In marker training, an animal is shown by a — usually acoustic — signal (so-called marker) that it is behaving correctly at a certain moment. The signal also announces a reward. A frequently used marker signal is a 'click’ sound, which is produced by pressing a small hand-held device known as a ‘clicker’. Alternatively, it is also possible to click your tongue or use a whistle (which is often used for training zoo animals). A marker word — a short word that is rarely used in everyday life, such as ‘click’ or ‘top’ — is also an option. 

When carried out correctly, this clear and unambiguous form of communication is an effective and animal-friendly way of training an animal to perform any behaviour that it is physically and mentally capable of. It can be used in many areas of animal training: ranging from everyday training, obedience exercises/testing, learning tricks and physical activity/movement exercises to working on unwanted behaviours that can cause problems in everyday life.

• How do marker signals work?
• What should I bear in mind when training a dog with marker signals?
• Why are marker signals so effective?
• Why is it not enough to just give the animal a treat?
• What should be considered when using a marker word?
• More information about ‘clicker training’

For an animal to be trained with a marker signal, it must first understand the association between the marker — which is intended to mark a certain behaviour — and the positive reinforcement, which is the announced reward. To do this, it must first be conditioned to the marker. Thus, it receives a reward such as a treat/food after each marker, e.g. if this is the greatest reward for the animal. If this process is repeated a few times, the animal associates something positive with the marker signal. You can then actively use the selected marker (click, whistle, word, etc.) to mark and directly reward the desired behaviour. This will positively reinforce the animal's behaviour, which will then show it more often. Using a dog as an example, this can be done in various ways:

• You can ‘capture’ behaviours, i.e. you mark the desired behaviour while it is already being shown. For example: the dog is lying down — even though they usually find it difficult to lie down — and you click and reward them for it.
• Alternatively, ask the dog to sit down and mark the moment its bottom touches the ground.
• Another option is to shape a behaviour by marking and rewarding the first behaviours that come close to the target behaviour in small steps.

The animal will quickly recognise the connection between the signal and the reward, sometimes after just two or three repetitions. As it wants to repeat the pleasant experience (and positive reinforcement of certain behaviours), it will repeat the behaviour desired by the human more often. 

What is easy to remember: A marker signal is like the precise photographic recording of a behaviour that you want to reinforce or strengthen. Once the ‘picture has been taken’, it is consolidated with the help of a reward. Marker signals can therefore be used in a variety of different ways.

It is important to give the dog an idea of what you want them to do. For dogs that may be less creative or not used to initiating different behaviours on their own, it can otherwise lead to frustration or a slow training progress. Here it helps to give the dog an idea or clearer guidance of what is expected of them by initially luring them with food or (inviting) hand movements. It is easier and more effective for all dogs to proceed in small steps, to let them actively learn from success and thus lead them to the desired target behaviour. 

Caution: With some very active dogs or very fast-learning, cooperative breeds such as the Border Collie, which quickly become very enthusiastic and overly excited, clicker training must be used in moderation — less is often more here. 

In marker training, for example, you can concentrate very well on the issues of leash aggression or exaggerated barking behaviour by clicking/marking and rewarding the dog when it is still calm. This means that you reinforce the desired behaviour — i.e. the calm behaviour — before the dog shows the unwanted behaviour, such as pulling on the lead, lunging or barking. 

Marker signals initially utilise classical conditioning: each time the ‘marker’ (click/word signal etc.) is immediately followed by a pleasant reward such as food. In this case, the food is a primary reinforcer and something that the dog, cat, etc., would like to have. After several repetitions, the animal automatically associates the marker with something pleasant. As soon as the animal later repeats specific actions, for example desired behaviours, in order to receive a marker signal or, better, the associated reward, operant conditioning sets in. The marker signal is therefore a secondary reinforcer or bridge signal that specifically marks the desired behaviour and announces the pleasant reward (as a bridge). 

The great advantage of operant conditioning is already apparent: The animal doesn't just react, it acts; it becomes active and consciously takes action. As training with marker signals only uses positive reinforcements, the animal becomes a proactive, happy partner in training. In addition, humans concentrate more on the positive, the desired behaviour already shown by the animal, instead of just reacting to possible mistakes. When training with positive reinforcement, the animal enjoys learning and is motivated because it strives for the reward and learns from success and not to avoid punishment. 

The marker signal makes it possible to capture and mark a behaviour with pinpoint accuracy — reaching for the treat bag can never be as timely and precise as the confirmation by the marker signal. However, the marker signal gives the trainee time to reach for the treat bag. Ideally, the reward is given within about 2 seconds after the signal —  so it is important to have the treats to hand. 

So that the animal can clearly recognise the marker word from a large number of words, it is important to choose a concise, short word that is unusual in everyday life. What's more, the human voice often adapts to emotions — depending on the owner's mood, even praise can sound like punishment or dissatisfaction can resonate subliminally. You should therefore make sure that you always pronounce the chosen marker word in as constant a voice pitch as possible. 

If the animal finds the marker signal and the reward motivating and pleasant, this can be particularly effective in the initial phase of training in order to establish desired behaviours or, for example, new everyday exercises/routines etc. Once a desired behaviour has been repeated often enough and is established, you can vary the frequency of the reward by only occasionally marking and rewarding the best repetitions or not rewarding them at all; but at best it should be a smooth transition and individually adapted —  depending on the dog's frustration tolerance. In general, after a certain training period, it is advisable to click/mark at irregular intervals or only when the behaviour is performed particularly well in order to maintain motivation instead of reducing the value of the reward (the attractiveness of the reward from the dog's point of view, e.g. less flavourful treats or praise instead of treats). 

The training method developed by US animal trainer Karen Pryor can and has been used successfully on animals of all sizes and species, whether domesticated or wild, young or old: dogs, cats, birds, leopards, rats, rabbits, chinchillas, guinea pigs, fish, lions, some tigers in the FOUR PAWS sanctuaries such as FELIDA Big Cat Sanctuary in The Netherlands. Karen Pyor has used marker training in her work with dolphins, for example. When training marine mammals, a whistle is often used as a marker signal to free up the hands. 

The advantage of a clicker over word signals is that this device produces a unique and unambiguous signal with a high recognition value. In contrast to word signals, its acoustics, sound, and meaning are always the same and independent of mood. The disadvantage is that it has to be used by hand. However, you can attach it to your wrist with a strap, which makes it easier to use. There are now clickers that you can put on a finger like a ring. 

FOUR PAWS uses clicker training in its bear sanctuaries, including BEAR SANCTUARY Müritz in Germany, BEAR SANCTUARY Domazhyr in Ukraine and BEAR SANCTUARY Prishtina in Kosovo. The main aim of clicker training here is to ‘communicate’ with the animals and to train cooperative behaviour with the bears, which is important for administering medication or examining the teeth, for example. It helps to build trust between both sides and thus creates a relationship between the animal and its carer. Daily contact with each other, as well as any necessary medical treatment, will be much less stressful for both sides. Clicker training is also used to keep animals busy and mentally stimulate them (to reduce anxiety and stress) to improve their physical and mental well-being.

Training with marker signals, such as a clicker, is a positive and needs-orientated training method. The absence of any punishment or coercion enables even shy and fearful animals to learn in a way that is characterised by joy and enthusiasm. The animal not only gains self-confidence, but also learns a wide range of desired behaviours quickly and effectively. Another key benefit: training using positive reinforcement strengthens and intensifies the bond and trust between animal, pet owner, carer, and trainer.