Lizards fall for fake news

Not only humans sometimes “listen to” others even though they should know better.

Research showed that some Italian wall lizards (Podarcis siculus) copy the decisions of other individuals to go to food sources, they know from previous experience to not be accessible. Individuals that were faster at spatial learning were more prone to such social influence.

Researchers provided lizards with two platforms, each with a small transparent dish with worms. But one of the dishes was closed, meaning that the lizards could see and smell the food but couldn’t access it. That dish was always on the same side (left for some lizards and right for others) and marked with a background card of one specific colour (orange or green). The dish on the other side was open and marked with the other colour. Once the lizards learned where to obtain food, they watched another individual foraging. The demonstrator had learned before that the opposite dish (different side and colour) contained food, so they went there and ate the worms (for the demonstration researchers opened the dish). Then the observer was returned to their own setup and could make their own choice.

The question was: Will the observing lizard go to the location which they learned contains accessible food or follow the example of the demonstrator and go to the side they had previously experienced to be non-rewarding?

Many lizards went to the dish chosen by the other individual, even if they had undergone multiple demonstrations in which they experienced the food was still not accessible to them on that side. However, there were also lizards that were not affected by the social cue and just kept on choosing the side they knew had the open dish.

Therefore, lizards differed in their susceptibility to falling for “fake news” and researchers tested which aspect of cognition could be related to this. They had earlier performed a suite of different tests to assess inhibitory control, problem-solving, spatial learning, reversal learning and individual associative learning*. It seems that most of these aspects of cognition were not linked with a predisposition to copying social information, except for spatial learning. Individuals that were faster at learning the location of a hiding place were later more likely to follow the example of others.

Even though lizards are solitary animals and don’t have many social interactions they can clearly learn from others’ behaviour. This can be advantageous when searching for food as the presence of other lizards may be a good indicator of a good place to forage. Why some individuals tend to value information from others higher than their own previous experience is not yet clear. Maybe fast learners are just able to memorise and recall spatial information of the demonstrated location better than slower learners. Also, experiments on other species suggest that fast learners tend to use fresher information more. Additionally, it seems that at least some species of lizards rely more on spatial than colour cues when learning where the food is. This could explain why spatial learning, but not colour-associative learning, predicted the susceptibility to social influence in Italian wall lizards. While not addressed in this study, it is known from other animals that one’s personality can affect learning. For example, bold individuals tend to learn faster, quickly exploit social information and be more explorative and risk-taking. Therefore, differences in personalities could potentially also explain interindividual differences in lizards.

Whatever the reason that some animals follow other’s example instead of their own information, beware of fake news. And if you ever fall for them anyway, think about lizards.

* Inhibitory control was assessed by the time it took lizards to stop trying to attack worms behind a transparent wall of a dish directly instead of going over the wall. The shorter the time to actually reach the food the higher the inhibitory control. Problem-solving abilities were measured in two tests – opening a dish with food and escaping from a box. In the spatial learning task lizards had to learn which of the two hiding spots was safe from disturbances. In reversal learning, they were tested on how fast they learn again if safe and unsafe shelters were switched. The associative learning task had a setup similar to the social learning tests, but individuals were alone and the location of accessible food was variable. Only a specific colour was linked with accessible food.

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Photo: Mariomassone – Own work, CC BY-SA 4.0,

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