On the replicator dynamics of lexical stress: accounting for stress-pattern diversity in terms of evolutionary game theory

Abstract

This paper accounts for stress-pattern diversity in languages such as English, where words that are otherwise equivalent in terms of phonotactic structure and morphosyntactic category can take both initial and final stress, as seen in ˈlentil–hoˈtel, ˈenvoy–deˈgree, ˈresearchN–reˈsearchNand ˈaccessV–acˈcessV. Addressing the problem in general and abstract terms, we identify systematic conditions under which stress-pattern diversity becomes stable. We hypothesise that words adopt stress patterns that produce, on average, the best possible phrase-level rhythm. We model this hypothesis in evolutionary game theory, predict that stress-pattern diversity among polysyllabic word forms depends on the frequency of monosyllables and demonstrate how that prediction is met both in Present-Day English and in its history.

Prevocalic t-glottaling across word boundaries in Midland American English

“…Seyfarth (2014) found that durations of words which are typically predictable from their immediate context (e.g., current) are reduced more than durations of words which are typically less predictable from their immediate context (e.g., nowadays), even when a particular instance of the typically predictable word (e.g., current) is not, in fact, predictable. Baumann and Ritt (2017) show that the development of the link between morphosyntactic category and word stress in English of the ˈresearch -reˈsearch type can be modeled by assuming that lexical stress is an accumulation of repeated adaptations to phrase-level rhythm. Eddington and Channer's (2010) finding poses another serious challenge to 'abstract only' models.…”

Replicator–mutator dynamics of linguistic convergence and divergence

“…In [31], for example, the fitness of strategies (competing form-meaning mappings) results from a combination of communicative success and formal linguistic economy. In [33], on the other hand, strategies constitute competing stress placements on lexical items (the 'players' of the game) and fitness results from eurhythmicity (or lack thereof) at the level of entire phrases. It should be noted that the notion of fitness is by no means new to linguistics, but rather, the above interpretations are related in obvious ways to traditional accounts of the differential adaptedness of linguistic variants, ranging from communicative function and contrast maintenance [41,42] through prestige and other kinds of social biases [20,43] to parsing advantage [44,45] and economy of computation, perception or articulation [46,47].…”

“…One advantage of EGT-based modelling over other approaches, such as agent-based simulations, is that analytical results can often be obtained if the assumptions entering the game’s definition are suitably abstract. This renders EGT models transparent [ 33 ], as the complete phase space of the model can be succinctly characterized, along with any possible bifurcations the system may undergo in response to variation in its control parameters. Even when analytical tractability is lost, macro-level dynamical-systems modelling has the advantage that the numerical solution of the relevant differential equations is considerably less resource-intensive than the computer simulation of corresponding agent-based models.…”

“…In very general terms, the shape of equation ( 2.1 ) implies that the usage of a strategy increases (decreases) whenever its fitness is greater (lower) than that of its competitor. The replicator equation can thus serve as a basic formalization of Darwinian selection [ 37 ], but crucially for applications in cultural evolution, it can also be interpreted as describing the differential replication of non-biologically transmitted variants [ 33 , 34 ]. As a continuous-time differential equation, it formally describes the evolution of strategies in a hypothetical infinite, fully mixing population.…”

“…A number of applications of evolutionary game-theoretic (EGT) modelling are now available in the literature on language dynamics [26][27][28][29][30][31][32][33][34][35]. These will be briefly discussed in Section 2 in order to contextualize the contribution of the present paper.…”