Operant Behavior can involve BOTH Obviously, reinforcement schedules can control responding So can “rules”: heuristics algorithms concepts and concept formation operant conditioning can have rules, for example, the factors affecting reinforcement. Rate of Reinforcement In general, the faster the rate of reinforcement the stronger and more rapid the reinforcement Peaks at some point: asymptotic – Can no longer increase rate of responding – Do risk satiation Amount of Reinforcement In general, the MORE reinforcement the stronger and more rapid the responding. Again, at some point increasing the amount will not increase response ratesat asymptote Again, worry about habituation/satiation Delay of Reinforcement Critical that reinforcer is delivered ASAP after the response has occurred. Important for establishing contingency – Is really a contiguity issue – Doesn’t HAVE to be contiguous, but helps Why? – Responses occurring between the target response and the reinforcer may become paired with the reinforcer or punisher – Inadvertently reinforce or punish in between responses Example: Child hits sister, mother says “wait till your father gets home” – Child is setting table – Father walks in, hears about misbehavior, and spanks – Child connects table setting with spanking Reinforcer Quality Better quality = more and stronger responding BUT: Inverted U-shaped function – Too poor a quality = low responding – Too high a quality = satiation Think of the tenth piece of fudge: As good as the first one or two? Response Effort More effortful responses = lower response rates Must up the reinforcer rate, amount or quality to compensate for increased effort Again, an optimizing factor: – Low quality reinforcer not worth an effortful response Post-Reinforcement Pause Organism must have time to consume the reinforcer Longer pauses for more involved reinforcers – M&M vs. salt water taffy! – This is not disruptive as long as plan for it Satiation Hypothesis Responding decreases when animal “full” Satiation or Habituation? Satiation = satiety: animal has consumed as much as can consume Habituation = tired of it BOTH affect operant behavior often hard to tell which is which Extinction of Intermittently Reinforced Behavior The less often and the more inconsistently behavior is reinforced, the longer it will take to extinguish the behavior, other things being equal Behaviors that are reinforced on a “thin” schedule are more resistant to extinction than behaviors reinforced on a more dense schedule Behavior that is reinforced on a variable schedule will be more resistant to extinction than behavior reinforced on a fixed schedule Reducing Reinforcer Density Large amounts of behavior can be obtained with very little reinforcement using intermittent schedules – Initially, behavior needs dense schedule of reinforcement to establish it – preferably continuous reinforcement – As the behavior is strengthened, reinforcement can be gradually reduced in frequency Start with as low a density as the behavior can tolerate and decrease the density as responding is strengthened Schedule or Ratio Strain If reinforcement is reduced too quickly, signs of extinction may be observed – Response rate may slow down – Inconsistent responding may be seen – May see an increase in other responses If this happens, retreat to a denser reinforcement schedule Adding a conditioned reinforcer in between reinforcements can help bridge the gap Learned Helplessness What happens when animals lose their perceived control over consequences? LH in dogs • 2 separate shock locations: harness or alley-way/shuttlebox • Several procedures: – – – – Inescapable shock exposure instrumental escape/avoidance training Testing for chronic failure to escape TREATMENT • Removed barrier between sides • Opened observation windows on opposite side of box • Humans called dogs to safety side – Forced escape/avoidance – Recovery: testing again Learned helplessness Marty Seligman • Four groups of dogs Grp Grp Grp Grp Training I and II I Escapable/escapeable II Inescapable/inescapable III Escapable/inescapable IV Inescapable/escapable result Lasting effects run None not run None not run None not run Severe Remember, Seligman’s hypothesis was that NONE of the dogs would be significantly harmed. Did it work? • YES! • Learning contingency was critical • When learned that contingency was to escape- could overcome the first “learning rule” • Was one of first attempts at treatment • Why so important? One of first studies to suggest that you could be TAUGHT to overcome aversive events in your life! Key Factor = inescapability once learned not to escape (learned to be helpless)= not change Characteristics of L.H. • inescapability that produces phenomenon, not the shock itself • works under variety of procedures, conditions • very generalizeable, transferable • if take far enough, can make it a contingency rule for the animal, rather than specific contingency for specific situation(s) Symptoms of L.H. • • • • • passivity learned laziness retardation of learning somatic effects reduction of helplessness with time Clinical expressions of learned helplessness • School phobias and math anxiety • Abusive Relationships • Depression • Cultural learned helplessness Clinical expressions of learned helplessness • School phobias and math anxiety • Abusive Relationships • Depression • Cultural learned helplessness “Curing” or eliminating learned helplessness • Unlearn the rule • Reshape or recondition • Must be done in situation where organism cannot fail • Difficult to do- animals can “not” respond • UPenn program on relearning thoughts during test taking Two theories to explain • Competing response hypothesis – Dog learned motor responses which alleviated or attenuated shock – Those were used in shuttle situation, but ineffective – Thus learn the wrong responses • Adaptation hypothesis – Organisms sensitive to independence of events – Most situations: understand that shock is not dependent on their behavior – In LH: not make this distinction, rather shock WAS dependent on their behavior Does Extrinsic Reinforcement produce reductions in motivation? The answer depends on 1) How we define reinforcement 2) Whether we consider Learned Helplessness! Questions from the peanut gallery! • Massive literature on the effectiveness of positive reinforcement across many settings • BUT: concern…..is the effect of extrinsic reinforcement to reduce intrinsic reinforcement? – Reduces individuals feeling of competence? – Reliance on “things” rather than internal motivation Where did this debate come from? • 1970’s: began with cognitive revolution and backlash against behavior modification • 1994: meta-analysis by Cameron and Pierce suggested deleterious effects of positive reinforcement programs • Newer evidence in mixed – Some say it does – Some say it doesn’t Intrinsic vs. Extrinsic motivation • Intrinsic motivation: Deci (1975) – Motivation for which there is no recognizable reward except the activity itself – Cannot be attributed to external control • Extrinsic motivation = – motivation with recognizable reward – Behavior can be attributed to external reinforcer unrelated to activity • Harlow’s work from 1950’s: – If monkeys solved puzzle task with no external reinforcement, assumed that it was “internal” Problem with this definition: • Assume that reinforcers = things – Newer models of reinforcement assume reinforcers can be activities or access to activities – Based on traditional Equipotentiality principle of reinforcement: • Reinforcers are things • Reinforcers are a class of things – Once a reinforcer for someone, always a reinforcer – Once a reinforcer for a class of organisms, always a reinforcer for that class of organisms • Reinforcers are trans-situational Could this explain the earlier data? • Engage in behavior in anticipation of future events • Engage in behavior because activity is reinforcing in and of itself • This is NOT necessarily “intrinsic”, but due to narrow definition of internal and external reinforcers by others; Other interpretations • Horcones, 1987; Mawhinney, Dickinson and Taylor, 1989 • Intrinsic reinforcement = consequences which occur in absence of programming by others • Natural and automatic responses inevitably produced by the structural characteristics of the physical environment in which the human exists • Extrinsic reinforcers are those which are programmed by others • Intrinsically controlled behaviors = behavior controlled by unprogrammed consequences • Assumption is that intrinsic motivation is of greater value Deci’s studies • Examined changes in intrinsic motivation when extrinsic rewards were given • College students: solved “intrinsically interesting” puzzles: – Rewarded or not rewarded extrinsically for solving – Also condition where reward was offered but then unavailable – Presentation of rewards increased time on task; no rewards decreased time on task • College students examined headlines: – Rewards increased extrinsic motivation but withdrawal of rewards increased intrinsic motivation • Examined verbal praise for tangible rewards – Extrinsic reward group spent more time doing the task – But: both groups reported “liking” the task equally Cognitive Evaluation Theory • Deci and Ryan (1985) • Assumption: self determination and competence are innate human needs • Events facilitate or hinder feelings of competence or selfdetermination depending on perceived informational, controlling or amotivational significance • Two reward categories: – Task contingent – Quality dependent Eisenberger and Cameron (1996) • Also subdivides task-completion rewards category – Performance independent – Performance dependent • Intrinsic motivation most degraded when given tangible, anticipated rewards- devalues “self worth” • Alternative answer: learned helplessness – When have no control over outcomes, can develop LH Overjustification Hypothesis • With extrinsic rewards, may justify behavior based on those extrinsic rewards – Engage in the behavior because it is rewarded – If expect a reward, less likely to engage in behavior in absence of reward – Conclude that this means intrinsic reward is devalued • Overjustify the response: if a person is already performing a response and receiving no extrinsic reward, introduction of extrinsic reward will decrease intrinsic motivation – Performance becomes “overjustified” by external reward Problems with these theories • Methodological concerns: – Not examine behavior over long time horizon; only examine immediate effect – Which would you choose? No reward or reward for same activity? • Does this devalue your intrinsic motivation • Or does it make you an optimizing organism? Problems with these theories • Confusing rewards and reinforcement – Rewards = pleasant occurrence of an event, may or may not strengthen a response – Reinforcement: contingency between response and consequence strengthens the probability of a response • Data do not support overjustification hypothesis • Misinterpretation of behavioral principles: – Reinforcers are not necessarily things – Activity itself can be reinforcing – Confusing lack of perceived control with loss of intrinsic motivation • Alternative explanations from behavioral analysis: better theories of reinforcement Behavioral studies: • Important to use within-subject rather than across group comparisons – Too many individual differences – Examine change in reward value across an individual – Misinterpretation of “reward” vs reinforcer • When use within subjects methods, the devaluing tends to disappear. Perhaps the answer is in how we define reinforcement • Trans-situational hypothesis: – A reinforcer = a reinforcer across situations, subjects, etc. – A reinforcer MUST be a thing, not an activity • Modern view of reinforcement: – NOT transituational – NOT necessarily a thing – But we will leave that for another day!!!!!