Chapter Three

Innate Behaviours

• Nativism
• Evolutionarily adapted behaviour
• Roots of learned behaviour
• Parallels with learned behaviours

Divisions of Study

Ethology

• European
• Zoological
• Naturalistic observations
• Adaptive behaviours
• Fixed (modal) action patterns
• Neuroethology and computational ethology

Comparative Psychology

• North American
• Psychology (human)
• Experimental research
• General-processes approach

General-Process Approach

• Diversity…focus on similarities

 

• Underlying elemental mechanisms

 

• Rules of learning

Comparative Cognition

• Recent
• Merges ethology and comparative psychology
• Cross-species comparison
• Cognitive processes
• Not focussed on human explanations

Evolutionary Psychology

• Very recent
• Evolutionary explanations of behaviour?
• Merging of behavioural ecology, sociobiology, cognitive and behavioural psychology

Innate Behavioural Systems

Why Study Innate Behaviours?

• Evolved
• Learned behaviours have roots in innate behaviours
• Parallels between learned and innate behaviours
• Some innate behaviours modifiable

Homeostasis

• Internal balance of the body
• Drives
• Regulatory drives

(Figure 1)

Control System

• Comparator
• Reference input
• Actual input
• Action system
• Output
• Feedback system (closed-loop system)

Reflexes

• Stereotypic movement
• Elicited by appropriate stimulus
• Innate and evolved

Example: Grasping in Infants

• Humans, other primates

(Figure 2)

Reflex Action

• Spinal animals
• Threshold
• Latency
• Irradiation

Principles of Reflex Action (Sherrington)

• Spinal animals (dogs)
• Threshold, latency, irradiation

(Figure 3)

Control System in Reflex Arc

• Actual input: pin prick
• Reference input: pain threshold
• Comparator: actual input to reference input
• Output: motor neuron action potentials
• Action system: retracting limb

Tropisms and Orientation

• Tropism:
• Movement, or change in direction, of the entire animal

Loeb and Geotropism

(Figure 4)

Geotropism

(Figure 5)

Kinesis

• Movement in a random direction

(Figure 6)

Taxis

• Movement that bears some relationship to the location of a stimulus

(Figure 7)

Fixed (Modal) Action Patterns

• Sequences of behaviour
• Present in all members of the species
• Innate
• Ordered

Example: Gull Chicks

(Figure 8)

Sign Stimulus

• Stimulus that elicits a fixed action pattern

(Figure 9)

Example: Sign Stimulus in Stickleback

(Figure 10)

Example: Stickleback

• Stimuli that cause aggressive behaviour in males

(Figure 11)

Example: Waterstrider Mating

(Figure 12)

Reaction Chains

• Initiated by a particular stimulus
• Progression condition dependent
• Starts with most appropriate behaviour in chain
• Can end before chain complete

Habituation and Sensitization

Simplest form of Learning

Habituation

• Decrease in a response following repeated stimulus presentation

Sensitization

• Increase in a response following repeated stimulus presentation

Banana Slug Habituation

• Eyestalk retraction
• Touch back
• Record time until eyestalks are fully re-extended

(Figure 13)

Results

• Slug eyestalk re-extension times

(Figure 14)

Characteristics of Habituation and Sensitization

• Time course
• Habituation
• Short-term

 

• Long-term
• Sensitization
• Short-term
• Intensity --> Sensitivity

• Specificity and generalization
• Habituation

 

• Sensitization

 

• Overlearning
• Dishabituation
• Reverse habituation by sensitization to extraneous stimulus

Physiological Mechanisms of Habituation

• Neurologically simple
• Seen across species
• Example: Aplysia

(Figure 15)

Aplysia Gill-Withdrawal Reflex

(Figure 16)

Synaptic Effects of Habituation

• Decrease in excitatory conductance
• No change in postsynaptic sensitivity
• Reduced neurotransmitter release
• Decrease in active zones

Neurochemical Level: Calcium

(Figure 17)

Learning Through Habituation

• Learning without new axons/synapses
• Chemical change at synapse
• Plasticity

Opponent-Process Theory: Emotional Response

• Present emotion-arousing stimulus
• Peak reaction
• Adaptation phase
• Steady state
• Remove stimulus
• Affective after-reaction
• Baseline state

(Figure 18)

• Homeostatic theory
• Processes
• Primary (a):

 

• Opponent (b):

(Figure 19)