Auditory and cognitive factors in speech perception and category learning

描述（由申请人提供）：来自理想观察者理论的概念将用于研究听觉类别学习和言语感知。理想的观察者提供了一个评估人类在感知任务上的表现的基准，并可以作为开发实际表现模型的适当起点。在第一组实验中，听众将学会对新的非言语刺激进行分类。类别的先验概率和类别重叠的程度将被改变，以评估听者对刺激的分布特性的敏感性。第二组实验将测试语音和非语音感知中的选择性适应和对比效应是否可以建模为听者先验概率和刺激似然分布的变化。第三组实验将扩展我们实验室最近的试点工作，旨在为自然产生的语音开发理想的分类器。这项试点工作的结果表明，听众采用的策略，优化分类性能的自然分布特性的音素在他们的语言。这一假设将在这些实验中得到全面检验。第四组实验将考察观察者如何在做出音素类别判断时对多个证据来源进行加权和整合。我们的目的是了解如何密切听众近似最佳信息权重在这样的任务时，不同的刺激属性是可预测或不可预测的方式退化。在第五组实验中，自然音素分布将被用来估计一组母语（L1）音素对比和第二语言（L2）中的一组竞争对比之间的最佳轨迹。感知数据的L2学习者在不同阶段的熟练程度将进行比较，估计的最佳轨迹。在拟议的研究中开发和测试的技术可以作为重要的工具，在不同程度的听力损失，包括那些与人工耳蜗植入的听众的语音感知的研究。特别是，推导出的理想分类器的听觉输入被限制模仿特定的听力受损的个人，可以让调查人员区分性能的限制，由于感官因素和那些可归因于非最佳的分类策略。

DESCRIPTION (provided by applicant): Concepts from ideal observer theory will be used to study auditory category learning and speech perception. Ideal observers provide a benchmark for assessing human performance on perceptual tasks and may serve as an appropriate starting point for developing models of actual performance. In the first set of experiments, listeners will learn to categorize novel non-speech stimuli. Prior probabilities of the categories and degree of category overlap will be varied to assess listeners' sensitivity to the distributional properties of the stimuli. The second set of experiments will test whether selective adaptation and contrast effects in speech and non- speech perception can be modeled as changes in the listeners' prior probability and stimulus likelihood distributions. The third set of experiments will extend recent pilot work in our laboratory aimed at developing ideal classifiers for naturally produced speech sounds. The results of this pilot work suggest that listeners adopt a strategy of optimizing categorization performance with respect to the natural distributional properties of phonemes in their language. This hypothesis will be comprehensively tested in these experiments. The fourth set of experiments will examine how observers weight and integrate multiple sources of evidence in making phoneme category judgments. The aim is to learn how closely listeners approximate optimal informational weightings in such tasks when different stimulus properties are degraded in either predictable or unpredictable ways. In the fifth set of experiments, natural phoneme distributions will be used to estimate optimal trajectories between a set of native language (L1) phoneme contrasts and a competing set of contrasts in a second language (L2). Perception data of L2 learners at varying stages of proficiency will be compared to the estimated optimal trajectories. The techniques developed and tested in the proposed studies can serve as important tools for the study of speech perception in listeners with varying degrees of hearing loss, including those with cochlear implants. In particular, the derivation of ideal classifiers whose auditory input is restricted to mimic that of particular hearing-impaired individuals may allow investigators to distinguish between limits on performance due to sensory factors and those attributable to non-optimal categorization strategies.