The Self-Made Human Brain
Being Human 101: Science has discovered that the human brain is a workaholic.
Posted Oct 16, 2020
The neurologist Marcus Raichle has remarked that studies of brain function have traditionally focused on task-evoked responses (Raichle 2010, 2015). As Daniel Kahneman has explained, such research has contributed the useful convention that there are two modes of thinking—two systems in the mind, System 1 (or Type 1) and System 2 (or Type 2). In Kahneman’s words (2011: 20–21):
System 1 operates automatically and quickly, with little or no effort and no sense of voluntary control.
System 2 allocates attention in the effortful mental activities that demand it, including complex computations. The operations of System 2 are often associated with the subjective experience of agency, choice, and concentration.
Although such conventions are useful, Raichle argues that focusing on task-evoked responses “ignores the alternative possibility that brain functions are mainly intrinsic, involving information processing for interpreting, responding to and predicting environmental demands” (2010: 180).
As he says, it is not difficult to see why so much attention has been given to monitoring neural responses to carefully designed tasks that can be rigorously controlled: “Evaluating the behavioral relevance of intrinsic activity (i.e. ongoing neural and metabolic activity which is not directly associated with subjects’ performance of a task) can be an elusive enterprise” (2010: 180).
While it could be argued that intrinsic brain tasks are part and parcel of System 2 thinking, I believe it may be more constructive to infer instead that there is a third mode of thinking—one that I have suggested may be called cognitive niche construction (Terrell 2015: 29–32, 168–172) — a way of thinking that may strongly engage the brain’s default-mode network.
As Raichle (2015), as well as Robert Spunt and his colleagues (2015), have underscored, there is a considerable metabolic cost to running the human brain when it is engaged in ongoing internal activity. As the latter researchers observe: “Most of the brain’s energy budget is consumed not by activity evoked by specific cognitive tasks (e.g., mental arithmetic) but by spontaneous ongoing activity that is most notable when the brain is at rest.”
Zalán Rajna et al. (2015) / Wikipedia Commons / public domain
Given the metabolic cost of this ongoing internal activity in what has been dubbed the brain’s default mode network (DMN) when we are not task-engaged, an obvious question arises. How can we afford such stimulus-independent activity?
Raiche, Spunt et al., and others stress the likelihood that such inner-directed brain activity must be somehow adaptive in a realistic Darwinian sense, i.e., this inner activity must be “functionally consequential for the execution of stimulus-dependent mental state inferences” (Spunt et al. 2015: 1122). This inference is plausible, but arguably not sufficient.
How we are able to remake the world around us when we put our minds and backs to the effort has been called niche construction (Odling-Smee et al. 2003). In the biological sciences, the word “niche” means “way of life,” and every species is said to have its particular place, or niche, in the economy of life. We are just one of a number of species that excel at making and remaking their way of life, their place in the grand scheme of things, their ecological niche. Similarly, I have argued that even when it may look as if we are daydreaming, our minds actually may be hard at work engaged in cognitive niche construction — a way of using our brains that is possibly but not necessarily unique to our species (Terrell 2015).
Others recently have also written about cognitive niche construction, but what they evidently have in mind may be more clearly activity under the heading of System 2 thinking. Steven Pinker, for instance, has defined cognitive niche construction as “a mode of survival characterized by manipulating the environment through causal reasoning and social cooperation” (Pinker 2010: 8993).
Such a description glosses over how difficult it can be to apply what we envision in our mind’s eye to the realities of life. More to the point, such a definition does not confront the obvious weakness of cognitive niche construction at least as I have described it. What goes on between our ears when we are engaged in such mental activity does not have to be rational at all, at least not if by “rational” we mean thinking that makes practical sense in the real world outside our bodies.
By detaching from the realities of the moment and turning our mind to our inner thoughts, we are able to ponder what I like to call the coulds and shoulds of life. We can devote our mind to a kind of imaginary niche construction that does not even have to be “of this world” at all. We can see seemingly impossible things in our mind’s eye. We can engage in “what if” fantasies of remarkable, perhaps sexually charged, and even quite unrealistic complexity. We can invent imaginary worlds, invent new things, rewrite the story of our life to our heart’s content. All in the mind rather than in the real world.
In short, it seems likely we engage in cognitive niche construction not just for interpreting, responding to, and predicting environmental demands—to paraphrase what Raichle has previously said. As Spunt et al. observe: “Given that the DMN activity is metabolically costly, widely distributed in the cortex, and highly sensitive to both the presence and type of task demand, it should be no surprise that this network would have functional consequences in multiple domains” (Spunt et al., 2015: 1122).
They themselves hypothesize that natural selection has favored the evolution of such a costly DMN in humans (and possibly also in chimpanzees and monkeys) so that we can more skillfully “see the world in terms of other minds” and live together socially — thereby gaining far more socially than would be likely by living separately.
While this is a plausible hypothesis, it is not the only one possible ...
Note: This commentary, which was the first in a series, was also published on Science Dialogues, a blog site that has now vanished into the Great Blog Bog in the Sky.
Next up — Dogs, Cats, and the Myth of Human Superiority
Kahneman, Daniel (2011). Thinking: Fast and Slow. New York: Farrar, Straus and Giroux.
Odling-Smee, F. John, Kevin N. Laland, and Marcus W. Feldman (2003). Niche Construction. Princeton: Princeton University Press.
Rajna, Zalán, Janne Kananen, Anja Keskinarkaus, Tapio Seppänen, and Vesa Kiviniemi (2015). Detection of short-term activity avalanches in human brain default mode network with ultrafast MR encephalography. Frontiers in Human Neuroscience 9: 448.
Terrell, John Edward (2015). A Talent for Friendship: Rediscovery of a Remarkable Trait. Oxford and New York: Oxford University Press.