PSYC3011 Learning and Behaviour

PSYC3011 Learning and Behaviour Extinction as inhibition - Extinction creates a new inhibitory association that counteracts original association o o o

Blue: excitatory connect Red: inhibitory – CS blocks expectation of US Neutralise each other  won’t get responses

Inhibition - Conditioned inhibition o Paired: good conditioning (CS at same time as US) o Explicitly unpaired: conditioned inhibition (CS not on when US is on)  Make sure they never overlap  No responding when inhibitor comes on - how do we know they’ve learned? o  

Excitatory CS – blue Inhibitory CS – green: safety signal (if US is aversive) or frustration signal (if US is attractive) - Tests for inhibition o Summation test: S reduces responding to another CS+  Pre-trained CS then add another CS  CS1no US; CS2US o Retardation test: subsequent learning of an S-US association is impaired  Switch to explicitly paired schedule – S that was negatively correlated is now positive  Need to unlearn inhibitory and then learn excitatory association  E.g. you get bullied on the bus, you don’t when your sister is with you  Sister is an inhibitor  Sister starts bullying you – need to unlearn and then learn - Inhibition and the R-W model  To get inhibition, you need to be expecting the US and it doesn’t occur o “A” (excitatory CS) is presented with a new CS (“X”) and no US is delivered  Negative discrepancy: US expected but absent   = 0  V is negative  Inhibitor needs to have a negative associative strength that is equal to the positive excitor  cancel out - Conditioned inhibition o Context is associated with extra shocks  contextual conditioning (excitatory stimulus) Inhibition and excitation - If omission of expected reinforcement is sufficient to condition inhibition to added CS o L  shock, T  L  no shock, T = CI (red) o L  shock, L  no shock, L is extinguished (blue)

PSYC3011 Learning and Behaviour

Prediction - V =      – V) o A & B are excitatory CSs (previously paired with US) o X is a conditioned inhibitor Conditioning Extinction Test A US; B  US B  nothing B? X&A  no US A  US; B  US X&B  nothing B? X&A  no US o X produces less extinction  If inhibitory strength of X is equal to the excitatory strength of B, there should be no learning at all on the extinction trials o Sister example – bully undergoes program and stops bullying but you only catch the bust with your sister  you won’t expect the bully to act because she’s there so you don’t learn that he’s stopped - Significance for anxiety therapy  if they attach to something that becomes and inhibitor that makes them know that they are safe, they won’t experience extinction o Inhibitor prevents extinction of an excitor - According to R-W, what should happen when a novel CS (Y) is combined with an inhibitory CS (X) and reinforced? Conditioning Test Y  US Y? X+Y  US Y?  X=inhibitor  X&Y still results in US  Y is especially strong o

-

 – V) 

+ V) – double negative = +

 V is especially large o Super conditioning According to R-W, what should happen when an inhibitory CS (X) is repeatedly presented on its own without the US? o V =      – V) o V =     (0 – – V)  Take a CI (-V) and present on its own without any US: R-W predicts extinction of inhibition  If X is an inhibitor, V is negative,  = 0 o  – V) will be positive  But numerous experiments show that CIs do not extinguish  X retains its inhibitory strength (R-W is wrong)  What should happen when an inhibitory CS (X) is repeatedly presented with a neutral CS (Y) and no US?  V is positive for both X and Y  Y acquires strength