<i>Like sentences, the catalogue of human actions is infinite. We stretch, bend, and kick. We build bridges and prepare meals. We perform an endless variety of dance routines. We make paper airplanes. A complex action, like hammering a nail, can be broken down into its constituent actions – grasping, striking, reaching – just as a sentence can be broken into its units – nouns, verbs, adjectives. In 1951, cognitive psychologist Karl Lashley proposed a link between language and action. "Not only speech,” he wrote, “but all skilled acts seem to involve the same problems of serial ordering, even down to the temporal coordination of muscular contractions in such a movement as reaching and grasping." Just as a stream of speech does not contain explicit pauses between words, fluid actions like nail hammering do not contain breaks between their components. Yet humans effortlessly parse speech streams and action sequences into their parts.</i><p>I've found this part most interesting. I wonder if it's just the general pattern matching at work or something more.