforcement,!and!the!Alliesthesia!
hypothesis!of!pleasure&
-!Apparently,!the!animals!have!an!operant!baseline!preferred!dose,!and!will!alter!their!behaviour!
to!titrate!that!dose!accordingly&
-!Cabanac!would!probably!argue!that!the!drug!is!producing!an!optimal!homeostasis&
&
!
!
!
Document Summary
The deprivation hypothesis of reinforcement are not concerned with pleasure" and pain" o these are subjective emotional experiences usually (but not always) associated with positive reinforcement and punishment o for e. g. the perhaps apocryphal story of psychology students as a class positively reinforcing a teacher"s behavioural tic, such as tugging on an ear, with increased attention o another example is in two experiments, one with morphine and one with cocaine people could press two buttons. Alliesthesia: the production of emotional states of pleasure and unpleasantness to maintain optimal physiological homeostasis o he used water temperature as an example o when your body is overheated, cold water is pleasant and warm water is unpleasant o when your body is hypothermic, warm water is pleasant, and cold water is unpleasant. These drugs include (but are not limited to) o morphine o cocaine o amphetamine o heroin.
