Diachronic semantic change in language influences, and is constrained by, how people use and learn language

Abstract

It has long been understood that the mind has evolved to learn language. Recently this claim has been inverted to question how language evolves to become learnable. However, there is little evidence on how semantic evolution is shaped by language acquisition and processing in a naturally occurring language. In this research, we provide evidence to demonstrate how the human mind and language evolution of semantic constraint one and other. In study 1, we showed that words that people found more difficult to learn and process changed their semantics at a higher rate over the past 200 years, suggesting human cognition constrains semantic evolution. The alternative causality of study 1 is that semantic change since 1800 leads to difficulty in learning and processing. This alternative is unlikely because knowledge unknown to people living today, that is, historical meanings of words before their birth, could not influence how people learn and process language. However, semantic change, if occurred in recent decades, could in turn hamper semantic processing, but only for those people who were born early enough to experience it. We found supporting evidence in study 2 that semantic change between 1970 and 2000 hinders the processing speed in middle-aged adults (aged 45-55) but not in younger adults (aged <25). Taken together, our two studies highlight the importance of studying language evolution in relation to processing and acquisition patterns across generations of language users.