The idea that natural language is shaped by biases in learning plays a key role in our understanding of how human language is structured, but its corollary that there should be a correspondence between typological generalisations and ease of acquisition is not always supported. For example, natural languages tend to avoid close repetitions of consonants within a word, but developmental evidence suggests that, if anything, words containing sound repetitions are more, not less, likely to be acquired than those without. In this study, we use word-internal repetition as a test case to provide a cultural evolutionary explanation of when and how learning biases impact on language design. Two artificial language experiments showed that adult speakers possess a bias for both consonant and vowel repetitions when learning novel words, but the effects of this bias were observable in language transmission only when there was a relatively high learning pressure on the lexicon. Based on these results, we argue that whether the design of a language reflects biases in learning depends on the relative strength of pressures from learnability and communication efficiency exerted on the linguistic system during cultural transmission.

自然语言受学习偏见影响的观点在我们对人类语言结构的理解中起着关键作用，但并非总是支持类型学概括和易学性之间的对应关系。例如，自然语言倾向于避免单词中辅音的紧密重复，但是发展证据表明，包含声音重复的单词（如果有的话）比没有单词的单词更容易获得。在这项研究中，我们使用单词内部重复作为测试案例，以提供文化演化的解释，说明何时以及如何学习偏向对语言设计的影响。两项人工语言实验表明，成年说话者在学习新颖单词时，在辅音和元音重复方面都有偏见，但是只有在词汇学习压力较高的情况下，这种偏见的影响才能在语言传播中被观察到。根据这些结果，我们认为语言的设计是否反映了学习中的偏倚取决于文化传播过程中施加于语言系统的学习能力和沟通效率所带来的压力的相对强度。