Human and Animal Learning and Behavior
Overview of Human and Animal Learning and Behavior
Behavior: Any outward or inward response to a stimulus.
Includes actions, speech/language, feelings, and thoughts.
Elicited by a stimulus, seen or unseen, conscious or unconscious.
Causes of Changes in Behavior
Two main sources:
Nature: Evolution
Nurture: Learning
Evolution
Darwin's Theory of Evolution:
Populations can increase exponentially if resources are sufficient.
Resources are limited.
Competition for resources leads to a struggle amongst individuals.
Variability exists within a species due to genetic mutations or random chance.
Variability is heritable.
Individuals with advantageous traits adapt better, reproduce more, and pass on their genes more frequently.
Learning & Experience
Learning:
An enduring change in the mechanisms of behavior based on prior experience.
Can occur consciously or unconsciously.
Can occur with or without immediate changes to behaviour.
Classified as either associative or non-associative.
Often stimulus- and response-specific.
Understanding the relationship between learning and behavior allows us to better predict and modulate human behavior.
Works in combination with evolutionary adaptations.
Interaction of Evolution and Learning
Evolution interacts with learning to produce changes in behavior.
Lifespan and environment stability determine whether behavior is largely influenced by evolution or learning.
Evolution-Dominant Behaviors
Reflexes
Single response.
Occur in direct response to a stimulus.
Non-associative.
In vertebrates, simple reflexes are mediated by the reflex arc (sensory neuron + the interneuron + motor neuron).
Reflex Arc
Components:
Sensory receptor in skin
Afferent pathway
Integrating center
Efferent pathway
Effector organs
Adaptive Significance of Reflexes
Adaptive, especially when learning the response may be costly.
Examples: infant suckling, orienting towards loud noise or lights
Reflexes vs. Modal Action Patterns (MAPs)
Reflexes:
Single action.
Modal action patterns:
Response sequences that are typical of a particular species.
Examples: mating/courtship rituals, defensive action patterns.
Modal Action Patterns (MAPs)
Include instinctive activities, but these behaviours can be modified by experience and environment.
Variable – MAPs not strictly fixed (hence the use of the word modal instead of fixed, now).
They vary slightly and the threshold for eliciting such activities varies.
Stimulus-specific – MAPs are only activated in the presence of particular stimuli.
The same stimulus can have different effects depending on the physiological state of the animal and its recent actions.
Examples: defensive action pattern and proximity of threat.
Eliciting MAPs
Sign stimulus (releasing stimulus): Responsible for activating a MAP.
Can be a combination of stimuli.
Supernormal stimulus: An exaggerated sign stimulus that elicits an especially vigorous response.
Functions of MAPs
Defensive MAPs are critical for survival.
Evident in readiness to fear evolutionarily threatening stimuli.
Social and sexual behaviour
Cosmetics and perfumes take advantage of MAPs elicited by visual and olfactory sign stimuli.
Components of MAPs
Early components of sequence: Appetitive behaviour
Can take a variety of forms and can even vary in sequence.
More affected by learning.
Final components of sequence: Consummatory behaviour
Highly stereotyped species typical behaviours.
Have specific eliciting or releasing stimuli.
Examples: building a nest and mating, nighttime ritual and sleeping.
Example: Foraging Sequence (W. Timberlake)
General search mode
Not spatially localised
Focal search mode
Spatial specificity
Food handling and ingestion mode
Consummatory behaviour
Changes in Behaviour from Experience
Responses are never uniform, even with simple reflexes.
Experiences can change behavior.
Experiences may be directly experienced or observed.
Repeated Stimulation
Repeatedly experiencing the same stimulus has two effects:
Habituation: Decline in responding
Sensitisation: Increase in responding
These changes are considered non-associative learning.
Examples of Habituation
Startle response
Part of an organism’s defensive reaction to potential or actual threat.
Used to study fear and learning.
Generally studied with rats, mice, rabbits, humans using loud tones or bright lights.
Salivation and hedonic ratings
Stimulus specific.
Affected by attention.
Relevant for controlling eating behavior.
Facial recognition by infants
Habituated to familiar face
Showed preferential and longer viewing time of novel face than familiar face, even when they were presented at different orientations.
Factors Affecting Habituation
With the same stimulus exposure at each presentation, habituation will occur more rapidly with shorter interstimulus intervals.
With the same number of presentations and interstimulus interval, habituation will occur more rapidly if the stimulus is presented for longer periods at each presentation.
With the same interstimulus interval and duration, habituation will occur more rapidly if the stimulus is presented more.
Characteristics of Habituation
Habituation is stimulus specific.
Presenting a different stimulus should result in a recovery (dishabituation) of the response.
Presenting a different stimulus can also cause dishabituation, in which the response to the original stimulus returns.
Spontaneous recovery of the response will occur if a retention interval is imposed.
Sensitization
Increased response due to increased level of arousal.
Arousal intensifies appetitive and aversive experiences.
The increased response occurs to the original and other stimuli.
Key Differences Between Habituation and Sensitization
Habituation
Decline in responding
Stimulus-specific
Long-term and short-term effects
Common
Sensitisation
Increase in responding
Not highly stimulus specific
Generally, only short-term effects
Less common
Other Examples of Sensitization
Concerts
Sexual behaviour
Defensive behavioural system
Eyeblink response
Baseline Response
Relationship between sensitization, habituation, desensitization, and dishabituation.
Adaptive Significance of Habituation and Sensitization
Help organism distinguish between stimuli that should be ignored and stimuli that should be attended to.
Underlying Processes of Habituation and Sensitization
Dual-Process Theory (Groves & Thompson, 1970)
Addresses underlying factors responsible for behavioural habituation and sensitisation.
Note that this theory separates underlying processes from outward behavioural changes.
Assumes that different types of underlying neural processes are responsible for increases and decreases in responsiveness.
Habituation process
Sensitisation process
Not mutually exclusive.
Behavioural output depends on relative strength of process.
Thus, habituation and sensitisation effects are both due to habituation and sensitisation processes with the sum determining outward behaviour.
Neural Substrates
Habituation processes occur in the S-R system, the reflex arc.
Each presentation of an eliciting stimulus activates the S-R system and causes buildup of habituation.
Sensitisation processes occur in the state system.
The state system consists of other parts of the nervous system that determine the organism’s general level of responsiveness or readiness to respond.
The state system is activated only by arousing events.
Can be affected by external influences, such as drugs or fear
Dynamics
The S-R system is activated every time a stimulus elicits a response.
The state system becomes involved only when there is an arousing event.
Both processes decay over time without further stimulation, resulting in spontaneous recovery from both processes to baseline levels.
Different S-R circuits for different eliciting stimuli account for why habituation is stimulus specific (e.g., sensory receptors for repeated punching in arm followed by pin prick).
State system is not stimulus specific, although there appear to be different systems for external pain and internal malaise.
Important contribution of the theory has been the assumption that elicited behaviour can be strongly influenced by neurophysiological events that take place outside the reflex arc that is directly involved in a particular elicited response.
Emotions and Motivated Behaviour
In addition to elicited external responses, stimuli can also evoke complex emotions.
Concepts of habituation and sensitisation have been extended to changes in emotions and various forms of motivated behaviour (e.g., feeding, exploration, aggression).
Drug addictions are an area of particular interest.
Solomon & Corbit (1974)
Intense emotional reactions are often biphasic.
One emotion occurs during the elicited stimulus, and the opposite emotion is observed when the stimulus is terminated.
Like basic behaviours that change after repeated stimulation, emotional reactions change with experience.
The primary reaction becomes weaker, and the after-reaction becomes stronger.
Habituation = drug tolerance
Drinking, narcotic drugs
Extended to other emotion arousing stimuli, e.g., love and attachment.
Opponent Process Theory
Opponent process theory assumes that emotions are directly related to neurophysiological mechanisms, which try to maintain homeostasis.
External behaviour is the net result of the direct effects of an emotion arousing stimulus which activates a primary process and the opponent process that is activated to counteract this direct effect.
Processes
Primary process (a process): Responsible for the quality of the emotional state that occurs in presence of the stimulus.
Opponent process (b process): Generates the opposite emotional reaction.
Lags behind primary emotional disturbance.
Dynamics After Extensive Stimulus Exposure
Primary reaction becomes weaker; after- reaction becomes stronger.
Importantly, just like with the Dual-Process Theory, the two hypothesised underlying a and b processes of the Opponent-Process theory are distinct from the outward behaviour that is observed.
Behaviour is a manifestation of the underlying opponent processes.
Application to Addiction
Frequent users do not experience great highs.
Why continue using?
Addictions are an attempt to reduce the aversiveness of the affective after-reaction to the drugs.
“hair of the dog”
“addicted drug users sustain their drug use largely to manage their misery” –Baker et al., 2004
Supported by neurophysiological studies showing reduced activation in reward circuit and increased activation in the anti-reward circuit.
Conditioned Drug Tolerance
A form of associative learning
Stimulus cues get paired with stimulus effects
Stimulus cues = conditioned stimulus (CS)
Stimulus effects = unconditioned stimulus (US)
Natural response to the stimulus = unconditioned response (UR)
After repeated CS to US pairings (i.e., CS-US), the B response activates upon presentation of the CS alone
The B process is the body’s attempt to maintain homeostasis in anticipation of the UR upon gaining the US
Tolerance to the stimulus forms as a result, requiring more of the stimulus to achieve initial UR levels
The learned association can be interrupted by inserting novel stimuli, such as a change in environment
Novel stimuli, however, can disrupt the body’s attempt at homeostasis, resulting in an overdose
Summary
Behaviour includes everything from a simple reflex mediated by just three neurons to complex emotions that involve whole systems and processes.
Behaviour occurs in response to an eliciting stimulus.
Behaviour varies according to the surrounding circumstances.
It may not occur if the conditions are not right; it can decrease or increase if the eliciting stimulus is presented repeatedly.
Your behaviour is the product of your genes, your experience, and learning.
Complex emotional reactions are changed after repeated stimulation according to the opponent process theory.