Data_Sheet_1_The Emergence of Discrete Perceptual-Motor Units in a Production Model That Assumes Holistic Phonological Representations.pdf

Intelligible speakers achieve specific vocal tract constrictions in rapid sequence. These constrictions are associated in theory with speech motor goals. Adult-focused models of speech production assume that discrete phonological representations, sequenced into word-length plans for output, define these goals. This assumption introduces a serial order problem for speech. It is also at odds with children's speech. In particular, child phonology and timing control suggest holistic speech plans, and so the hypothesis of whole word production. This hypothesis solves the serial order problem by avoiding it. When the same solution is applied to adult speech the problem becomes how to explain the development of highly intelligible speech. This is the problem addressed here. A modeling approach is used to demonstrate how perceptual-motor units of production emerge over developmental time with the perceptual-motor integration of holistic speech plans that are also phonological representations; the specific argument is that perceptual-motor units are a product of trajectories (nearly) crossing in motor space. The model, which focuses on the integration process, defines the perceptual-motor map as a set of linked pairs of experienced perceptual and motor trajectories. The trajectories are time-based excursions through speaker-defined perceptual and motor spaces. By hypothesis, junctures appear where motor trajectories near or overlap one another in motor space when the shared (or extremely similar) articulatory configurations in these regions are exploited to combine perceptually-linked motor paths along different trajectories. Junctures form in clusters in motor space. These clusters, along with their corresponding (linked) perceptual points, represent perceptual-motor units of production, albeit at the level of speech motor control only. The units serve as pivots in motor space during speaking; they are points of transition from one motor trajectory to another along perceptually-linked paths that are selected to produce best approximations of whole word targets.

具备言语可理解性的说话者能够以快速连续的序列完成特定的声道（vocal tract）收缩动作。理论上，这些收缩动作与言语运动目标（speech motor goals）相关联。面向成人的言语产生模型假设，离散的语音表征（phonological representations）被编排为用于输出的词长计划（word-length plans），以此界定上述言语运动目标。这一假设为言语加工带来了序列顺序问题（serial order problem），同时也与儿童言语的实际表现相悖。具体而言，儿童的语音学系统与时序控制机制均指向整体言语计划（holistic speech plans），由此催生了整词产生（whole word production）这一假说。该假说通过规避序列顺序问题来解决这一难题。若将该解决方案推广至成人言语研究，则需解决如何解释具备高度可理解性的成人言语的发育机制这一新问题。本文正是针对这一问题展开研究。本研究采用建模方法，旨在阐明知觉运动单元（perceptual-motor units）如何在发育过程中，通过对同时兼具语音表征属性的整体言语计划进行知觉运动整合（perceptual-motor integration）而形成；本文的核心论点为：知觉运动单元是运动空间（motor space）中（近似）相交的运动轨迹的产物。本模型聚焦于知觉运动整合过程，将知觉运动映射（perceptual-motor map）定义为一系列经关联的、由经验习得的知觉轨迹与运动轨迹组成的配对集合。这些轨迹是基于时间的动态偏移过程，穿行于说话者自身界定的知觉空间与运动空间之中。根据假说，当运动空间中特定区域的共享（或高度相似的）发音构型（articulatory configurations）被用于沿不同轨迹结合知觉关联的运动路径时，运动轨迹之间便会在该空间内彼此趋近或重叠，由此形成接合点（junctures）。接合点会在运动空间中聚集成簇。这些成簇的接合点及其对应的（关联的）知觉点位，共同构成了知觉运动单元——尽管其仅局限于言语运动控制层面。在言语产生过程中，这些单元充当运动空间内的转换枢纽；它们是沿知觉关联路径从一条运动轨迹切换至另一条轨迹的节点，而这些路径均经筛选，以最大程度逼近整词产生的目标。