Iterated language learning experiments have shown that meaningful and structured signalling systems emerge when there is pressure for signals to be both learnable and expressive. Yet such experiments have mainly been conducted with adults using language-like signals. Here we explore whether structured signalling systems can also emerge when signalling domains are unfamiliar and when the learners are children with their well-attested cognitive and pragmatic limitations. In Experiment 1, we compared iterated learning of binary auditory sequences denoting small sets of meanings in chains of adults and 5-7-year old children. Signalling systems became more learnable even though iconicity and structure did not emerge despite applying a homonymy filter designed to keep the systems expressive. When the same types of signals were used in referential communication by adult and child dyads in Experiment 2, only the adults, but not the children, were able to negotiate shared iconic and structured signals. Referential communication using their native language by 4-5-year old children in Experiment 3 showed that only interaction with adults, but not with peers resulted in informative expressions. These findings suggest that emergence and transmission of communication systems is unlikely to be driven by children, and point to the importance of cognitive maturity and pragmatic expertise of learners as well as feedback-based scaffolding of communicative effectiveness by experts during language evolution. Language transmission in adults and children 3 Introduction Languages are shaped by two sets of constraints: the need to be learnable so they can be transmitted to the next generation, and the need to be expressive to ensure successful communication (Tamariz, 2017). Empirical evidence for this insight comes from experimental semiotics studies of novel signalling systems (Garrod & Galantucci, 2011) which comprise iterated language learning experiments, where the outcome of learning a mini-language by one participant serves as input for the next participant in a chain (Cornish, Smith & Kirby, 2013; Cornish, Dale, Kirby & Christiansen, 2017; Kirby, Cornish & Smith, 2008; Kirby, Tamariz, Cornish & Smith, 2015; Silvey, Kirby, and Smith, 2014; Verhoef, Kirby & Padden, 2011; Verhoef, 2012; Verhoef, Kirby & de Boer, 2014; 2016; Verhoef, Roberts & Dingemanse, 2015), as well as referential communication tasks and signalling games, where multiple participants negotiate meanings of novel signals over several rounds of communicative interaction (Dingemanse, Blasi, Lupyan, Christiansen & Monaghan, 2015; Fay, Ellison & Garrod, 2014; Garrod, Fay, Lee, Oberlander & MacLeod, 2007; Roberts et al., 2015, Selten & Warglien, 2007). These studies have shown that unstructured stimuli become increasingly easier to learn and to use because innovations are shaped by learners’ implicit biases towards simpler, more transparent (Jones, Vinson, Clostre, Zhu, Santiago & Vigliocco, 2014; Dingemanse et al., 2015; Roberts et al., 2015) and more compressible (Kirby, Griffiths & Smith, 2014; Tamariz & Kirby, 2015; 2016 Xu & Griffiths, 2010) languages. To date, these types of laboratory experiments have been conducted mainly with adults. It is conceivable that adults, especially when presented with language-like signals, albeit artificial ones, will invoke their considerable meta-linguistic knowledge about what language ought to be like. Yet language is primarily acquired by children who lack this metalinguistic knowledge and are subject to a range of cognitive constraints that differ from those operating in adults. To gain a better understanding of the generalisability of findings from experimental semiotics, and to explore the role of the cognitive and pragmatic constraints imposed by child learners, this study compares transmission and creation of unfamiliar signalling systems between adults and children. To predict in what ways children may alter the way consistent and communicatively efficient signalling systems emerge we first need to consider what research in experimental semiotics tells us about how such systems emerge in adults. Language transmission in adults and children 4 The findings can be summarised with respect to three crucial features of language: iconicity, combinatorial structure and compositional structure. Iconicity emerges when adult learners are faced with novel signal-meaning mappings, and attempt to exploit transparent links between physical properties of the signals and dimensions of the associated meanings (Dingemanse et al. 2015; Roberts et al., 2015), capitalising either on abundant neonatal cross-modal connections or acquired knowledge about statistical regularities or cross-modal co-occurrences (Spence, 2011). Emergence of iconicity has been demonstrated not just when learners negotiate novel signalling systems during communication but also in simple iterated learning experiments without communication (Jones et al., 2014). Iconic signal-meaning mappings are subsequently aligned and refined during communicative interaction, resulting in conventionalised signals that become increasingly arbitrary (Garrod & Galantucci, 2011; Lister & Fay, 2017). Emergence of combinatorial structure can be demonstrated in iterated learning experiments with novel stimuli that are not linked to referents, e.g. whistle sounds (Verhoef, 2012; Verhoef et al., 2014; 2015), colour sequences (Cornish, Smith & Kirby, 2013), doodles (del Giudice, 2012; Tamariz & Kirby, 2015) or random dot patterns (Kempe, Gauvrit & Forsyth, 2015). As a result of iterations through consecutive cycles of learning, such meaningless stimuli become more systematic and structured as sub-components like pitch contour segments or small colour sequences are recombined to generate potentially unlimited sets, in the same way as phonemes are combined to form morphemes and words in natural languages. When such unfamiliar stimuli are linked to meaning, combinatorial structure can also arise from the pressure to minimise confusion between signals as an increase in the number of signals renders them increasingly difficult to discriminate (Nowak, Krakauer & Dress, 1999; Zuidema & deBoer, 2009), but also from intrinsic signal features such as rapid fading (Roberts & Galantucci, 2012), or limited iconic affordances of the signalling domain (Roberts, Lewandwoski & Galantucci, 2015). Compositional structure has been shown to emerge when the signals are not only subjected to iterated learning but also used to communicate meaning (Kirby et al., 2015), when meaning spaces undergo expansion (Selten & Warglien, 2007), when communication involves multiple interlocutors in social networks (Raviv, Meyer & Lev-Ari, 2019) or when context-based predictability of referents is low (Winters, Kirby & Smith, 2018). In these situations, sub-components of the signals become Language transmission in adults and children 5 systematically associated with dimensions of the meanings, akin to morpho-syntactic rules in natural languages (del Giudice, 2012; Kirby, Cornish & Smith, 2008; Kirby, Tamariz, Cornish & Smith, 2015; Silvey et al., 2014; Verhoef, Roberts & Dingemanse, 2015). In the present study we ask if and how these basic results would change when novel signals are learned and used by children. Children differ from adults with respect to cognitive capacities, pragmatic abilities, pre-existing real-world knowledge and prior linguistic experience. It is therefore important to investigate more directly how children create and transmit novel signalling systems in order to gain a better understanding of the underlying constraints operating in this process and the role that children may play in language change, especially in light of claims that diversity of linguistic structure is linked to the proportion of child vs. adult learners of a language and the differences in learning constraints this may impose on the process of language transmission (Lupyan & Dale, 2010; Dale & Lupyan, 2012). Predictions about what constraints children impose on the emergence of communicatively efficient signalling systems and in what ways these constraints differ from those imposed by adults should address both emergence of iconicity and emergence of structure. Findings from child language development research suggests that such predictions will not necessarily be straightforward: With respect to the emergence of iconicity, the Iconic Bootstrapping Hypothesis (Imai & Kita, 2014) proposes that children benefit from iconic signal-meaning mappings because such mappings are transparent and hence easier to comprehend thereby alleviating the burden of learning. Consequently, children should be more predisposed than adults to capitalise on transparent cross-modal associations between signal features and meaning dimensions. However, the developmental origins of transparent cross-modal association are not clear. A recent meta-analysis of the emergence of the kiki-boubaeffect in infancy and early childhood (Ford, Lammertink, Peperkamp, GuevaraRukoz, Fikkert & Tsuji, 2018) suggested that some cross-model correspondences (e.g. the bouba-effect which refers to the association of round shapes with back vowels and voiced consonants) are present early on while others (e.g. the kiki-effect which refers to the association of spiky shapes with front vowels and voiceless consonants) tend to emerge over time. This would lead to fairly complex predictions according to which some iconic mappings may be preferred by children while others should more easily accessible to adults based on their greater experience with statistical regularities in the Language transmission in adults and children 6 environment yet the literature at present does not allow us to make predictions with regards to specific age-dependent cross-modal preferences. Predictions are also inconsistent with respect to the emergence of structure. On the one hand, in accordance with the Less-Is-More-h

中文翻译：

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成人在创造和传输新的信号系统方面比儿童更有效

迭代语言学习实验表明，当信号既可学习又可表达时，就会出现有意义和结构化的信号系统。然而，此类实验主要是针对成年人使用类似语言的信号进行的。在这里，我们探讨了当信号域不熟悉以及当学习者是具有充分证明的认知和语用局限性的儿童时，结构化信号系统是否也会出现。在实验 1 中，我们比较了二进制听觉序列的迭代学习，这些序列表示成人和 5-7 岁儿童链中的小组含义。尽管应用了旨在保持系统表现力的同音异义过滤器，但信号系统变得更易于学习，尽管图像性和结构没有出现。在实验 2 中，当成人和儿童在参照交流中使用相同类型的信号时，只有成人，而不是儿童，能够协商共享的标志性和结构化信号。实验 3 中 4-5 岁儿童使用母语进行的参考交流表明，只有与成人的互动，而不是与同龄人的互动才能产生信息性表达。这些发现表明，交流系统的出现和传播不太可能由儿童驱动，并指出学习者的认知成熟度和实用专业知识以及专家在语言进化过程中基于反馈的交流有效性支架的重要性。成人和儿童的语言传播 3 引言 语言受到两组限制条件的影响：需要是可学习的，以便它们可以传递给下一代，并且需要具有表现力以确保成功的沟通（Tamariz，2017）。这种洞察力的实证证据来自新信号系统的实验符号学研究 (Garrod & Galantucci, 2011)，其中包括迭代语言学习实验，其中一个参与者学习一种迷你语言的结果作为链中下一个参与者的输入(Cornish, Smith & Kirby, 2013; Cornish, Dale, Kirby & Christiansen, 2017; Kirby, Cornish & Smith, 2008; Kirby, Tamariz, Cornish & Smith, 2015; Silvey, Kirby, and Smith, 2014; Verhoef, Kirby & Padden, 2011; Verhoef, 2012; Verhoef, Kirby & de Boer, 2014; 2016; Verhoef, Roberts & Dingemanse, 2015)，以及参考通信任务和信号游戏，多个参与者在几轮交流互动中协商新信号的含义（Dingemanse、Blasi、Lupyan、Christiansen 和 Monaghan，2015 年；Fay、Ellison 和 Garrod，2014 年；Garrod、Fay、Lee、Oberlander 和 MacLeod，2007 年；Roberts 等人., 2015, Selten & Warglien, 2007)。这些研究表明，非结构化刺激变得越来越容易学习和使用，因为创新是由学习者对更简单、更透明的内隐偏见塑造的（Jones、Vinson、Clostre、Zhu、Santiago 和 Vigliocco，2014 年；Dingemanse 等人，2015 年） ; Roberts et al., 2015) 和更可压缩的 (Kirby, Griffiths & Smith, 2014; Tamariz & Kirby, 2015; 2016 Xu & Griffiths, 2010) 语言。迄今为止，这些类型的实验室实验主要是针对成年人进行的。可以想象，成年人，尤其是在呈现类似语言的信号时，尽管是人工信号，但会唤起他们关于语言应该是什么样子的大量元语言知识。然而语言主要是由缺乏这种元语言知识的儿童获得的，并且受到与成人不同的一系列认知限制。为了更好地理解实验符号学研究结果的普遍性，并探索儿童学习者强加的认知和语用约束的作用，本研究比较了成人和儿童之间陌生信号系统的传播和创造。为了预测儿童可能以何种方式改变一致且有效的信号系统出现的方式，我们首先需要考虑实验符号学中的哪些研究告诉我们这些系统如何在成人中出现。成人和儿童的语言传播 4 研究结果可以概括为语言的三个关键特征：象似性、组合结构和组合结构。当成人学习者面临新的信号-意义映射，并试图利用信号的物理特性和相关意义的维度之间的透明联系时，就会出现标志性 (Dingemanse et al. 2015; Roberts et al., 2015)，利用丰富的新生儿跨模态连接或获得有关统计规律或跨模态共现的知识（Spence，2011）。不仅在学习者在交流过程中协商新的信号系统时，而且在没有交流的简单迭代学习实验中，象似性的出现都得到了证明（Jones et al., 2014）。标志性的信号-意义映射随后在交流互动中被对齐和完善，导致传统化的信号变得越来越武断（Garrod & Galantucci，2011；Lister & Fay，2017）。组合结构的出现可以在迭代学习实验中得到证明，这些刺激与指涉对象无关，例如哨声（Verhoef，2012；Verhoef 等，2014；2015），颜色序列（Cornish，Smith & Kirby，2013） 、涂鸦（del Giudice，2012 年；Tamariz 和 Kirby，2015 年）或随机点图案（Kempe、Gauvrit 和 Forsyth，2015 年）。作为通过连续学习循环进行迭代的结果，这种无意义的刺激变得更加系统和结构化，因为像音高轮廓段或小颜色序列这样的子组件被重新组合以生成潜在的无限集合，就像音素组合形成语素一样和自然语言中的词。当这种陌生的刺激与意义相关联时，由于信号数量的增加使它们越来越难以区分，组合结构也可能来自于尽量减少信号之间混淆的压力（Nowak，Krakauer & Dress，1999；Zuidema & deBoer，2009 )，但也来自内在信号特征，例如快速衰落 (Roberts & Galantucci, 2012) 或信号域的有限标志性可供性 (Roberts, Lewandwoski & Galantucci, 2015)。当信号不仅接受迭代学习而且还用于传达意义时（Kirby et al., 2015），当意义空间经历扩展（Selten & Warglien，2007），当交流涉及多个对话者时，组合结构就会出现在社交网络中（Raviv、Meyer 和 Lev-Ari，2019 年）或当指涉对象的基于上下文的可预测性较低时（Winters、Kirby 和 Smith，2018 年）。在这些情况下，信号的子成分成为成人和儿童的语言传输 5 系统地与意义维度相关联，类似于自然语言中的形态句法规则（del Giudice，2012；Kirby、Cornish & Smith，2008；Kirby , Tamariz, Cornish & Smith, 2015; Silvey et al., 2014; Verhoef, Roberts & Dingemanse, 2015)。在本研究中，我们询问当儿童学习和使用新信号时，这些基本结果是否以及如何改变。儿童在认知能力、实用能力、预先存在的现实世界知识和先前的语言经验方面与成人不同。因此，重要的是更直接地调查儿童如何创造和传递新的信号系统，以便更好地理解在这个过程中运作的潜在限制以及儿童在语言变化中可能发挥的作用，特别是考虑到语言结构与儿童与成人学习语言的比例以及可能对语言传播过程施加的学习限制的差异有关（Lupyan & Dale，2010；Dale & Lupyan，2012）。关于儿童对交流有效信号系统的出现施加哪些限制以及这些限制与成人施加的限制有何不同的预测应该解决象似性的出现和结构的出现。儿童语言发展研究的结果表明，此类预测不一定是直截了当的：关于象似性的出现，标志性引导假设（Imai & Kita，2014）提出儿童受益于标志性信号-意义映射，因为这种映射是透明的从而更容易理解从而减轻学习负担。因此，儿童应该比成年人更倾向于利用信号特征和意义维度之间透明的跨模式关联。然而，透明跨模式关联的发展起源尚不清楚。最近对婴儿期和幼儿期 kiki-bouba 效应出现的元分析（Ford、Lammertink、Peperkamp、GuevaraRukoz、Fikkert 和 Tsuji，2018 年）表明一些跨模型对应（例如，bouba 效应指的是圆形与后元音和浊辅音的关联）很早就出现了，而其他的（例如 kiki 效应，指尖形与前元音和清辅音的关联）随着时间的推移往往会出现。这将导致相当复杂的预测，根据这些映射，儿童可能更喜欢某些标志性映射，而根据成人和儿童 6 环境中语言传输统计规律的更多经验，成人应该更容易获得其他标志性映射，但目前的文献确实如此不允许我们对特定的年龄相关的跨模式偏好进行预测。对于结构的出现，预测也不一致。一方面，根据 Less-Is-More-h