tags: - colorclass/evolutionary psychology ---## Fixed Action Patterns (FAPs)
Fixed Action Patterns (FAPs) are sequences of innate behaviors that are highly stereotyped, meaning they follow a predictable and unchangeable sequence once initiated. These behaviors are triggered by specific external stimuli known as sign stimuli or releasers. Fixed Action Patterns are an essential concept in ethology and are crucial for understanding instinctive behaviors in animals.
Characteristics of Fixed Action Patterns
1. Innate Behavior: FAPs are instinctive and do not require learning or experience to be performed correctly. 2. Triggered by Specific Stimuli: A particular sign stimulus or releaser is required to initiate the FAP. 3. Stereotyped Sequence: The behavior follows a precise and predictable sequence that is performed in the same way each time. 4. Once Initiated, Runs to Completion: Once an FAP is triggered, it will continue to completion, regardless of changes in the environment. 5. Species-Specific: FAPs are typically species-specific, with different species exhibiting unique patterns of behavior.
Examples of Fixed Action Patterns
Egg-Rolling in Graylag Geese
One of the classic examples of an FAP is the egg-rolling behavior in graylag geese, studied by Konrad Lorenz. When a goose sees an egg outside its nest, it uses its beak to roll the egg back into the nest. The sight of the egg (sign stimulus) triggers the rolling behavior, which continues until the egg is back in the nest, even if the egg is removed during the process.
Stickleback Fish Aggression
Male stickleback fish exhibit a fixed action pattern of aggressive behavior triggered by the sight of a red belly, which they associate with rival males. During the breeding season, a red-bellied model or another male stickleback will trigger a series of aggressive displays and attacks. This behavior is highly stereotyped and continues until the intruder is chased away.
Yawning in Humans
Yawning in humans is considered an FAP. It is triggered by seeing someone else yawn (contagious yawning) or by a feeling of tiredness (internal stimulus). Once initiated, the yawning sequence follows a stereotyped pattern of opening the mouth, inhaling deeply, and exhaling, and it runs to completion.
Courtship Behavior in Birds
Many bird species exhibit fixed action patterns during courtship. For example, the courtship dance of the male three-spined stickleback involves a series of precise movements to attract a female. These behaviors are triggered by the presence of a female and follow a specific sequence.
Mechanisms Underlying Fixed Action Patterns
Neural Circuits
FAPs are controlled by neural circuits that are hardwired in the animal’s brain. These circuits are often simple and involve a series of neural connections that translate the sign stimulus into a fixed sequence of motor actions.
Genetic Basis
The development and expression of FAPs have a genetic basis. Genes influence the structure and function of the neural circuits responsible for these behaviors. Selective breeding experiments have shown that FAPs can be modified through genetic selection, indicating their heritable nature.
Sign Stimuli and Releasers
Sign stimuli are specific environmental cues that trigger FAPs. These stimuli are often simple and salient, ensuring that the behavior is reliably initiated in appropriate contexts.
Supernormal Stimuli
Supernormal stimuli are exaggerated versions of natural sign stimuli that elicit stronger responses. For example, birds may prefer to incubate larger artificial eggs over their natural ones because the exaggerated size is a more potent stimulus.
Mathematical Modeling of FAPs
Consider a model where the probability ( P ) of an FAP being triggered is a function of the strength ( S ) of the sign stimulus:
where: - ( \alpha ) is a constant representing the sensitivity of the animal to the sign stimulus, - ( S ) is the strength of the sign stimulus.
As ( S ) increases, ( P ) approaches 1, indicating a higher likelihood of the FAP being triggered.
Implications of Fixed Action Patterns
1. Understanding Animal Behavior: FAPs provide insights into the innate components of animal behavior, highlighting the role of genetics and evolution in shaping behavior. 2. Behavioral Ecology: FAPs are crucial for survival and reproduction, as they often involve essential activities such as foraging, mating, and predator avoidance. 3. Animal Welfare: Recognizing FAPs in captive animals can help improve their welfare by providing appropriate stimuli and environments that allow for the expression of natural behaviors.
Further Reading
- Konrad Lorenz - Animal Behavior - Behavioral Ecology - Neuroethology - Supernormal Stimuli
Fixed Action Patterns are a fundamental concept in ethology, illustrating the innate and stereotyped nature of certain animal behaviors. By studying FAPs, researchers gain valuable insights into the neural, genetic, and evolutionary mechanisms underlying animal behavior.