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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
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Types of Learning Habituation/sensitization Classical conditioning Operant conditioning Observational/vicarious
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Adaptation Changing conditions Time scales Learning only one type of adaptation
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Innate Behaviours
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Evolved Environmental change Re: Learning –Roots in innate behaviours –Parallels Homeostasis, reflexes, tropisms, modal (fixed) action patterns
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Evolutionary Theory Voyage of the Beagle (1831-1836) On the Origin of Species (1859) Artificial, natural, and sexual selection Adaptation to environment
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Natural Selection Variation, inheritance, selection Differential reproductive success No intelligent design Level of the individual Change over generations
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Examples: Physical Evolution Australopithecus afarensis (400cc), Homo erectus (1200cc), Homo sapiens (1400cc ) Skull Bipedalism
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Examples: Behavioural Evolution Cooperation (e.g., food sharing, child rearing) Pair bonding Altruism
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Homeostasis Internal balance of the body Drives Regulatory drives
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Control System Comparator Reference input Actual input Action system Output Feedback system (closed-loop system) Response lag
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Blood Salinity Comparator Output Eat peanuts! Action System Actual input Eat more peanuts! Drink water! Reference input
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Reflexes Stereotypic movement patterns Reliably elicited by appropriate stimulus Survival benefit
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Example: Grasping in Infants Humans, other primates
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Example: Eyeblink Stimulus (e.g., airpuff) Eyelid closes
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Example: Limb Retraction Sharp rock, hot surface, etc. Fast muscle contraction Pulls limb away
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Reflexes Rapid response Simple neural pathways Sensory neuron, interneuron, motor neuron
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Reflex Arc muscle sensory neuron interneuron motor neuron ?
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Tropisms Movement, or change in direction, of the entire animal Jacque Loeb –Geotropism
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Geotropism
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Types of Tropisms Kinesis –Movement random with respect to stimulus Taxis –Non-random (directed) movement with respect to stimulus
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heat source testing arena Kinesis Movement in a random direction hot cool mediumfast slow
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Taxis Movement that bears some relationship to the location of a stimulus testing arena heat source hot cool
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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
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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
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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-ByPkUhttp://www.youtube.com/ watch?v=vUNZv-ByPkU www.cerebromente.org.br/n09/fastfacts/comportold_I.htm
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Stickleback Bruno Cavignaux / Biosphoto www.arkive.org/three-spined-stickleback/ gasterosteus-aculeatus-aculeatus/image-A23078.html http://www.mylot.com/w/image/1967361.aspx
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Supernormal Stimuli Extreme version of sign stimulus Size, colouration, etc. Preference sometimes detrimental
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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
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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
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Environmental Interaction Not strictly genetically controlled Susceptible to conditioning e.g., twin studies
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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 2CF3Yhttp://www.youtube.com/watch?v=ot2www 2CF3Y
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Habituation and Sensitization Simplest form of Learning
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Habituation and Sensitization Changes reflex response Learning without new axons/synapses Temporary effect at existing synapse –E.g., less neurotransmitter released from axon terminal
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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
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Example: Banana Slug Habituation Eyestalk retraction Touch back Record time until eyestalks are fully re- extended
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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 123456 Time (sec.)
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Example: Rat Sensitization 1. Gentle touch, no response 2. Painful shock, flinch 3. Gentle touch, flinch
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HabituationSensitization GeneralizationLessMore Length of effectLongerShorter Rate of relearning Quicker than initially Habituation and Sensitization Generalization: treat other stimuli like learned stimuli Discrimination: distinguish other stimuli from learned stimuli
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Spontaneous Recovery Post habituation or sensitization Return to original level of responding Due to passage of time
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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
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Learning: Evolved Modifiability Selective pressure Learning –Going beyond innate behaviour patterns All animals Evolutionarily selected for Allows individuals to adapt to rapid environmental change
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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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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
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