This week, a woman was strolling in my street, walking in circles and speaking out loud to herself. People were looking at her awkwardly, but she didn’t particularly mind, and continued walking vigorously and speaking.

Yes, that woman was me.

Like many of us, I talk to myself out loud, though I’m a little unusual in that I often do it in public spaces. Whenever I want to figure out an issue, develop an idea or memorise a text, I turn to this odd work routine. While it’s definitely earned me a reputation in my neighbourhood, it’s also improved my thinking and speaking skills immensely. Speaking out loud is not only a medium of communication, but a technology of thinking: it encourages the formation and processing of thoughts.

The idea that speaking out loud and thinking are closely related isn’t new. It emerged in Ancient Greece and Rome, in the work of such great orators as Marcus Tullius Cicero. But perhaps the most intriguing modern development of the idea appeared in the essay ‘On the Gradual Formation of Thoughts During Speech’ (1805) by the German writer Heinrich von Kleist. Here, Kleist describes his habit of using speech as a thinking method, and speculates that if we can’t discover something just by thinking about it, we might discover it in the process of free speech. He writes that we usually hold an abstract beginning of a thought, but active speech helps to turn the obscure thought into a whole idea. It’s not thought that produces speech but, rather, speech is a creative process that in turn generates thought. Just as ‘appetite comes with eating’, Kleist argues, ‘ideas come with speaking’.

A lot of attention has been given to the power of spoken self-affirmation as a means of self-empowerment, in the spirit of positive psychologyContemporary theories in cognition and the science of learning reaffirm Kleist’s speculations, and show how self-talk contributes not only to motivation and emotional regulation, but also to some higher cognitive functions such as developing metacognition and reasoning.

If self-talk is so beneficial, why aren’t we talking to ourselves all the time? The dynamic between self-talk and inner speech might explain the dubious social status of the former. Self-talk is often seen as the premature equivalent of inner speech – the silent inner voice in our mind, which has prominent cognitive functions in itself. The tendency to express our inner thoughts in actual self-talk, typical of children, is internalised, and transforms to voiceless inner speech in adulthood, as the developmental psychologist Lev Vygotsky already speculated in the 1920s.

Vygotsky’s view stood in opposition to a competing one from the psychological school known as behaviourism, which saw children’s self-talk as a byproduct of (supposedly) less competent minds.