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

Australopithecus afarensis (400cc), Homo erectus (1200cc), Homo sapiens (1400cc)

• Skull• Bipedalism

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

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

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

muscle

sensoryneuron

interneuron

motorneuron

?

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

heatsource

testing arena

Kinesis• Movement in a random direction

hot

cool

medium fastslow

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

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 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

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