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Mental Immunity: How and Why Animals Filter Misinformation

Nonhumans have to be able to screen out "mind parasites" and do what's right.

Key points

  • Various mechanisms have evolved in animals to counter misinformation. 
  • One such mechanism is imprinting, in which young animals rapidly learn to attend to and follow the first object or individual they see or hear.
  • Another safeguard to being misinformed is to be born in a relatively advanced state of development in order to survive on one's own.

Andy Norman's essay "The Surprisingly Deep Roots of Mental Immunity Research" with a teaser image of a thinking gorilla got me thinking about how nonhuman animals (animals) avoid using misinformation and combat cognitive contagion.1 He begins, "The mind has infrastructure for filtering information. This infrastructure functions like the body’s immune system: When working properly, it screens out the bad stuff—false, misleading, and dysfunctional ideas—and lets in the good stuff, ideas that are accurate and useful."

Andy's teaser image made me think he'd write some on animals but he didn't, and given my nonhuman proclivities, I thought about how his novel ideas, developed more fully in his outstanding book, Mental Immunity: Infectious Ideas, Mind-Parasites, and the Search for a Better Way to Think, would apply to nonhumans and what an evolutionary, comparative perspective could add to future conversations about these seminal ideas.

Following up on Andy's suggestion that it's possible to study mental immune systems the same way we study other natural systems, I thought about how possible mechanisms to counter misinformation—what he calls "mind parasites"—might have evolved in nonhumans, though some might also apply to humans.

Hard-wired and learned mechanisms for avoiding being misinformed

Generally speaking, being misinformed can get you killed, whether you’re a human or nonhuman. Wild animals, and, of course, companion animals need to be able to figure out—often instantaneously and on the run, so to speak—what or who is dangerous and what or who isn't. A single mistake can be injurious, life-threatening, or fatal and should be avoided at all costs.

There are some historical thoughts about some of these ideas in classical ethology. For example, various mechanisms have evolved to counter misinformation including behaviors called Fixed Action Patterns (FAPs) and Modal Action Patterns (MAPs). There also are phenomena such as imprinting, behavioral and sensory polymorphisms, precocity, and altriciality.

FAPs/MAPs. Classical ethologists and 1973 Nobel Laureates Konrad Lorenz and Niko Tinbergen (who shared the prize with Karl bon Frisch, discoverer of bee language) developed ideas about FAPs and recognized these as "fundamental units of behavior that help organisms to navigate the environment, detect necessary resources, avoid danger, and interact with others."

FAPs are innate, highly invariable or stereotyped, and genetically based. Across different species, various warning sounds, colors, and actions called "sign stimuli" or "releasers" have evolved to elicit specific actions such as following a trusted caregiver (imprinting), begging for food, or avoiding danger so that animals avoid being misinformed, harmed, or killed. They are controlled by Innate Releasing Mechanisms (IRMs) in the brain.

The late ethologist George Barlow introduced the idea of "Modal Action Pattern" to recognize that FAPs often show some variability and aren't really "fixed" but can still be recognized as being important signals to get an organism to do something specific.

Marc Bekoff
Source: Marc Bekoff

A good example of a MAP is the play bow that dogs and other animals use to ask other individuals to play and to maintain the "play mood" because it's essential to communicate their intentions correctly and unambiguously—that they want to play rather than fight with, mate with, or eat another dog(s)—and not be misunderstood. This is one way to keep play fair and safe for the players.

Imprinting, a concept for which Lorenz is often given credit for formalizing, involves a newborn or young animal rapidly learning to attend to and follow the first object or individual with which they have contact via vision, hearing, or touch. In the natural world, the first individual is typically a harmless friend such as their mother or other family or group member. Imprinting can aid in species recognition and imprinting to sounds can occur prenatally.

Behavioral and sensory polymorphisms: Imprinting to the correct stimulus is so important that in broods of Pekin ducklings a fascinating back-up insurance mechanism has evolved so that things go right when the ducks are very young and have to stay near their mother. This trait is called a "behavioral polymorphism." As it turns out, some ducklings in a brood are more sensitive to sounds, whereas other siblings are more sensitive to visual stimuli. This means that ducklings will follow other ducklings, some of whom are more sensitive than they are to different stimuli. The researchers write, "variability in modality of sensitivity may be adaptive to the brood since it generally follows the most responsive individual in any situation." Auditory imprinting occurs earlier than visual imprinting so that ducklings who don't hear as well will still follow their siblings.

Precocity and altriciality: Another safeguard to being misinformed is to be born in a relatively advanced state of development and to be able to do what needs to be done to survive pretty much on your own. Some birds such as ducks and geese and mammals such as ungulates are born in a relatively advanced state of development. Their eyes are open, they can thermoregulate to some degree, and they are able to walk or run. These youngsters are labeled precocial.

On the other hand, for infants born in an undeveloped helpless state, there is extensive parental care and also other adults who serve as caregivers and protectors until the youngsters are able to take care of and fend for themselves. Infants born in this state are labeled altricial.

Where to from here? A natural history of mental immunity

Taken together, the mechanisms above and perhaps others have evolved as adaptations for countering misinformation. Of course, individual learning also is important for filtering out the bad from the good, and many forms of learning, including dog training and other types of behavior modification, fall within the broad scope of mental immunity.

I see cognitive immunity as a ubiquitous umbrella for explaining a wide variety of ways in which humans and nonhumans avoid being misinformed. Applying some of its unifying underlying principles to nonhumans is an exciting area for comparative research, and while there have been studies of some of the ways in which nonhuman animals avoid being misinformed and misled, they have not been cashed out as being forms of mental immunity.


I thank Andy Norman for reading this essay. More information can be found at the website for The Cognitive Immunology Research Collaborative

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When Dogs Play, They Follow the Golden Rules of Fairness.

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Play Signals as Punctuation: The Structure of Social Play in Canids. Behaviour, 132, 419-429, 1995.

Brown Grier, J. et al. Prenatal Auditory Imprinting in Chickens. Science, 155, 1692-1693, 1967.

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Klopfer, Peter and Gilbert Gottlieb. Imprinting and behavioral polymorphism: Auditory and visual imprinting in domestic ducks (Anas platyrhynchos) and the involvement of the critical period. Journal of comparative and Physiological Psychology, 55, 126-130, 1962.


McCable, Brian J. Visual Imprinting in Birds: Behavior, Models, and Neural Mechanisms. Frontiers in Physiology, 2019.

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