Learning and Behaviour Learning –Enduring change in behaviour –Due to experience –How something is done Behaviour –Procedures and actions performed –Learning.
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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
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
Australopithecus afarensis (400cc), Homo erectus (1200cc), Homo sapiens (1400cc)
• Skull• Bipedalism
Examples: Behavioural Evolution
• Cooperation (e.g., food sharing, child rearing)
• Pair bonding
• Altruism
Control System
• Comparator
• Reference input
• Actual input
• Action system
• Output
• Feedback system (closed-loop system)
• Response lag
Blood Salinity
Comparator
Output
Eat peanuts!
Action System
Actual input
Eat more peanuts!Drink water!
Reference input
Reflexes
• Stereotypic movement patterns
• Reliably elicited by appropriate stimulus
• Survival benefit
Types of Tropisms
• Kinesis– Movement random with respect to stimulus
• Taxis– Non-random (directed) movement with respect
to stimulus
Taxis• Movement that bears some relationship to
the location of a stimulus
testing arena heatsourcehot
cool
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 / Biosphotowww.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=ot2www2CF3Y
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 re-extended
Results
• Slug eyestalk re-extension times– Trial 1: 23 sec
– Trial 2: 12 sec
– Trial 3: 10 sec
– Trial 4: 7 sec
– Trial 5: 3 sec
– Trial 6: 1 sec
25
12.5
Trial
1 2 3 4 5 6
Tim
e (s
ec.)
Example: Rat Sensitization
• 1. Gentle touch, no response
• 2. Painful shock, flinch
• 3. Gentle touch, flinch
Habituation Sensitization
Generalization Less More
Length of effect Longer Shorter
Rate of relearning
Quicker than initially
Quicker than initially
Habituation and Sensitization
• 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
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