Goal-Directed Agency and Intentional Agency

Index to posts in this series


Lizards are a representative of the first category of agency according to Michael Tomasello in his book The Evolution Of Agency. As with the other categories, Tomasello focuses on the way lizards forage for prey. C. elegant, the nematode we looked at in the last post, moves and food either does or doesn’t go into its mouth. That obviously won’t work for lizards. Most species survive largely on a diet of insects, small creatures that move and flit about unpredictably.

So lizards have a different strategy. They have a goal, finding food, but they have to do several things to reach that goal. They have leave their hiding places and move to a place where there are insects. They have to spot a specific insect and then catch it and eat it. At the same time, they have to make sure they don’t become prey for other creature.

Here’s a video of a guy feeding crickets to his pet crested lizard. The lizard is in a special feeding cage. The crickets must be alive or the lizard won’t eat them. Bonus: you learn a new term: gut-loading crickets.

Following Tomasello here’s how I read this video. The lizard stands still orienting itself to its surroundings. The guy throws a cricket into the cage. The lizard sees the cricket. It takes a few steps forward. It pauses. It charges and grabs it and eats it. The guy throws another cricket into the cage. The lizard sees it, turns to chase it, misses, and pursues it in short bursts. It catches and eats the cricket. The guy throws a bunch of crickets into the cage. The lizard singles out one, chases, catches and eats it. The other crickets run around. The lizard spots one, chases, catches and eats it. This is repeated.

In this video we see a frilled lizard, a native of Northern Australia and southern New Guinea. It’s about a meter in length, and weighs over a pound. This video is heavily edited but again following Tomasello, here’s how it can be read. The lizard descends from it’s hiding place in a tree. It forages for prey, meaning any insect it might find on the ground. It sees one, approaches, catches and eats it. While chewing it looks around. It spots a predator, a black-headed python. It’s frill blows up. The snake approaches. The lizard runs really fast (also amusing). It eventually runs up a tree, making a full escape.

Tomasello says that the lizard has hard-wired goals: including eating and avoiding predators. Both it’s prey and its predators are quick and unpredictable. It has evolved to deal with that unpredictability by paying attention to the crucial aspects of the situation it perceives at any moment. It then acts to achieve a goal applicable to that situation. In both videos, the lizard eats while checking the situation. In the second it detects danger. It freezes its eating, then flares its frill, then runs. It achieves its goals by a series of go-no go decisions. That’s a clear step up from C. Elegans.


Squirrels are Tomasello’s example of intentional agents. He gives an example of a squirrel on a tree branch spotting a nut on a lower branch. The problem is whether to jump to the lower limb or retreat to the trunk and run down to the lower branch. He says the squirrel looks at the nut then at the tree trunk and then back at the nut. He interprets this as the squirrel cognitively considering two alternatives, then forming an intention to act, then acting. This two step process is evidence of an executive tier of mental control of behavior.

I have a young cat who does something similar. Winston knows there is interesting stuff happening on the counter when I’m making coffee. I see him looking at me, then at the counter as if contemplating jumping up. Am I paying attention to him? If I say No in a loud voice, he won’t jump. Maybe. But if I do nothing or am not paying attention, he works out an answer and acts.

Winston also knows how to open a door. Here’s a video of cats opening doors. Note that in several of the scenes the cat stares at the handle before acting. Tomasello interprets this as the cat forming an intention and then acting on the intention. Again, that implies an executive tier of mental activity.

Here’s a video of squirrels hiding nuts. Nut-hiding is a hard-wired activity, but it’s a complex problem. The squirrel has to decide where to bury the nut, and it has to be able to find it in winter. There are other squirrels waiting to steal the nuts, and predators. There are obstacles, including roots and hard soil. The squirrels stop and look around several times. In each case it looks like the squirrel makes a choice.

This is a 20 minute video of a guy operating a squirrel maze in his back yard. It’s not exactly relevant, but it looks like the squirrels are playing, something we don’t see lizards do. Also I enjoyed it.

The difference

Tomasello says that when lizards perceive a change in the situation, they freeze their current behavior and then respond to the new situation. He contrasts this chain of go/no go decisions with

… an either-or process of decision-making in which the individual simultaneously considers more than one behavioral option simultaneously (which mammals arguably do….) Pp. 33-4.

Tomasello says squirrels and other small mammals have an executive tier in their psychological processes that controls their operating behaviors, like running and burying nuts. This is a function of their larger brains, especially a larger pre-frontal cortex, more complex neurons and neural connections, and increased memory. Larger brains and longer time spent as juveniles increase the possibility of learning about the environment and experimenting, including play, which we might see as rehearsal. Mammals seem to have whet we would call emotions that also provide input to the executive tier.

The executive tier of the squirrel brain coordinates all these inputs. It considers alternative courses of action, “weighs” the costs and anticipated benefits of each and chooses one. That choice is communicated to the operant systems. The executive tier monitors the outcomes. It can inhibit one choice in favor of another if the situation changes or if the initial choice meets an obstacle or fails. Small mammals don’t use words, so it does this with some from of remembered perception.

Here’s Tomasello’s version of an executive tier:

The executive tier oversees the operational tier, as it were, and attempts to facilitate behavioral decisions via action planning and cognitive control. … It requires individuals to cognitively simulate in an organized way their own potential actions, the potential obstacles and opportunities for those actions, and the probable outcomes of those actions. They do this by perceptually imagining all these action elements in the common cognitive workspace and representational format provided by an executive tier of operation. P. 49.

It is this executive tier that gives mammals a wider range of choices of action, which presumably increases the chances of survival of individuals.


1. Tomasello says that there isn’t any way to find mental processes in brains, so scientists infer the mental processes from the overt behavior of the creature. I think this raises the potential of anthropomorphism, leading people to ascribe human characteristics to other kinds of creatures. The executive function in humans is a defining feature of our species, so this is a real possibility.Of course, here we’re talking about a simple form of executive control.

The videos seem to provide at least some reason to think Tomasello is on the right track in ascribing an executive tier to small mammals. The empirical studies he cites may also be persuasive evidence.

2. I have described only a small part of Chapters 3 and 4 for this post. It’s allfascinating, especially the discussion of the executive tier, but it’s not relevant to my purposes in reading this book. As a reminder, this series is aimed at thinking about the origins and roles of rights in our society. I’ll get there, I promise.

27 replies
  1. John Paul Jones says:

    I wonder if Tomasello has anything to say about corvids? Some have shown an ability to solve two-step problems in order to get food, that is, releasing a tool from a transparent box, which tool then has to be used to open a second transparent box containing the reward.

    • John Paul Jones says:

      Just went back and watched all of the squirrel video. What a hoot! Thanks for linking that. I’ve always believed that mammals at least have memory, intention, and adaptability, i.e., dogs, who watch us all the time for cues. What I liked about the squirrel video was the individuality of the four squirrels, that is, the range of possible adaptive behaviours allowing them to learn from each other.

  2. earlofhuntingdon says:

    Eats, shoots, leaves. :-) Thanks, Ed.

    To note a side of evolution humans tend to avoid, the forest floor and guts of predators are littered with the skeletons of squirrels who made bad executive decisions. It illustrates a how a species as a group is constantly shaped by eliminating individuals whose choices fail.

    Socially, Neoliberals and Social Darwinists, of course, tend to praise this aspect of biological evolution, to justify their own ruthless selfishness toward members of their own species (and the environment generally). That has the effect of rewarding and expanding their selfishness, unless and until opposition to it rises sufficiently to overcome the protective measures (laws, physical power) they have otherwise built into society.

    • Ed Walker says:

      Here you go:

      Once again I will not be considering species that branched off from reptiles in nonhuman directions, some of whom display great intelligence and agency. Of most importance are birds of the corvid and psittacine families (crows, jays, parrots, etc.). They have almost certainly evolved skills of executive control similar to those in mammals, presumably in a process of parallel evolution, but that is a story for someone else to tell.

      Tomasello, Michael. The Evolution of Agency (p. 44). MIT Press. Kindle Edition.

  3. Legonaut says:

    Mrs. Lego and I have housed a variety of fish and lizards over the years (two iguanas, a gecko, and now a bearded dragon). From long-term observation, I would have to nitpick with Tomasello; the lizards of my experience certainly seem to demonstrate an “executive tier” he would reserve for mammals. (Goldfish eating themselves to death might have been a better example.) That’s not to say the idea of an executive tier is a bad one, just that it can be surprisingly difficult to identify or rule out in animals (or even some humans, for that matter).

    BTW, the same YouTuber with the squirrel maze videos, Mark Rober, has a recent video about octopi intelligence that I found relevant and fascinating: https://www.youtube.com/watch?v=7__r4FVj-EI

  4. Roger Mexico says:

    This is shockingly close to my former area of expertise (recovering academic). I’ll confess that I have not read the book so I’ll spout a couple of generalities and slink away to take any appropriate beating.

    The suggestion that we can’t find any mental processes in brains is strictly true for what it’s worth. We can identify specific neural substrates associated with both stimulus-response type processing (attributed to lizards here) and volitional responding. There is solid work looking at competing S-R stimuli and behavioral output (shout out to leech locomotion and the “decision” to crawl or swim for the reductionists out there). We can also manipulate internal variables to affect volitional responding (specific satiety would be a good search term here). And we know quite a bit about the interactions of the systems (Pavlovian to instrumental transfer is a good search term here). So the issue is not a lack of understanding of the neural substrates or the associated neuronal activity, the failure tends to be on the looseness of the term “mental process”. We know what is happening, and how it’s coded, but we can’t know what the animal is “thinking” because we have never adequately defined “thought”.

    One other piece – these systems don’t exist in a binary state where we are doing S-R responding or executive level volitional responding. Most behaviors are a blend of the two with different aspects of the behavior being handled by the systems simultaneously. Driving is a great human example where there are multiple systems operating to produce a simple behavioral output.

    • Ed Walker says:

      Thanks for this. I’m a recovering lawyer myself, so this is well outside my field of formal training and experience. One big problem for the lay reader in these books is evaluating the evidence presented by the author. I can’t really do that though I did read several of the papers related to the later chapters, and plan to read more. I always appreciate expert help and explanation.

      The part you address tries to summarize this passage:

      Natural selection operates only on what it can “see,” and that is the organism’s overt actions (and its physical body as adapted for actions and other adaptive functions). The underlying psychological processes organizing and generating actions are thus naturally selected, but only indirectly through their effects on action. If an organism is capable of performing an action but does not perform it, that capability cannot become a target of natural selection. If an organism is motivated for an action but does not perform it, that motivation cannot become a target of natural selection. Analogously, scientists infer psychological processes from their effects on the organism’s overt actions. (The qualifier overt distinguishes the current approach from the “basal cognition” approach, in which all organismic functions, including bodily maintenance functions, are considered to be cognitive because they involve information processing; e.g., Lyon et al., 2021; Keijzer, 2021.)

      Tomasello, Michael. The Evolution of Agency (p. 27). MIT Press. Kindle Edition.

      I read this to say that we cannot identify a specific location in the brain for a structure Tomasello would identify as the executive tier. Instead, we infer the existence of the psychological process he calls an executive tier from the observable behavior of the creature.

      Thanks for taking the time to explain how much we can actually see in other creatures.

  5. Datnotdat says:

    First, thanks for your writing here.
    Second, C. Eligans has methods of sensing, and methods of reacting to their environment. They move toward nutrient gradients and a way from toxin gradients. No thing survives by having food fall in its mouth. So don’t sleep on C. Eligans!

    Third, about lizards. All animals, “down” to reptiles share the same mechanisms for reproduction. Humans like to daydream about their sexual activity, using lions, or horses, or wolves as their stand-ins. I wonder if envisioning lizards instead of mammals in our sexual daydreams could tell us anything additional about our “animal desires” or if it only tells us about our self-conception.

    • ExRacerX says:

      “Third, about lizards. All animals, ‘down’ to reptiles share the same mechanisms for reproduction.”

      Not so. There are many lizards that can reproduce asexually, including my local favorite, the New Mexico Whiptail, but no mammal can do so. Talk about self-conception!

      The bestiality angle, fantasy or otherwise, is in extremely poor taste.

    • Kick the Darkness says:

      There’s also mating behavior in C. elegans, which is clearly goal directed and involves a complex sequence of sub-behaviors. Although to what extent that entails what a human mind might consider cognizance or agency in pursuit of that goal, who knows.

      In an tour de force, researchers have recently globally mapped individual neuron activity throughout the brain in C.elegans during the mating sequence. The paper is called “Natural sensory context drives diverse brain-wide activity during C. elegans mating”-not behind a paywall.

      • Rayne says:

        A citation is preferred even if the content is paywalled.

        Vladislav Susoy, Wesley Hung, Daniel Witvliet, Joshua E. Whitener, Min Wu, Core Francisco Park, Brett J. Graham, Mei Zhen, Vivek Venkatachalam, Aravinthan D.T. Samuel,
        Natural sensory context drives diverse brain-wide activity during C. elegans mating,
        Cell, Volume 184, Issue 20, 2021, Pages 5122-5137.e17, ISSN 0092-8674,

        • Kick the Darkness says:

          Thanks. I know people are particular around here at to the way in which links are posted, and didn’t know the ins or outs.

          • Rayne says:

            Even a link alone would be sufficient, perhaps better than an article/paper title given how bad Google has become thanks to poisoning with AI-formulated content and results.

            • Kick the Darkness says:

              OK. Since on it, are there concerns here about outside links…I seem to remember issues surrounding links coming up from time to time in the past. If not, my bad.

              • Rayne says:

                If you use an active link in a comment during late evening/early morning hours US time, you may have to wait for volunteer moderators to clear the comment.

                If you deactivate the link by inserting blank spaces like so — https :// www. linkaddress. com — the post will likely clear moderation assuming there are no trigger words in the comment and no typographical errors in username/email address.

    • Ed Walker says:

      I refuse to state how many hours I spent watching videos for this post. I will say that my spouse has gotten big laughs about it at dinner parties.

      • Kick the Darkness says:

        I wonder if Tomasello has ever tried to squirrel proof bird feeding stations. At some point I admitted I had been defeated and now buy cracked corn that I scatter at the base of the feeders. But there’s always that one that refuses to be a kept squirrel, and goes through all kinds of gymnastics to get on the feeders..maybe, just maybe….to show they can. Enjoying this series-thank you.

  6. bgThenNow says:

    I also have a young cat named Winston, who I call Winnie. He runs my life. I have one trick–treats. He will do just about anything for those. I keep them in the refrigerator now because he learned to open the cabinet where they were previously kept. Now when he hears the door to the refrigerator open, he jumps up and stands in the open door. I have never had a cat more motivated by treats. I believe he understands the word NO, but whether he responds as I intend is another story. He comes from wherever he is if I shake the treats container. Otherwise my power is limited. I’m reading Eve, about the evolution of female reproduction. I believe we are a failed species.

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