"Dog Leash, Dog, Woman" by bravor1x / Pixabay / CC0 Public Domain
Source: "Dog Leash, Dog, Woman" by bravor1x / Pixabay / CC0 Public Domain

During the numerous talk show appearances that Hamilton creator and star Lin Manuel Miranda regularly makes, he is virtually always asked to demonstrate his prowess as a freestyle rapper. On two separate appearances on Jimmy Fallon’s Tonight Show, for example, he participated in a game called “Wheel of Freestyle,” in which he was required to work 3 spontaneously generated random words (e. g. rainbow, pancake, and slam dunk) into a freestyle rap. Throughout his long succession of talk show freestyling appearances, the bard of Hamilton never fails to “rise up” to the occasion.

To fully appreciate the achievement of routinely pulling off such spontaneous verbal virtuosity on command, it is important to point out that the word “freestyle” is something of a misnomer.  While it is “free” in the sense that it is spontaneously created, it is nonetheless constrained by a number of factors such as rhythm, rhyme, and, in the case of “Wheel of Freestyle,” word choice. It is not the free, spontaneous generation of meaningful sequences of phrases and sentences that sends talk show hosts like Jimmy Fallon into paroxysms of gleeful admiration, but rather the constraints under which Miranda must generate these meaningful verbal sequences. 

The interaction between freedom and constraint in poetry composition—freestyle or otherwise—has long been noted. Writing in the first century A. D., the Greek literary critic Longinus said of poetical composition that “greatness needs the spur often; it also needs the bit.” Anyone who has ever seriously tried to write a poem (particularly a “traditional” form such as a sonnet or a ballad) will know what that bit feels like.

Poetry composition is, of course, not unique among creative endeavors in embodying this balancing act between freedom and restraint.  Any meaningful act of creativity in any domain—from music, to visual art, to science and mathematics—involves an exercise of freedom within a system of constraints.  As fundamental to creativity as this principle has long been considered, its operation within specific acts of creation has until recently been largely based on anecdotal evidence. Recent neuroimaging research, however, has made it possible to see this interplay between freedom and restraint at work in the brains of people engaged in various acts of creativity.  Much of this research has focused on the interaction between two distinct, and often competing, brain networks—the default network and the executive control network.

The default network, comprising “midline and posterior inferior parietal regions that show increased metabolic activity in the absence of most externally presented cognitive tasks,” is most active when the brain is “at rest” in the sense that it is not actively engaged in a task that requires focused attention. Sometimes called the “mind-wandering” network, the default network is involved in “spontaneous and self-generated thought” such as mental simulation, retrieval of autobiographical memories, and projections of future events. The executive control network, comprising “lateral prefrontal and anterior inferior parietal regions,” is involved in cognitive processes that “require externally directed attention.” Any task that demands your full concentration--from remembering a phone number, to working a Calculus problem, to pulling a block from a Jenga tower—engages your executive control network.

The default and the control networks are most often in competition with each other. When we are engaged in an external task that requires our full attention, it is our executive control network that keeps our minds from wandering off of that task to memories of yesteryear or dreams of tomorrow.  On the other hand, when our mind is on full wandering mode drifting hither and yon wherever the neural wind blows it, the executive control network is offline and it takes an act of supreme willpower to engage it once again to focus our attention on an external task.  In stark contrast to their typically antagonistic relationship, however, during activities that require creative thinking the default and control networks of the brain actually appear to work together.

Several recent studies have used whole brain functional connectivity analysis to assess dynamic interactions between brain regions during creative activities including musical improvisation, visual art, creative writing, and lyrical improvisation (such as freestyle rap). In each of these studies, acts of creative thinking were accompanied by increased functional connectivity between regions of the brain involved in the default network and those involved in the control network. Other studies exploring creative thinking not tied to a specific domain (e. g. alternative usage tasks, where people are asked to think of novel and appropriate uses for common objects), showed a similar coupling between default and control networks.

Researchers conclude from these results that creative thinking is a two-stage process comprising idea generation, a “bottom-up process associated with diffuse attention,” and idea evaluation, a top-down process involving “focused attention and cognitive control.” In other words, during an act of creation, the default network combines elements of our memory in novel ways to “generate candidate ideas,” and our control network constrains and directs this generation process to meet the demands of whatever “task-specific goals” may be in play.

This neural network cooperation is clearly evident on The Tonight Show’s “Wheel of Freestyle.” When Lin Manuel Miranda is presented with the words “dinosaur, pumpkin pie, and Darth Vader,” his brain’s default network rifles through his memory for facts, experiences, and images that have some tenuous connection with the presented words, and his control network evaluates the semantic relevance of these ideas to the word list and to each other, while at the same time arranging the generated ideas in ways that fulfill the syntactical, metrical, and rhyming constraints of the task. And all of this takes place in the span of about ninety seconds. It’s no wonder that Jimmy Fallon is blown away with astonishment.