Preview o Avoidance procedure Chapter 10 Has to make a specific response to present an aversive stimuli from occurring Ie grabbing a handrail to avoid slipping Involves a negative contingency between an instrumental response and the aversive stimulus Increase the occurrence of instrumental behavior Active avoidance conditioning Involves a positive contingency the target response produces the aversive outcome You touch a hot stove you get burned Suppress instrumental responding Sometimes called passive avoidance o Punishment Avoidance Behavior o Origins of the study of avoidance behavior Vladamir Bechterev An extension of Pavlovs research Participants instructed to place finger on a metal plate o The CS a warning stimulus o The US brief shock through metal plate Participants quickly lift finger when shocked after a few trials learned to lift finger in response to warning stimulus o Participants determined whether or not they were exposed to the US If lifted finer to CS did not get shock delivered on that trial Constitutes significant departure from Pavlov Brogden Two groups of guinea pigs in a rotating wheel apparatus o CS a tone o US a shock Made guinea pig run and rotate the wheel o Classical conditioning group Shock always presented two seconds after the beginning of the tone Never achieved high level of performance o Avoidance conditioning group Shock also followed the tone when the animals did not make the conditioned response small movement to wheel If animal moved the wheel during the tone CS before the shock occurred the scheduled shock was omitted Conditioned response 100 of trials within 8 days of training o Proved avoidance conditioning is different from standard classical o The discriminated Avoidance Procedure conditioning Importance of warning signal in avoidance conditioning Discriminated signaled avoidance Involves discrete trials Often conducted in a shuttle box o Trial initiated by warning stimulus or CS o Things occurring after this depend on what participant does If subject makes target response before shock delivered CS is turned off and US omitted on that trial successful AVOIDANCE trial If subject fails to make required response during the CS US interval scheduled shock appears and remains on until response occurs whereupon both CS and US are terminated Results in escape from shock ESCAPE TRIAL o Most early trials are these o Consists of two compartments separated by opening at floor level o Animal placed one side of apparatus o CS presented at beginning o If subject crosses to other side before shock NO shock delived CS o At end of intertrial interval nect trial admin starting with animal in turned off second compartment o Animal shuttles back and forth between two sides on successive trials o Response titled Shuttle avoidance Two way shuttle avoidance Animal moves in different directions on successive trials One way shuttle avoidance Animal starts each trial on same side of apparatus and always moves in same direction to the other side Easier to learn o Two process Theory of Avoidance Assumes that 2 mechanisms are involved in avoidance learning COMPONENTS Classical Conditioning of fear to the CS o Has to occur first enables reinforcement in next phase o Activated by CS warning symbol will elicit fear because US is o US Aversive event on trials when organism fails to make avoidance aversive response o Treated as source of motivation for avoidance learning Instrumental reinforcement of the avoidance response through free reduction o Negative reinforcement for instrumental behavior o Learning of instrumental avoidance response occurs because response terminates CS and reduces the conditioned fear elicited by CS Classical and Instrumental processes depend on each other Predicts repeated interplay between classical and instrumental process Explains avoidance behavior in terms of escape from conditioned fear rather than in terms of the prevention shock Avoidance response prevents shock incidental by product in theory and not primary determinant of avoidance behavior EEscape is primary causal factor o Enables instrumental response to be reinforced by tangible event fear reduction rather than absence of something o Experimental Analysis of Avoidance behavior Acquired Drive Experiments Escape from fear FFE paradigm Classical conditioning of fear and instrumental reinforcement through fear reduction occur intermixed o GOAL of acquired drive experiment If processes make separate contributions to avoidance learning should demonstrate operation in situation where two types are not intermixed FIRST condition fear to a CS with pure classical conditioning procedure CS paired with US regardless of what subject does NEXT subjects are periodically exposed to fear eliciting CS and allowed to perform an instrumental response to turn off the CS reduce fear o No shocks scheduled Called acquired drive because drive to perform ths instrumental response fear was learned through classical cond rather than being innate hunger thirst Upheld that termination of a conditioned aversive stimulus is an effective reinforce for instrumental behavior Represents a transition from a passive fear reaction to an active coping strategy that helps to overcome fear and anxiety attendant to trauma Esmoris Arranz o Compared escape from fear learning after delayed and simultaneous conditioning in a shuttle box Initial phase rats confined to one side of box the shock side and received 10 pavlovian trials during each of three sessions CS 15 second audiovisual cue US 15second of mild foot shock o Delayed conditioning group always got the US at end of CS o Simultaneous conditioning group got US at same time as CS o Third group control CS and US unpaired o NEXT Barrier opened to other side of box and rats tested for escape from fear Rat placed on shock side with the CS turned on If rat moved to other side within a minute it turned off CS and was allowed to stay on other side for 30 seconds o Rats that did not move to the safe side within a minute were removed and placed in a holding box before starting next trial o Both delaed and simultaneous showed decreased latencies to escape from fear stimulus across trials indicating learning to escape from fear o No systematic changes in latency to escape evident in unpaired control group Independent measurement of fear during acquisition of avoidance behavior Based on assumption that if fear motivates and reinforced avoidance responding then conditioning of fear