Speech Perception and Memory in an Episodic Lexicon

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DESCRIPTION (provided by applicant): This research investigates lexical representations in long-term memory and the processes that both encode and retrieve those representations. Most theories assume that speech waveforms are converted to phoneme strings, which are then compared to the mental lexicon. When comparisons yield matches, words are "recognized." This typical view emphasizes the abstract properties of words: Speech signals containing idiosyncratic information (e.g., speaker's voice, ambient noise) are normalized into a canonical form, then matched to abstract lexical entries. Few theories consider idiosyncrasies of speech as more than "noise" in the signal. However, episodic memory models posits that details of perceptual experiences are not forgotten; instead, they are integral to later perception. The proposed research further tests the episodic view, using speech perception, memory, and production experiments, coupled with model simulations. In Project 1, perception and memory experiments will test factors governing episodic content, examining roles of selective attention and working memory. The experiments will assess the nature and extent of perceptual-conceptual tradeoffs in trace formation. In Project 2, multidimensional scaling experiments are coupled with memory tests, with a goal of discovering the similarity-distance function in episodic word priming. Project 3 provides a critical test of the episodic view, using eye-tracking procedures to assess the timecourse of episodic effects in perception. The experiments in Project 4 will examine memory for larger episodic units, using full sentences as stimuli. In addition to standard tests, sentence memory will also be assessed using a novel speech-production method, examining the acoustic-phonetic content of spoken responses. As in previous research, we expect people to spontaneously imitate acoustic patterns of the stimulus sentences. The episodic theory predicts that degrees of imitation will be affected by "abstract" characteristics of the sentences, such as semantic complexity, suggesting that speech acoustics reflect a complex interplay of linguistic stimuli and their episodic representations.