Learning lec 8 - Dr.Hugo PDF

Preview

Summary

Dr.Hugo...

Description

PSYC Learning Lecture 8: Week 11 November 23rd, 2020 -

Brain stimulation Chaining & shaping Advantage of token reinforcement Extinction – side effects, rate – factors that leave to faster or slower… Study

Theories of Reinforcement - Skinners definition: the consequence to a behaviour will increase - Reinforcement: consequences to a behaviour is followed by a stimulus that will affect future probability or reinforcement - Emitter behaviour – operant followed by a consequence stimulus (reinforcer) – - How do we know when a stimulus is a reinforcer? o Being reinforcer (circular) – make predictions 1. Reinforcer as stimuli a. Drive reduction b. Incentive motivation c. Bran stimulation – reward circuit 2. Reinforcer as behaviours a. Premack principle Drive Reduction - Motivation, innate, urge that comes from within – motivation theory’s - An event is reinforcing to the extent that is associated with a reduction in some type of physiological drive: Hull (1943) - Reductio, satisfying physiological drive - Hunger = drive, food = stimuli - Play, hunger, thirst, sex, pain avoidance, etc. - Any stimulus that will satisfy those drives will be a reinforcer - Ex. If hunger, if eat, then that food is a reinforcer Incentive Motivation - Reinforcer actually increase drive rather than reducing them - Reinforces are incentives that elicit responding - Need prior experience with the reinforcer - Perform in order to get the reinforcer - Pulls you into action, and increases the drive - Working towards getting the reinforcer - Reinforcer Increases drive - Pull you into responding - For a reinforcer to be incentive – need prior value before hand

-

Need to know what it is

What’s the difference b/w drive reduction and incentive motivation? - Difference between push and pull... o Drives push us into action (hunger pushes us into action) o Incentives entices/pulls us into action (chocolate pulls us into action) - Reinforcer priming… o After small piece of food dogs will want more – focusing on giver o Give dog an incentive since they have experience with the stimulus – the reinforcer primed the situation o If animal is hungry and give it a small piece of food – it will be pushed to drive o Some element towards drive should reduce it o Drive reduction give rise to incentive o Food pulls sends and incentive to perform behaviour o The incentive motivation came out in part because there were problems – small food increases reinforcer Chain & Shaping - More complex behaviour through reinforcement - Linking together multiple simple behaviour - Each simple behaviour is conditioned and only provide reinforcement with multiple - Ex. Pigeon – start with each step o Press lever (condition it by rewarding) o Peck disc (reward) o Link both together to make a chain, so now the pigeon will only get reinforcement when presses lever and then disc o Then later get reward at the end once in sequence - Complex behaviour = shaping o We have to shape the desired behaviour o Encourage them to do things to get them closer to what you want o Successive approximation of desired behaviour o Closer and closer to finally getting behaviour that you want - Ex. Teaching pigeon in playing ping pong o Get pigeon used to ping pong ball o Increase frequency of pigeon getting close to ball – then touch (reward) o Pushing ball = reward o Once that’s done, then next step to hit ball harder o Get reward only when hit ball o Gradually reinforcing approximation of behaviour then get complex behaviour o Limitations of operant condition - Keller & Marian Breland o Operant condition to get complex behaviour - problems:

o racoons start thinking coin is food when reinforced to pick food – couldn’t condition it out animal o behaviour was too similar to animal natural behaviour  instinctive drift – if behaviour is too similar then instinct will win – instinctive will disrupt conditioning process -not strong enough to overcome  biological limits on conditioning process  instinct takes over condition Brain Stimulation - an actual reward centre/circuitry in our brain that would be stimulated by reinforcers - highly used to account for addiction - reward circuitry in our brain – reinforcers activate the reward centre in the brain - drugs that are addictive stimulate reward circuits in the brain - they activate them in specific neurotransmitter of reward (dopamine) - increase release of dopamine Dopamine Reward System - chemical released by neurons and activates other neurons in the brain - VTA: Ventral Tegmental Area - Prefrontal Cortex - Nucleus Accumbens - If levels of dopamine are too high your psychosis = disorganized thoughts, hallucination , thinking people are there to get you – dysfunction of dopamine - Too much dopamine will cause schizophrenic symptoms - High stimulation of dopamine to prefrontal cortex - Low dopamine = Parkinson’s – Tremor Reward System - If you put electrodes (wire) into the brain, and hook it up to send mild electric current to stimulate neuron, activate current - If you activate reward system into the electrode, neurons will fire, dopamine will fire - If you hook up that electrode to bar lever, and press lever it activates current then will press it to get dopamine (it feels good) – just to get that current in reward Sampling dopamine in the nucellus accumebns - Collect compounds form brain to analyze that sample and see level of dopamine - Put a probe – small thin tube into rat brain, hook to tube and while rat is awake and behaving, could sample fluid of brain and measure dopamine levels - Sample fluid from NA to see if there in changes when rat receives dopamine level Dopamine release during instrumental lever pressing - Salamone (1994): examined dopamine level of rats with lever pressing - Four groups:

o o o o -

FR 5 schedule Food pellet Laboratory chow Food deprived = Baseline Control Group

Wanted to see if it just reinforcer process or reward Measured dopamine levels – see if reinforcer activated their bar pressing Different control o Some trained to press is FR 5 schedule – ever 5 presses will get delivery of food pallet o Reinforcer food and maintain porbability of pressing bar to retain more food o Is it just food pallet or behaviour? - Chamber given bunch of palettes didn’t have to work for them - no bar pressing – pile of food palettes is presented and does that have an effect on dopamine - Food? – third group that had their typical food given to them in lab – not pressing just given normal food - Food deprived – never allowed to bar press or eat 4 groups - They collected the sample before and during task - Bar pressing, eat chow, or food palettes Dopamine level vs. Baseline - Baseline = before start eating task - Control group never got food = 100%, no change in dopamine levels - Collect dopamine samples, give chow (before and during eating) – dopamine about the same - Food pellets = 100% - Other rats of FR5 (low, med, high) - Those that were low, bar pressed and were getting food palettes showed an increase of dopamine in NA but was not statistically different – mean is higher, but that effect could be a fluke due to chance - (high) = statistically about different control groups – increase of dopamine levels - Not due to the food – - Chow ad palettes got food palette for bar pressing – not just the food but it is the work for retaining stimulus – engaging in behaviour then getting reward which increases dopamine levels – activates reward circuitry - Increase dopamine levels in NA - Working a retaining reinforcer is more rewarding in brain - Working for $100 – more than someone who does nothing and get $100 - Why is the medium rate and high rate different? o Variability in comparison between those groups o Comparison is not different o Mean is different but not statistically different

FR 5 Schedule - Low responders – no DA change - Medium responders – increase DA in NAcc - High responders – increases DA in NAcc - Only med and high showed an increase in dopamine that was meaningful, and this increase was higher than rats that received food pellet and chow Food pellet and lab chow groups ate a lot food but no change in NAcc DA - Operant behaviour leading to a reinforcer activated the dopaminergic reward system - Operant behaviour activates dopamine reward system - Stimuli in regular bases of outcomes in reward circuitry to keep them engaged - If you give reward without operant behaviour response reward there will be no increase, but if there is reward with high enough response rate then there is an increase Premack Principle - A high-probability activity will reinforce a low probability active - One behaviour can increase/ or reinforce a low prob activity - Ex. Going to the movie = high rank - Studying = low rank - Responses can reinforce other responses - Behaviours can be ranked in term of preference - Always study first, then watch movie, not vice versa - High ranked behaviour will increase the low ranked behaviour - Walking next – and likes sniffing fire hygiene -highly ranked for her - Do something then go chase a bug – behaviour to reinforce another behaviour - First study to take kids- examine how much they prefer lollipop versus pin ball to increase behaviour of eating candy followed by pin ball - Taking behaviour to reinforce other behaviours - High (often) is good reinforce for lower freq. of behaviour Side effects of Extinction & Factors of how quick Extinction occurs Side Effects - Aversive side effects not just for client but other too - Increase in behavioural frequency - Increase in behavioural variability – turn car on, keep trying, then put key back out etc. o Same outcome of car turning on - A re-emergence of other behaviours that were previously reinforced - If applying extinction for behaviours – do something less socially acceptable - Ex. Teacher attention is raise hands – teacher does not call in the behaviour that could potentially contact other reinforcer - “Emotional” behaviour – sometimes violent: melt down behaviour of screaming etc. -...