What is cognition?

“Cognition” is one of those terms that we use a lot, but which is actually rather hard to define. The question of what constitutes cognition looms large in debates about whether other organisms, besides humans, do it or have it. Most people are willing to grant that many animals are in some way cognitive, but what about simpler critters, like nematodes or jellyfish? Are they capable of cognition? For that matter, what about bacteria or plants? Can they cognize? How about artificial systems, like large language models?

Does cognition require a nervous system? Does it necessarily involve “thinking”? Or some kind of “mental” activity? Once you start defining it in that rather circular fashion, you quickly realise we don’t have good definitions of “thinking” or “mental” either!

 

Is cognition just “what cognitive scientists study”? Or are they only studying a particular version of it – the kind of cognition we see in humans? Maybe there is a less anthropocentric way to define it – one that recognizes some abstract principles that may be realised in different ways in different kinds of organisms.

 

To that end, I posed the question on Bluesky: “how would you define ‘cognition’”? There were lots of replies, from neuroscientists, cognitive scientists, psychologists, philosophers, computer scientists, and others. (Thread here, from January 2025)

 

I’m hugely grateful to everyone who replied and hope they won’t mind me listing their (anonymised) answers below. What’s fascinating is how diverse the replies were. They run the gamut from “information processing by goal-directed systems” to “all the processes between perception and action” to definitions that use high-level human psychological terms like “thinking”, “planning”, and other kinds of “mental operations”. Many definitions emphasized what cognition is for: problem-solving and using information to adapt to the world.

 

You can peruse the list below. I’ll give my own definition at the bottom, along with some further thoughts on how – beyond simply looking for a definition – we might usefully think about cognition. Here’s the list:

 

 

Cognition is:

 

The stuff that happens between 'perception' and 'action'

 

Anything about how organisms interact with the world that is not sensory or motor.

 

Considering most of the so-called cognition happens unconsciously and our poor knowledge of the brain functioning, cognition is currently a black box between sensory stimuli and motor actions.

 

Information processing in the brain.

 

Information processing done by goal-directed systems.

 

The problem-solving part of the organism, excluding management of bodily functions.

 

The information processing aspect of living systems. So it’s intimately entwined with life, but not the same.

 

Processes that allow you to act efficiently in contexts with different degrees of uncertainty.

 

The set of things needed to support skillful and intentional activity in the world

 

How our minds work to interpret the world

 

Mental actions or processes. Neural actions or processes may be the underlying mechanism, but are not themselves called "cognitive." Cognitive neuroscience studies the biological mechanisms of cognition.

 

Any process where the input, output, or intermediate steps (preferably all) is mental/phenomenal/in the mind.

 

All things providing knowledge/meaning of the world.

 

Reasoning, decision-making, planning.

 

The set of mental processes involved in acquiring, processing, storing, and using information

 

The ability to synthesize information contained within external stimuli into meaningful interpretations of one's surroundings and current state.

 

Sensory and other information-processing mechanisms an organism has for becoming familiar with, valuing, and interacting productively with features of its environment in order to meet existential needs.

 

A property of an agent whereby the behaviour is a kind of possibly partial function/algorithm of some sensory input, over the agent's history.

 

Brain's specific active contribution to mind is what we call cognition.

 

The ability of an animal to separate itself from the moment in which it is living and to contemplate the past, predict the future, and act accordingly

 

Some task that requires non-trivial amounts of information processing, pattern recognition, working with levels of abstraction and composing of solutions to other cognitive or information processing tasks.

 

The entirety of mental process of acquiring knowledge and understanding through thought, experience, and the senses and using this culmination of knowledge to guide future behaviors.

 

Body-mind categories of understanding that help an organism interpret, generalise, schematise, and systematise complex sets of sense data into relevant information in its milieu.

 

What enables an organism to adapt to its environment at a speed faster than what's achieved by evolutionary changes to its body.

 

Creating and maintaining an internal mental model of the outside world.

 

Non-equilibrium thermodynamics sustained by information processing.

 

The generation of meaning in relation to the environment. It is enacting a world.

 

A concept which exists in the mind of human observers, variously defined and applied to conceptually delineate some subset of adaptive activities in living systems... ...and which is often mistaken for a naturally delineated constituent property of the living systems under study.

 

 

 

And, finally, one respondent pointed out this very helpful resource, where someone did a very similar exercise, with equally diverse answers: http://www.vernon.eu/euCognition/definitions.htm

 

 

 

 

For what it’s worth, here’s my own definition:

 

Cognition is using information to solve problems and guide adaptive behavior.

 

To be very clear, I’m not claiming that’s the “right” definition! I don't think there is a right definition. It’s a pragmatic issue – a question of what kind of thing we are aiming to pick out in the world, and why. What are we trying to achieve in recognising and naming this capacity or type of process? For me, the goal is to get at the underlying principles at play that make some activity cognitive.

 

For that reason, I tried to couch my definition as abstractly as possible. I think it is broad enough to encompass capacities that share underlying principles but that vary hugely in sophistication across different kinds of creatures.

 

I would personally argue that even simple phenomena like bacteria integrating information about what is out in the world and mounting an appropriate response to the situation as a whole entails at least a basal kind of cognition (and agency). It’s not a full-blown psychological process, and there’s no reason to think of it as mental (whatever that means), but it’s more than a simple stimulus-response mechanism.

 

That position is clearly arguable, of course, and there’s not really much point getting hung up on semantics. No one needs to be the “cognition” police. What’s more interesting is to try and dig in a bit – to move beyond that simple question to try and tease out what the concept of cognition is actually getting at.

 

My original question was simply: How would you define cognition?

 

I could have asked that in another way, which might have helped avoid the more circular, anthropocentric definitions: How would you define cognition without appealing to the terms “mind” or “mental” or words like “thinking”? That exercise might force some deeper introspection of the underlying principles.

 

But there are other questions we could ask that might get at something deeper, beyond the mere definition of the term:

 

What is cognition for? What kinds of tasks are “cognition-hungry”? I mean, what sorts of problems require cognition and what sorts don’t? Getting energy through photosynthesis doesn’t, but hunting prey does. Digesting food doesn’t, but remembering where you cached it does. Walking on an even surface doesn’t, but climbing over a wall does. Right? (That last one is certainly arguable).

 

We could also ask, from a third-person perspective, what kinds of behaviors would we take as evidence that “cognition” is happening or that a system is “cognitive”? Or, zooming out, what kinds of lifestyles, ecologically speaking, would favour the evolution of cognitive systems?

 

Here is a rough list of things we might consider as elements or functions of cognition, arranged in ascending order of sophistication:

 

·      Behaving adaptively

·      Using information to behave adaptively

·      Integrating or synthesising information to behave adaptively and flexibly

·      Operating over information to solve problems in order to behave adaptively and flexibly

·      Interpreting information in the context of stored knowledge

·      Operating over semantic information at a symbolic level

·      Operating over symbolic information at a conscious level

 

It would take some work to flesh out the differences between “using”, “integrating”, “synthesising”, “interpreting”, and “operating over” in those contexts. I’m not even sure what I mean by all those terms, except that the ascending scale loosely implies a greater degree of internal goings-on, more linked to stored schematic knowledge and higher-order, maybe even abstract concepts. So the “information” in question may be simply incoming streams of sensory data, but could also refer to semantically meaningful information, even possibly conceptual information that is divorced from current stimuli, or encoded at a symbolic level. Where we might want to draw the “cognitive” line is thus very open to debate.

 

Perhaps we could think of adaptive processes in ascending order too:

 

·      Control

·      Computation

·      Cognition

·      Cogitation

 

I certainly don’t think that all cognition has to be conscious or involve what we think of in humans as cogitation – operations in some kind of mentalese. In fact, I think it’s worth asking whether cognition necessarily implies mentality at all. Or is doing cognitive processes mentally just one of the ways to do them? Is a computer that solves some problems algorithmically doing cognition?

 

The most basic definitions in the list above almost seem co-extensive with “life”. Is all life cognitive? Humberto Maturana and Francisco Varela influentially argued so. And some contemporary scientists like Mike Levin argue that even processes of embryonic development are essentially cognitive.

 

Does the word lose its usefulness if we extend it so far? While cognition itself refers to some internal processes, we typically recognise it in the capacities of organisms to solve problems out in the world. Is a bacterium regulating its profile of gene expression in response to information about changing circumstances engaging in a cognitive process? Or does the term “physiology” do the trick? Are the cells in an embryo doing cognition to figure out where they are and what they should turn into? Or is “development” already sufficient to capture those processes?

 

Perhaps we should say that cognition is something that a whole organism does. There may be all kinds of adaptive, responsive processes happening within an organism that might not rise to this level. Again, it depends on what we want the word to pick out. All living things are entities that use information to solve the most basic problem of persisting. But are they all using it in a cognitive way?

 

I don't have any answers, but perhaps the questions themselves are useful.