Aggression: Ethological explanation Flashcards
What is ethology?
The study of animals in their natural environment.
Lorenz defined aggression as…
The fighting instinct in man and beasts which is directed against members of the same species.
What are innate releasing mechanisms?
A built-in psychological process or structure that an environmental stimulus (e.g. facial expressions) stimulates to initiate a set of specific behaviours.
Innate-releasing mechanisms are biologically hard-wired mechanisms for aggression (e.g. brain structures or neural pathways for aggression). Environmental cues (e.g. the red belly of a rival stickleback) trigger the innate releasing mechanism. This releases a fixed action pattern of behaviour.
What are fixed action patterns?
The sequence of behaviours that occur within a species, so all members act this way. Said to be innate.
An example of a fixed action pattern can be seen in stickleback fish:
During the mating season, male sticklebacks build nests where females lay eggs
(Male sticklebacks also develop red bellies during this time)
If another male enters their territory, the stickleback will attack it
Why is aggression adaptive?
Survival: Aggression promotes survival. A defeated animal is not always usually killed. Instead, they’re excited and seek territory elsewhere.
Dominance: Aggression is used to establish dominance hierarchies. Dominance gives the victor special status.
Describe the purpose of ritualistic displays of aggression.
Lorenz observed that animals rarely engage in actual physical fighting. Instead, time is spent on ritualistic ‘signals’ (e.g. facial expressions). Also, defeated animals show signs of ‘appeasement’ (acceptance of defeat), and are usually not killed. These behaviours are adaptive, because the injury or death of an animal reduces its population numbers and threatens the species’ existence.
Describe a study that shows humans using ritualistic aggression?
Found (1978) found evidence of highly ritualised ‘fighting’ among males of the Gaelic speaking tory island off the coast of Ireland where threat displays appear to take place of actual aggression.
What is appeasement?
If one animal feels the other is stronger it will show signs of submission such as rolling over and showing a vulnerable spot.
Showing signs of defeat
What is the hydraulic model?
The hydraulic model visualises pent-up aggression an animal may experience and release, taking into account IRMs and FAPs and acknowledging motivation in animal behaviour. Interestingly, Lorenz’s hydraulic model of instinctual behaviour goes back to the work of Freud. He believed that aggression was an inevitable outcome because, in his view, animals, especially males, are biologically programmed to fight for what they deem necessary for their survival. These include food, territory, and the right to mate.
Motivation is the fluid that accumulates in the reservoir and becomes the drive to act in this mechanism.
- Action-specific energy or pent-up aggression accumulates in the reservoir, and the sign stimulus serves as the trigger. In this case, the stimulus is the weight that clogs the reservoir.
- A sign stimulus will ‘release’ the pent-up reservoir, resulting in FAPs, and FAPs can vary depending on how much the reservoir releases.
What was Timbergen’s stickleback study?
Tinbergen (1952) demonstrates how fixed action patterns in sticklebacks are universal. When Tinbergen presented male sticklebacks with models of fish with red bellies (even when the model was not realistic looking), they all responded with the same fixed action pattern of fighting behaviour. The universal nature of this behaviour suggests the fixed action pattern is innate.
A03: Ethological explanations of aggression
+ Tinbergen’s research support
+ RLA
- Fixed action patterns are not fixed
- Generalised findings
Tinbergen’s research support
One strength of the ethological explanation of aggression can be seen in the findings of Niko Tinbergen’s (1951) study with male sticklebacks. They are very territorial during the spring mating season where they also develop a red spot on their underbelly. Tinbergen found that after presenting male sticklebacks with a series of wooden models of different shapes, the sticklebacks would aggressively attack the model if it had a red spot. But if there was no red spot, even if the model looked realistically like a stickleback, there was no aggression shown. He also found evidence to support the existence of an FAP in the male sticklebacks.
RLA
Another strength of ethological explanation can be seen in anthropological evidence providing RLA suggests that the Yanomamo people of South America settle a conflict through chest pounding and club fighting contests which result in less extreme violence similar to the ritualistic aggression shown by other animals which prevent conflicts from escalating to potentially dangerous physical aggression. This supports the theory as Chagnon (1992) was able to witness this behaviour in humans and not just animals, allowing us to more confidently generalise this theory to animals.
Fixed action patterns are not fixed
A further limitation is an evidence that fixed action patterns are not fixed. Hunt (1973) points out that sequences of behaviour that appear to be fixed and unchanging are greatly influenced by environmental factors and learning experiences. This means that FAPs are more flexible than implied by the term ‘fixed’. Many ethologists now prefer the term modal action pattern to reflect this. The flexibility of FAPs suggests aggressive behaviours are affected by environmental influences, challenging the validity of the ethological explanation.
Generalised findings
One limitation is unjustified generalisations to human aggression. Lorenz did not study higher mammals such as primates, and Tinbergen chose not to study the extreme destructive violence that is a feature of human aggression. But they both made generalisations from animal aggression to humans, including warfare. Lorenz extrapolated from the behaviour of individual animals to the behaviour of entire countries. We should be cautious about making such generalisations especially to a complex behaviour such as warfare which is the outcome of many interacting influences.
