Transcript Animal learning - Stanyer Stanyer

Animal learning
This part of the syllabus
• Simple learning (classical and operant conditioning) and its role in the
behaviour of non-human animals.
• What do you know
What is going to be covered
• Acquisition
• Extinction
• Spontaneous Recovery
• Disinhibition
• Generalization & Discrimination
• Higher-order conditioning & Preconditioning
Acquisition
• Acquisition: The gradual development and strengthening of a CR.
• The S-R association requires a number of pairings of the CS and US
before an CR develops.
• The more times the CS and US are paired, the stronger the CR.
• The stronger the US is and the stronger the NS is, the stronger and
faster conditioning will be.
• The strength of the CR will increase up to a certain point, and will
then level off. – For example, as a dog is repeatedly presented with a
tone and food, the amount of salivation increases until it reaches a
certain peak, at which point it will remain at that level.
Extinction
• Continually presenting a CS without a US, will result in the elimination
of the CR.
• When the CS no longer elicits a CR, experimental extinction is said to
have occurred. – Situations where it is useful to extinguish the CR?
Factors Affecting Extinction
• 1. The strength of the CR. The stronger the CSCR bond, the slower the
extinction of the CR.
• 2. Influence of Predictiveness: If the CS is occasionally presented
alone during acquisition, resistance to extinction is increased.
• 3. Exposure to Cs: As the duration of the CS exposure in extinction
increases, the strength of the CR weakens.
• Is the CR completely extinct? How can we tell?
Spontaneous Recovery
• The reappearance of the CR after a rest period following extinction.
• Becomes weaker each time it occurs after extinction
Does this remind
you of anything?
Spontaneous Recovery
To Pavlov, extinction is not a matter of “unlearning”, but of inhibiting
(suppressing) the CR. (still exists on some underlying level)
– Example: Imagine that you have a problem with test anxiety. Part way
through taking a test, your anxiety level starts to die down. Then,
someone walks into the test late and you experience a fresh wave of
anxiety.
Evidence for Pavlov’s View
• What causes this? Perhaps the process of disinhibition (the sudden
recovery of a response during an extinction procedure when a novel
stimulus is introduced).
• This shows that the CR is still right there, ready to return once your
“guard” is down – It also provides evidence for Pavlov’s view that
extinction is caused by inhibition rather than unlearning.
Classical Conditioning: A Refinement
• It is not very efficient to have to learn a separate conditioned
response to every single conditioned stimulus that is similar.
• At other times, it is important only to make the conditioned response
to a very particular stimulus.
• What are these processes called?
Generalization and Discrimination
• Examples of Stimulus Generalization
• Example: someone frightened at the sight of blood may transfer their
fear to other red objects.
• Little Albert -- conditioned fear of white rat that generalized to other
white fuzzy things
• Can lead to the onset of Phobias- Overgeneralization of fears to
inappropriate stimuli
Stimulus Discrimination
• Stimulus Discrimination: The tendency for a response to be elicited by
one stimulus and not another – – Example: baby learns that food
comes from its Mum (CS=Mum’s face) but not from any other person.
Second order conditioning
• Drill (US) - Whirring sound (NS) –- fear (UR)
• Haridryer NS2 - Whirring sound (CS) –- fear (CR)
• Haridryer CS2 –- fear (CR)
Outline key features of classical conditioning.
(8 marks)
Mark Scheme
• Features of Pavlovian classical conditioning include reflexive
unconditioned responses, such as salivation, to unconditioned stimuli
such as food; paired presentation of unconditioned neutral stimulus
(eg bell) with the unconditioned stimulus; development of the
conditioned response to the neutral stimulus. Other features such as
forwards/backwards conditioning, extinction, stimulus generalisation
and discrimination, and spontaneous recovery would also be relevant.
Note that for marks in the top band answers should be accurate and
well detailed. To move beyond Basic, in addition to an accurate
outline of the basic Pavlovian paradigm there should be reference to
one or more additional features.
Operant Conditioning
• What do you know!
Operant Conditoning
• Key Word is reinforcement
• There are four possible outcomes to behaviour:
• Positive reinforcement
• Negative reinforcement
• Positive Punishment
• Negative punishment
Positive reinforcement
• Positive reinforcement can also be called rewards. Rewards take on
many forms. For animals, one of the most common rewards is food.
Indeed, many behaviors animals do in the wild are for getting food. If
certain behaviors allow an animal to get food successfully, the animal
will repeat these behaviors the next time it is hungry.
• Food is an example of a primary reinforcer. Primary reinforcers are
reinforcers that are automatically positive. An animal does not have
to learn to "like" them. Other examples of primary reinforcers include
water, shelter, and mating opportunities. Several types of primary
reinforcers provide tactile stimulation, like a good back scratch. For
people, a hug can be very reinforcing.
Negative reinforcement
• Negative reinforcement is not punishment. Punishment involves giving an
unfavourable consequence. Punishment decreases the likelihood of a behavior
repeating. Both positive and negative reinforcement increase the likelihood that a
behaviour will be repeated.
• Almost all traditional animal training consists of the applied use of negative
reinforces. The horse learns to turn left when the left rein is pulled, because by
doing so it can ameliorate the tugging feeling in the left corner of it's mouth.
Elephants, oxen, camels, and other beasts of burden learn to move forward, halt,
pull loads, and so on to avoid the tug of a halter, the poke or blow of a prod,
goad, or whip.
• People use spontaneous negative reinforcers on each other all the time: The
warning glance, the frown, the disapproving remark. Some children's lives, and
some spouses' lives too, are filled with constant daily effort to behave in such a
way as to avoid disapproval.
• If this is not good enough use baby crying - parents remove crying.
Positive Punishment
• Positive punishment is something that is applied to reduce a behaviour. The term
"positive" often confuses people, because in common terms "positive" means something
good, upbeat, happy, pleasant, rewarding. Remember, this is technical terminology we're
using, though, so here "positive" means "added" or "started". Also keep in mind that in
these terms, it is not the animal that is "punished" (treated badly to pay for some moral
wrong), but the behaviour that is "punished" (in other words, reduced). Positive
punishment, when applied correctly, is the most effective way to stop unwanted
behaviours. Its main flaw is that it does not teach specific alternative behaviours.
Examples
• Our society seems to have a great fondness for positive punishment, in spite of all the
problems associated with it. The peeing on the rug (by a puppy) is punished with a swat
of the newspaper. A dog's barking is punished with a startling squirt of citronella. The
driver's speeding results in a ticket and a fine. The baby's hand is burned when she
touches the hot stove. Walking straight through low doorways is punished with a bonk
on the head. In all of these cases, the consequence (the positive punishment) reduces
the behaviour's future occurrences.
Negative punishment
• Negative punishment is reducing behaviour by taking away Something Good. If the
animal was enjoying or depending on Something Good she will work to avoid it getting
taken away. They are less likely to repeat a behaviour that results in the loss of a Good
Thing. This type of consequence is a little harder to control.
Examples
• The child has his crayons taken away for fighting with his sister. The window looking into
the other monkey's enclosure is shut when the first monkey bites the trainer. "This car
isn't getting any closer to Disneyland while you kids are fighting!" The dog is put on leash
and taken from the park for coming to the owner when the owner called (this causes the
unintentional result of the dog being less likely to respond to the recall). The teenager is
grounded for misbehaviour. The dolphin trainer walks away with the fish bucket when
the dolphin acts aggressive. "I'm not talking to you after what you did!" Xena The
Warrior Princess cuts off the air of an opponent who refuses to tell her what she wants.
In short
• Positive reinforcement: receiving something pleasant.
• Negative reinforcement: not receiving something unpleasant.
• Positive Punishment: receiving something unpleasant.
• Negative punishment: not receiving something pleasant.
Primary and secondary
• Primary occur naturally and directly satisfy biological needs. Eg: food
• Secondary where they have to be learned and indirectly satisfy
biological need eg: money.
Behaviour Shaping
• Using operant conditioning to gain a desired outcome through
reinforcement.
• B. F. Skinner used shaping—a method of training by which successive approximations toward a target behaviour are
reinforced—to test his theories of behavioural psychology.
• Shaping involves a calculated reinforcement of a "target behaviour": it uses operant conditioning principles to train a
subject by rewarding proper behaviour and discouraging improper behaviour.
• The method requires that the subject perform behaviours that at first merely resemble the target behaviour; through
reinforcement, these behaviours are gradually changed or "shaped" to encourage the target behaviour itself.
• Skinner's early experiments in operant conditioning involved the shaping of rats' behaviour so they learned to press a
lever and receive a food reward.
• Shaping is commonly used to train animals, such as dogs, to perform difficult tasks; it is also a useful learning tool for
modifying human behaviour.
Source: Boundless. “Shaping.” Boundless Psychology. Boundless, 20 Aug. 2015. Retrieved 15 Sep. 2015 from
https://www.boundless.com/psychology/textbooks/boundless-psychology-textbook/learning-7/operant-conditioning47/shaping-198-12733/
Reinforcement Schedules
• Fixed Ratio
• Fixed Interval
• Variable ratio
• Variable interval
• Watch this
Role of learning in Non-human animals
• Learn whether food sources are safe.
• Biological Preparedness: Is the animal predisposition to learn.
• Trial and error is used often with operant conditioning
Research
• Skinner: rats and doves
• Baker trial and error learning by pigeons to discover navigational aids.
• Fisher and Hinde showed that animals learn behaviours similar to
innate ones. Blue tits stripping the tops off milk similar to stripping
bark off trees.
Evaluation
• Social learning also occurs through observation and imitation
• Does not account for innate influences such as biological
preparedness or instinctive drift.
• Behaviourism sees no role for free will.
• Unethical training animals for warfare.
• Emotional and cognitive factors eg: insight learning by chimps
The Ecological Perspective
• Skinner’s view was that virtually any response can be conditioned in any
stimulus situation—this is known as equipotentiality. In fact, this is not
true. Some behaviours are harder to learn than others and even harder to
maintain because of “instinctive drift”, i.e. the preference for a behaviour
that is instinctive may replace or modify the conditioned behaviour. This is
shown in research by Gaffan, Hansel, and Smith (1983) in which rats in a Tshaped maze had to decide whether to turn left or right. According to
conditioning, if the rat was rewarded for turning left it should turn left on
the following trial. However, in the natural environment the rat would not
return to where it had just removed food. Gaffan et al. found that early in
training rats tended to avoid the arm of the maze in which they had
previously found food, as predicted from the ecological perspective. This
shows the influence of their instinctive behaviour.
EVALUATION OF OPERANT CONDITIONING
Applications. The principles of operant conditioning (OC) have been used
effectively in the training of animals and this has generated many positive
applications. For example, OC has been used to teach language to chimps,
and the learning process involved has informed understanding of children
who have learning difficulties. Thus, OC has made significant contributions
both theoretically and in applied psychology.
Equipotentiality lacks validity. Skinner’s concept of equipotentiality is
incorrect, as is his assumption that operant conditioning is uninfluenced by
instinctive behaviour, as instinctive drift shows animals have a preference for
instinctive behaviour.
Circularity. We only know that a stimulus is a reinforcer because it
reinforces! It is not a scientific statement, because there is no way that it can
be tested. This means the concept of reinforcement is circular and lacks
scientific validity.
Individual differences. Food is a fairly universal source of reinforcement for
animals—all animals need food! However, other forms of reinforcement may have
a less consistent effect, as whether the reinforcement is rewarding or punishing is
open to interpretation.
Ignores other forms of learning. Other forms of learning are possible. Humans
often engage in observational learning—they learn simply by observing someone
else being rewarded for behaving in a certain way. Operant conditioning does not
account for the more sophisticated social learning.
Ignores nature. Skinner exaggerated the importance of external or environmental
factors as influences on behaviour and minimised the role of internal factors. For
example, apes have innate personalities and instinctive behaviours.
Difficult to distinguish between CC and OC. A key problem is that it can be difficult
to distinguish between CC and OC in the learning process. For example, if we take
Pavlov’s research, was the food the UCS or was it a source of positive
reinforcement?
Scientific validity. The research on OC is conducted in the controlled
conditions of the laboratory and so it can be replicated to check reliability
and has greater control of confounding variables and so higher internal
validity.
External validity. Research in the laboratory is artificial, e.g. rats pressing a
lever, dogs salivating to a bell, and so it is difficult to know how well the
theory generalises to real-life animal behaviour. The simple conditioning
researched in the laboratory is much more complex in real life.
Ignores cognitive factors. The rejection of the influence of cognition
(because this is not observable or measurable) is a key limitation of OC as
animals are capable of developing expectancies that a particular form of
reinforcement will follow a behaviour. This is a significant omission since
cognitive factors are an important part of the learning process.
Instinctive drift
Instinctive drift or instinctual drift is the tendency of an animal to
revert to instinctive behaviours that interfere with
a conditioned response. The concept originated with B.F. Skinner's
former students Keller Breland and Marian Breland when they tried to
teach a raccoon to put tokens into a piggy bank. Instead, the raccoon
drifted to its instinctive behaviour of putting the tokens on the ground
or turning them over in its paws, as they often do with food.
Notes handout and essay question.