psych 104: learning and adaptation

what is learning

• learning is a process by which experiences can lead to changes in behaviour and capabilities

measuring learning?

• learning is measured through change in performance

  • e.g. sports games, achievement tests, learning how to walk (crawling - walking - running)

the big three

• habituation (event alone)

• classical conditioning (event event)

• operant conditioning (behaviour event)

habituation + how does it differ from sensory adaptation?

• we respond less strongly over time to a particular stimuli

• through repeated presentations

• occurs in the brain, not in the receptors (main difference between habituation and sensory adaptation)

habituation discovered by what animal?

• sea slug

  • poking its gills over time - stops reacting

    • learns that the poking isn’t dangerous

    • learns how to react to poking

sensitization

• opposite of habituation

• an increase in the strength of response to a certain stimuli

specificity between habituation and sensitization

• habituation: specific

• sensitization: non specific

conditioning

• British philosophers believed that we acquire almost all our knowledge via conditioning

  • conditioning = forming associations between stimuli

  • simple associations → complex tasks

Ivan Pavlov

• digestive processes in animals

  • in the process, discovered classical conditioning

  • “conditioned reflexes”

Ivan pavlov - dog example

1. each morning, a person enters through a door with a bell and fed the dogs

2. dogs start salivating when the bell rings

dogs associate bell with food = elicits salivation!

classical conditioning

• the process of association became known as classical (pavlovian) conditioning

  • a neutral stimulus (NS) becomes paired with the occurrence of another stimulus (US - unconditioned stimulus)

unconditioned stimulus

• biologically significant stimulus that naturally produces a response

  • e.g. food → salivation

conditioned stimulus

• previously neutral stimulus that eventually comes to elicit a conditioned response

  • e.g. bell → salivation

unconditioned response

• the response associated with an unconditioned stimulus

conditioned response

• with enough pairings of the CS with a US, the CS will come to elicit the same response as the paired US

  • if CS + US is big enough, the CS will elicit a conditioned response

Association

• a relationship between two stimuli

  • US and CS

Acquisition

• the time period during which association is being learned

  • the amount of time it takes for a neutral stimuli to turn into a conditioned stimulus

what must occur in order for CC to be effective?

• the US must evoke a strong, bodily response

  • e.g. brain stimulation, drugs, loud noise, etc

• the more intense the US is, the easier it is to produce a CS

  • to a limit

US can be classified as … (2)

• appetitive: a stimulus that an individual finds pleasant

  • e.g. food

• aversive: a stimulus that an individual finds unpleasant

  • e.g. loud noise

types of CS - US pairings (4)

• forward short delay

• forward trace

• simultaneous

• backwards

forward short delay

• CS comes before the US

  • some overlap

• e.g. the bell rings before the food is presented

• most effective

forward trace

• CS comes first, short gap, then the US

  • no overlap

• e.g. bell rings → short pause → food presented

simultaneous

• CS and US presented at the same time

  • turn on and off at the same time

• learning is slower - acquisition is much slower

• e.g. bell and food presented at the same time

Backward

• US presented first and then the CS

• results in very little learning

• usually accidental

• e.g. food presented before the bell

enhancing acquisition: tips

• present multiple CS / US pairings

• aversive conditioning is learned faster than appetitive conditioning

  • e.g. this is how fears are created

• use forward pairings (CS → US)

• short interval between onset of CS with onset of US

ending an association is known as

• extinction

extinction

• accidental or purposeful

• a CS is presented in absence of US

• causes CR to weaken → disappear

spontaneous recovery

• if the CS is presented again following a delay after extinction, the CR reappears

  • but in weaker form

stimulus generalization

• once a CS has been established, similar stimuli may produce a CR

  • e.g. bit by one breed of dog - this fear extends to all breeds of dogs

• BUT the more similar the stimulus is to the old stimulus, the stronger the reaction

stimulus discrimination

• an organism learns to respond only to a specific conditioned stimulus (CS) and not to similar stimuli.

• non generalizable - CR occurs to one stimulus but no the other

• e.g. only being scared by big dogs, not little dogs

higher order conditioning

• a chain of events involving two CS

  • new neutral stimulus becomes a conditioned stimulus by being paired with an already established CS — not directly with the US.

• e.g. conditioning can occur without US!

example of higher order conditioning

1. first order (same as normal)

• US: food → UR: salivating

• CS: bell → CR: salivating

• eventually bell elicits salivation

2. second order

• present new neutral stimuli: light bulb

• pair lightbulb with the bell, NOT the food

• lightbulb elicits salivation

exposure therapy

• extinction of CR through exposure to CS

• without prescence of US

  • clinical setting

  • e.g. fear of snakes: presenting snakes over and over time, ensuring pain is not present. over time, the “pain” associated with snakes goes away

systematic desensitization

• muscular relaxation paired with gradual exposure to fear-inducing stimuli

flooding

• exposure to fearful stimuli

• “exposure therapy on steroids”

VR exposure therapy

• effective for phobias

Little Albert experiment

• little Albert was 11 months old

• shown a white rat, which was paired with a loud noise (gong)

  • eventually, became terrified of white rats

• he eventually generalized the stimuli to “soft and fuzzy” things

disgust

• disgust reactions are tied to stimuli that are biologically important to us

  • animals or objects that are dirty or dangerous

  • easily acquired!

operant conditioning

• learning controlled by the consequences of the organism’s behaviour

  • reward and punishment

  • AKA instrumental conditioning

order of operant conditioning

stimulus → response → reinforcer/feedback

the law of effect - discovered by who?

Edward thorndike

what is the law of effect

• if something good or satisfying happens after a response, there will be a stronger relationship between the stimulus and the response

  • satisfying: more

  • unsatisfying: yes

S-R theories of learning

• s: stimulus

• r: response

  • everything you do is a result of S-R bonds

puzzle boxes

• hungry cats placed in boxes with complicated escape routes (e.g. puzzles)

• milk or food placed outside of box, used as motivation

  • faster escape = quicker access to food

• first time, took longest for cat to find solution - but each subsequent performance improved

  • learning is incremental, NOT based on reasoning

BF Skinner

• created the Skinner box

  • AKA operant chamber

Skinner box

• electrically recorded animal’s activity

• automatically provides reinformcent in response to specific actions

  • if he completed the task, he gets rewarded with food

  • green light + push bar = rewarded

  • red light + push bar = not rewarded

reinforcement

• any outcome that strengthens the probability of a response

  • positive

  • negative

positive reinforcement

• reward

• the consequence consists of presenting something pleasant

• adding a stimulus

negative reinforcement

• punishment

• the consequence consists of removing something unpleasant

• removing a stimulus

increasing behaviour through ______

• reinforcement

• adding a stimulus

  • e.g studying for a test to get a good grade

decreasing behaviour through _____

• punishment

• removing a stimulus

  • e.g. removing a tantrum → give baby candy

punishment

• any outcome that weakens the probability of a response

  • positive

  • negative

positive punishment

• present an unpleasant stimulus

  • not studying for a test → receive a bad grade

negative punishment

• take away a pleasant stimulus

  • e.g. taking away phone time to focus on HW

reward does not mean _____?

• reinforcement

• e.g. using an umbrella - using an umbrella doesn’t make the rain stop

discriminative stimulus (S^d)

• any stimulus that signals the availability of reinforcement

  • e.g. cue light

  • e.g. Skinner box

    • when the light is green + push down on bar = rewarded

    • when the light is red + push down on bar = not rewarded

shaping

• reinforce succesive approximations towards a final response - shaping one action (pushing down on the bar)

  • 1. reward rat for facing the bar

  • 2. reward rat for approaching the bar

  • 3. reward rat for touching the bar

  • 4. reward rat for pushing down on bar

• must be able to do each task (step) successfully before moving to next step

chaining

• reinforce each response with the opportunity to perform the next response - builds a sequence of behaviours

  • e.g. now that the rat can push down on a bar, try having them push down on a button

  • 1. Go to lever

  • 2. Press lever

  • 3. Go to button

  • 4. Press button

continuous reinforcement

• being rewarded after every correct response

  • e.g. every time you do your chores, you get $5

partial reinforcement

• being rewarded after some correct responses

  • e.g. rewarding dog for “sitting” every couple times

fixed vs variable

• fixed: reinforcement after a fixed number of responses or interval of time

• variable: reinforcement after a variable (average) of responses or interval of time

ratio vs interval

• ratio: number of responses being reinforced

• interval: passage of time being that must elapse before being reinforced

fixed ratio

• reinforced after a fixed number of responses

fixed interval

• reinforced after a fixed amount of time

variable ratio

• reinforced after an average number of responses

variable interval

• reinforced after an average amount of time

best form of reinforcement?

• continuous

  • rapid learning

  • extinction more rapid

• partial

  • slower learning

  • resistant to extinction

• variable ratio is the best

  • avoids extinction

  • can’t predict when you will be rewarded (average)

escape and avoidance both based on _____?

• negative reinforcement (removing a stimulus to increase response)

escape behaviour

• getting away from something already happening

  • terminates aversive stimulus

• SRO

  • stimulus - shock

  • response - cross barrier

  • outcome - removal of shock

avoidance behaviour

• getting away from something before it happens

• SRO

  • stimulus - light (the rat moves to other side before shock occurs)

  • response - cross barrier

  • outcome - avoidance of shock

two process theory

• learning the avoidance response

  • 1. classical conditioning of a fear response to CS

    • associate light with shock

    • seeing light leads to fear

  • 2. operant conditioning of a escape response to fear evoking S^d

    • when the light turns on, rat runs over, avoids shock, reduces fear