Understanding the patterns of behaviour is crucial in biology and psychology. Behaviours can be broadly categorized into those that are innate and largely fixed, and those that are acquired or modified through experience. This unit will delve into various behavioural patterns, from simple reflexes to complex learned responses.
1. Stereotyped Behaviours and Individual Behavioural Patterns
Stereotyped Behaviours
Stereotyped behaviours are predictable, invariant, and often genetically pre-programmed sequences of actions that are characteristic of a species. They are typically performed in response to specific stimuli and are largely resistant to modification through learning. These behaviours are also known as Fixed Action Patterns (FAPs).
Definition: Stereotyped behaviours are highly predictable and rigid sequences of actions, often innate, that are performed in a consistent manner by members of a species in response to specific cues.
Key Characteristics:
- Innate: Generally present from birth or develop without prior learning.
- Species-specific: Common to almost all members of a species.
- Highly rigid: Follow a fixed, unchangeable sequence once initiated.
- Triggered by releasers: Initiated by specific external stimuli known as 'releasers' or 'sign stimuli'.
Orientation
Orientation refers to the ability of an organism to position itself or its body parts in relation to environmental cues. It is a fundamental stereotyped behaviour that helps organisms navigate, find food, avoid predators, and reproduce.
Definition: Orientation is the process by which an organism adjusts its position or movement in space relative to an environmental stimulus.
Examples of Orientation:
- Taxes: Directed movements towards (positive taxis) or away from (negative taxis) a stimulus (e.g., phototaxis towards light, chemotaxis towards chemicals).
- Kineses: Undirected movements in response to a stimulus, where the rate of movement or turning changes with stimulus intensity (e.g., woodlice moving faster in dry areas until they find a moist one).
Reflexes
A reflex is an involuntary, rapid, and often unconscious response of the nervous system to a stimulus. Reflexes are fundamental stereotyped behaviours that serve protective functions or maintain homeostasis.
Definition: A reflex is an involuntary and nearly instantaneous movement or action in response to a stimulus, mediated by a reflex arc.
Key Characteristics of Reflexes:
- Involuntary: Occur without conscious control.
- Rapid: Quick response time.
- Stereotyped: Consistent and predictable response to a given stimulus.
- Protective: Often serve to prevent injury or maintain internal balance.
Example: The knee-jerk reflex (patellar reflex) occurs when the patellar tendon just below the kneecap is tapped. This causes the quadriceps muscle to contract, leading to an involuntary extension of the lower leg. This is a monosynaptic reflex, meaning it involves only two neurons and one synapse.
Individual Behavioural Patterns
While stereotyped behaviours are common across a species, individual behavioural patterns refer to the unique variations or adaptations of behaviour exhibited by an individual organism. These patterns are often influenced by an individual's unique experiences, genetic predispositions, and environmental interactions. They contribute to the diversity of responses within a population.
Examples:
- A bird might develop a unique foraging technique based on the specific layout of its territory.
- An individual animal's preferred resting spot or specific route for travel.
- A predator's specific hunting strategy learned over time.
2. Instinct vs. Learnt Behaviour
Behavioural patterns can be broadly classified based on their origin: whether they are inherent or acquired.
Instinct
Instinctual behaviours are innate, unlearned, and genetically programmed. They are typically complex, involve a sequence of actions, and are performed without prior experience or training. They are crucial for survival and reproduction.
Definition: Instinct refers to a complex, unlearned, and species-specific pattern of behaviour that is genetically predetermined and performed without conscious thought or prior experience.
Key Characteristics:
- Innate: Present at birth or develops fully formed without learning.
- Genetically determined: Encoded in the organism's genes.
- Fixed Action Patterns: Often involve a series of predictable, unchangeable acts.
- Resistant to modification: Difficult to alter through experience.
- Examples: Spider spinning a web, bird migration, salmon swimming upstream to spawn, a baby suckling.
Learnt Behaviour
Learnt behaviours are acquired or modified through experience. They are flexible and allow organisms to adapt to changing environmental conditions. Learning enables individuals to develop new skills, avoid dangers, and find resources more effectively.
Definition: Learnt behaviour is a change in an organism's behaviour or potential for behaviour that results from experience. It is acquired, rather than inherited.
Key Characteristics:
- Acquired: Developed through interaction with the environment and experience.
- Flexible: Can be modified or adapted over time.
- Individual-specific: Varies among individuals based on their unique experiences.
- Examples: A dog learning to sit on command, a human learning to ride a bicycle, a chimp using tools.
Comparison: Instinct vs. Learnt Behaviour
| Feature | Instinctual Behaviour | Learnt Behaviour |
|---|---|---|
| Origin | Innate, genetic | Acquired through experience |
| Flexibility | Rigid, fixed | Flexible, adaptable |
| Development | Present from birth or develops without prior learning | Develops over time through interaction with environment |
| Species Variation | Common to almost all members of a species | Varies significantly among individuals |
| Persistence | Often permanent and unmodifiable | Can be modified, forgotten, or reinforced |
| Examples | Web spinning by spiders, bird migration | Learning to speak, riding a bike |
3. Associative Learning, Classical and Operant Conditioning, Habituation, Imprinting
Associative Learning
Associative learning is a fundamental type of learning where an organism learns to make connections between stimuli or between a stimulus and a response. This process allows organisms to predict events and adjust their behaviour accordingly, leading to more adaptive responses.
Definition: Associative learning is a learning process in which a new response becomes associated with a particular stimulus. It involves forming a mental link between two events.
The two primary forms of associative learning are classical conditioning and operant conditioning.
Classical Conditioning
Classical conditioning, also known as Pavlovian conditioning, is a type of learning in which a neutral stimulus comes to evoke a response after being repeatedly paired with a stimulus that naturally evokes that response.
Definition: Classical conditioning is a learning process involving the association of a neutral stimulus with an unconditioned stimulus, leading the neutral stimulus to elicit a conditioned response.
Key Concepts (based on Ivan Pavlov's experiments with dogs):
- Unconditioned Stimulus (UCS): A stimulus that naturally and automatically triggers a response without any prior learning. (e.g., food for a hungry dog)
- Unconditioned Response (UCR): The unlearned, natural, and automatic reaction to the unconditioned stimulus. (e.g., salivation in response to food)
- Neutral Stimulus (NS): A stimulus that initially produces no specific response other than focusing attention. It becomes a conditioned stimulus after repeated pairing with the UCS. (e.g., a bell sound)
- Conditioned Stimulus (CS): A previously neutral stimulus that, after becoming associated with the unconditioned stimulus, eventually comes to trigger a conditioned response. (e.g., the bell sound after being paired with food)
- Conditioned Response (CR): The learned response to the previously neutral (now conditioned) stimulus. (e.g., salivation in response to the bell sound alone)
Process:
- Before Conditioning: The UCS (food) elicits the UCR (salivation). The NS (bell) elicits no salivation.
- During Conditioning: The NS (bell) is repeatedly paired with the UCS (food). The bell is presented just before the food.
- After Conditioning: The NS has become the CS (bell), and it now elicits a CR (salivation) even without the presence of the food.
Example: A child who gets a painful injection (UCS) at the doctor's office (NS/CS) may eventually develop a fear response (CR) just by seeing a doctor's white coat (CS), even before any injection is given.
Operant Conditioning
Operant conditioning, also known as instrumental conditioning, is a type of learning in which behaviour is strengthened if followed by a reinforcer or diminished if followed by a punisher. This learning involves associating a voluntary behaviour with its consequences.
Definition: Operant conditioning is a method of learning that occurs through rewards and punishments for behaviour. An association is made between a behaviour and a consequence for that behaviour.
Key Concepts (based on B.F. Skinner's work):
- Reinforcement: Any event that strengthens or increases the frequency of a behaviour it follows.
- Positive Reinforcement: Adding a desirable stimulus to increase a behaviour. (e.g., giving a treat to a dog for sitting)
- Negative Reinforcement: Removing an aversive stimulus to increase a behaviour. (e.g., a car's seatbelt alarm stopping when the seatbelt is fastened)
- Punishment: Any event that decreases the frequency of a behaviour it follows.
- Positive Punishment: Adding an aversive stimulus to decrease a behaviour. (e.g., scolding a child for misbehaving)
- Negative Punishment: Removing a desirable stimulus to decrease a behaviour. (e.g., taking away a child's toy for misbehaving)
- Shaping: A procedure in which reinforcers guide behaviour towards closer and closer approximations of the desired behaviour.
- Extinction: The weakening and eventual disappearance of a learned response when it is no longer reinforced.
Law of Effect (Edward Thorndike): Behaviours followed by satisfying consequences are more likely to be repeated, while behaviours followed by unpleasant consequences are less likely to be repeated.
Example: A rat in a Skinner box learns to press a lever (behaviour) to receive a food pellet (positive reinforcement). If pressing the lever stopped an electric shock (negative reinforcement), it would also increase the lever-pressing behaviour.
Habituation
Habituation is the simplest form of non-associative learning. It involves a decrease in response to a stimulus after repeated presentations, especially when the stimulus is found to be neither harmful nor rewarding.
Definition: Habituation is a form of non-associative learning characterized by a decrease in the magnitude or probability of a response to a repeatedly presented stimulus that is neither noxious nor rewarding.
Key Characteristics:
- Stimulus-specific: The decrease in response is specific to the habituated stimulus.
- Reversible: If the stimulus is withheld for a period, the response may recover (spontaneous recovery).
- Adaptive: Allows an organism to filter out unimportant stimuli and conserve energy for more critical events.
Example: A new resident in a city might initially be bothered by the constant traffic noise. Over time, they habituate to the noise and no longer consciously notice it, allowing them to focus on other sounds.
Imprinting
Imprinting is a rapid and relatively irreversible form of learning that occurs during a specific, often very early, critical period in an organism's life. It typically involves forming a strong attachment to the first moving object or individual encountered.
Definition: Imprinting is a rapid and highly specific type of learning that occurs during a critical period in early development, often leading to a strong and irreversible attachment to the first encountered stimulus, typically a parent or caregiver.
Key Characteristics:
- Critical Period: Occurs only within a very specific and limited developmental window.
- Rapid: Learning happens very quickly, often within hours or days.
- Irreversible: The learned association is typically long-lasting and difficult to change.
- Species-specific: Although the object of imprinting can vary, the capacity for imprinting is innate.
Example: Konrad Lorenz's famous experiments showed that goslings would imprint on him if he was the first moving object they saw after hatching, following him around as if he were their mother. This bond was then very difficult to break.