Languages are efficient, but for whom?

• Published in: Cognition Vol. 225; p. 105094
• Main Authors: Trott, Sean, Bergen, Benjamin
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.08.2022; Elsevier Science Ltd
• Subjects: Ambiguity; Cognitive ability; Communication; Efficiency; Frequency; Homophones; Humans; Individual differences; Language evolution; Meaning; Pressure; Reuse; Frequency; Homophones; Efficiency; Language evolution; Ambiguity
• ISSN: 0010-0277; 1873-7838; 1873-7838
• DOI: 10.1016/j.cognition.2022.105094

Human languages evolve to make communication more efficient. But efficiency creates trade-offs: what is efficient for speakers is not always efficient for comprehenders. How do languages balance these competing pressures? We focus on Zipf's meaning-frequency law, the observation that frequent wordforms have more meanings. On the one hand, this law could reflect a speaker-oriented pressure to reuse frequent wordforms. Yet human languages still maintain thousands of distinct wordforms, suggesting a countervailing, comprehender-oriented pressure. What balance of these pressures produces Zipf's meaning-frequency law? Using a neutral baseline, we find that frequent wordforms in real lexica have fewer homophones than predicted by their phonotactic structure: real lexica favor a comprehender-oriented pressure to reduce the cost of frequent disambiguation. These results help clarify the evolutionary drive for efficiency: human languages are subject to competing pressures for efficient communication, the relative magnitudes of which reveal how individual-level cognitive constraints shape languages over time.