Transcript PowerPoint slides

Learning and Behaviour
• Learning
– Enduring change in
behaviour
– Due to experience
– How something is
done
• Behaviour
– Procedures and
actions performed
– Learning
– Non-learning
– What is done
Types of Learning
•
•
•
•
Habituation/sensitization
Classical conditioning
Operant conditioning
Observational/vicarious
Adaptation
• Changing conditions
• Time scales
• Learning only one type of adaptation
Innate Behaviours
Innate Behaviours
• Evolved
• Environmental change
• Re: Learning
– Roots in innate behaviours
– Parallels
• Homeostasis, reflexes, tropisms, modal (fixed)
action patterns
Evolutionary Theory
• Voyage of the Beagle
(1831-1836)
• On the Origin of
Species (1859)
• Artificial, natural, and
sexual selection
• Adaptation to
environment
Natural Selection
•
•
•
•
•
Variation, inheritance, selection
Differential reproductive success
No intelligent design
Level of the individual
Change over generations
Examples: Physical Evolution
• Skull
• Bipedalism
Australopithecus afarensis (400cc), Homo erectus
(1200cc), Homo sapiens (1400cc)
Examples: Behavioural Evolution
• Cooperation (e.g., food sharing, child
rearing)
• Pair bonding
• Altruism
Homeostasis
• Internal balance of the body
• Drives
• Regulatory drives
Control System
•
•
•
•
•
•
•
Comparator
Reference input
Actual input
Action system
Output
Feedback system (closed-loop system)
Response lag
Blood Salinity
Comparator
Reference input
Output
Actual input
Action System
EatEat
more
peanuts!
Drink
water!
peanuts!
Reflexes
• Stereotypic movement patterns
• Reliably elicited by appropriate stimulus
• Survival benefit
Example: Grasping in Infants
• Humans, other primates
Example: Eyeblink
• Stimulus (e.g., airpuff)
• Eyelid closes
Example: Limb Retraction
• Sharp rock, hot
surface, etc.
• Fast muscle
contraction
• Pulls limb away
Reflexes
• Rapid response
• Simple neural pathways
• Sensory neuron, interneuron, motor neuron
Reflex Arc
sensory
neuron
interneuron
muscle
motor
neuron
?
Tropisms
• Movement, or change in direction, of the
entire animal
• Jacque Loeb
– Geotropism
Geotropism
Types of Tropisms
• Kinesis
– Movement random with respect to stimulus
• Taxis
– Non-random (directed) movement with respect
to stimulus
Kinesis
• Movement in a random direction
testing arena
hot
slow
cool
medium
fast
heat
source
Taxis
• Movement that bears some relationship to
the location of a stimulus
testing arena
hot
cool
heat
source
The Models
• Kinesis
–
–
–
–
Random turn
Set move length
No more than 180° turn
Movement speed variable (fast, medium, slow)
• Taxis
–
–
–
–
Turn so as to move away from heat
Set move length
No more than 180° turn
Movement speed fixed
Modal (Fixed) Action Patterns
• Originally “fixed”; variable to some degree
• Species specific, often state dependent
• Sign stimulus (“releaser”) activates a
dedicated neural system
• To completion in sequence
Graylag Goose
• Rolls displaced egg near
its nest back with beak
• Sign stimulus: displaced
egg
• Remove egg during
sequence
• http://www.youtube.com/
watch?v=vUNZv-ByPkU
www.cerebromente.org.br/n09/fastfacts/comportold_I.htm
Stickleback
Bruno Cavignaux / Biosphoto
www.arkive.org/three-spined-stickleback/
gasterosteus-aculeatus-aculeatus/image-A23078.html
http://www.mylot.com/w/image/1967361.aspx
Supernormal Stimuli
• Extreme version of sign stimulus
• Size, colouration, etc.
• Preference sometimes detrimental
Beetles on the Bottle
• Gwynne & Rentz
(1983)
• Male Jewel beetles
(Julodimorpha
bakewelli)
• Colour and reflection
of bumps on bottle as
supernormal stimuli for
female beetle
General Behaviour Traits
• Behavioural traits strongly influenced by
genes
• Not the same as Modal Action Patterns
– GBTs more plastic than MAPs
– No single sign stimulus
• e.g., Species Specific Defense Reactions
– Freeze, flee, fight
– Mouse vs. bear
Environmental Interaction
• Not strictly genetically controlled
• Susceptible to conditioning
• e.g., twin studies
Behavioural Influence
•
•
•
•
•
Selective breeding studies
Artificial or natural selection
e.g., morphine addiction in rats
e.g., Silver foxes
http://www.youtube.com/watch?v=ot2www
2CF3Y
Habituation and Sensitization
Simplest form of Learning
Habituation and Sensitization
• Changes reflex response
• Learning without new axons/synapses
• Temporary effect at existing synapse
– E.g., less neurotransmitter released from axon
terminal
Habituation
• Decease in a response following repeated
stimulus presentation
• Note: note everything that results in a
decrease in response is habituation
Sensitization
• Increase in a response following repeated
stimulus presentation
Example: Banana Slug
Habituation
• Eyestalk retraction
• Touch back
• Record time until
eyestalks are fully reextended
Results
• Slug eyestalk
re-extension times
– Trial 1: 23 sec
– Trial 2: 12 sec
– Trial 3: 10 sec
Time (sec.)
– Trial 4: 7 sec
– Trial 5: 3 sec
– Trial 6: 1 sec
25
12.5
1
2
3
Trial
4
5
6
Example: Rat Sensitization
• 1. Gentle touch, no response
• 2. Painful shock, flinch
• 3. Gentle touch, flinch
Habituation and Sensitization
Habituation
Sensitization
Generalization
Less
More
Length of effect
Longer
Shorter
Rate of
relearning
Quicker than Quicker than
initially
initially
• Generalization: treat other stimuli like learned stimuli
• Discrimination: distinguish other stimuli from learned stimuli
Spontaneous Recovery
• Post habituation or sensitization
• Return to original level of responding
• Due to passage of time
Limits of Natural Selection
• Adaptation relatively slow
• Generally not helpful during a lifetime
• Select best adapted individuals from each
generation
• Evolutionary time lag
• Variation within species
Learning: Evolved Modifiability
• Selective pressure
• Learning
– Going beyond innate behaviour patterns
• All animals
• Evolutionarily selected for
• Allows individuals to adapt to rapid
environmental change
Nature and Nurture
•
•
•
•
•
Long debate
British Empiricists vs. Nativists
Not “either/or,” but “both”
Genes and environment constantly interact
Biology and experience both shape an
organism’s behaviour patterns
The Ability to Learn
• A by-product of both
heredity and
experience
• e.g., rats reared in
complex
environments
• e.g., educational aids
for infants