Key stimulation is congenital reflexes or reactions in animals that triggers a specific behaviour^[1]. Instinctive actions are only triggered by specific signals that could be compared to a key to a lock. It is different for every animal since they rarely have the same behaviour, unless they are part of the same species. An example is the northern pike. Small movements and/or something shimmering that could be compared to a smaller wounded fish is enough for it to strike. These things are triggering the behaviour caused by key stimulation. These movements and shimmers can be used by humans when fishing. Lures used while fishing are made to mimic these stimulations, which makes larger fish bite on to the lure.

Key stimulations can cause changes in the emotional state and motivation in larger animals, which in turn controls the animals’ behaviour. Even in humans the emotional state can be changed due to different stimulations.^[2] For example when humans see children or small animals, humans find them cute. This is caused by their characteristics, which is a key stimulation to humans that makes them change behaviour towards them.^[1]

The first to ever observe and describe key stimulation was Konrad Lorenz, who was a zoologist and ethologist. He created ethology and studied animals. Lorenz claimed that the behaviour had a genetic foundation, like birds being able to fly, not being something they have to be taught. He won the Nobel Prize together with Nikolaas Tinbergen and Karl von Frisch, who also were zoologists. Nikolaas (Niko) Tinbergen completed Konrad Lorenz’s observations about key stimulation with experiments^[3]. An example of an experiment is when he imitated animals’ key stimulations with the help of animal models. In one of his experiments he made a bird prototype where if moved in one direction made chickens think it was a hawk, which triggered their flight instincts. If moved in the opposite direction the chickens thought it was a goose and did not react. Even if the chickens did not have previous experience with hunting birds they automatically had the flight instincts when they saw the silhouette moving in the direction where it looked like a hawk.^[1]

For a specific key stimulation to be active, the animal needs to be motivated. An example of this is when the European robin behaves aggressively when they see other birds that have the colour red during breeding season. The colour motivates them to attack birds with the colour, as it is a key stimulation. They even attack red tassels of feathers, which show that the colour is what makes them react. When the breeding season is over the European robin leaves their territory and no longer feel the need to attack other birds. The European robin no longer has anything to defend and therefore lack motivation.     

There are many different motivational actions. One of them is fix motion pattern, which is a behaviour that is triggered by a key stimulation that always is performed the same way. The behaviour is performed even if the key stimulation stops.

 Another action is taxis, which is when a key stimulation triggers a movement towards or away from the source of the stimulation. For example if a woodlouse is exposed to sunlight, they will move towards an area where it is darker. Moths also react to light, but they are drawn to the light instead.

An animal can also perform an instinctive action, even though there are no key stimulations. When this happens the animal performs an idling action^[4]. In association with high motivation, behaviour can be triggered by faulty key stimulations. This can be called unmotivated behaviour. An example of this is when capercaillie males have not had the chance to mate in the spring. This causes the males to direct their mating behaviour towards other animals, even humans.

Sometimes animals react stronger to exaggerated key stimulations than to regular ones. This is called supernormal stimulation. When you fish, you take advantage of fishes exaggerated stimulations. The fishing lures do not have to look like fish. It is enough for the lures to move and shimmer like a fish.

Sometimes key stimulations can trigger two behaviours simultaneously. If the behaviour goes against each other the animals feel stressed, and a third behaviour is triggered. The animals perform a so called displacement activity. For example when humans hesitate on different answers to a writing question they might scratch their heads or start biting their nails.^[5]

Different kinds of animals can have similar key stimulations, for example frogs and spiders. They both react to moving insects. Spiders react when they feel vibrations in their web from insects moving, and frogs react when they see the insects move, which makes them throw out their tongue. Both of the species can have faulty reactions. The frog can for example have a dead insect in front of it, and if a piece of paper is moved in front of the frog it will react to that and not the insect, because of the movements the paper makes. Spiders will react to any vibrations in their web. If you for example touch the web lightly the spider will move to the location of the vibration, thinking it was a prey. ^[6]

https://upload.wikimedia.org/wikipedia/commons/6/63/Tinbergen_goose-hawk.png 29/11-2017 (bild 1)