The chicken and the egg: unraveling aspects of semantic change and how they relate to lexical acquisition.

Several recent studies have shown intricate correlations between semantic change and the age of acquisition (AoA) of words, thus reviving the long-standing debate about the relationship between language acquisition and language change, both of which can express weak cognitive biases. However, semantic change can occur in various ways. In this paper, we aim to disentangle different aspects of semantic change and test its relationship to AoA. Specifically, we operationalize semantic change using three different and complementary measures: wiggliness, i.e., a word's tendency to show short-term semantic fluctuation; displacement, i.e., the long-term shift that a word's meaning displays; and diversification, i.e., the degree of polysemy that a word assumes over time. A regression analysis, in which we control for frequency effects, reveals that the three measures of semantic change are associated with AoA, but in opposing ways. Early acquisition is associated with low wiggliness (in particular if frequency is high) and low displacement, but high diversification. Based on a pseudo-causal follow-up analysis involving Bayesian networks, we argue that while early acquisition unidirectionally demotes long-term semantic displacement, there must be a circular 'chicken-and-egg' relationship between lexical acquisition and semantic wiggliness and diversification. Differential cognitive mechanisms are necessary to account for these relationships.