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Over the past 35 years, it has been established that mental representations of language include fine-grained acoustic details stored in episodic memory. The empirical foundations of this fact were established through a series of word recognition experiments showing that participants were better at remembering words repeated by the same talker than words repeated by a different talker (talker-specificity effect). This effect has been widely replicated, but exclusively with isolated, generally monosyllabic, words as the object of study. Whether fine-grained acoustic detail plays a role in the encoding and retrieval of larger structures, such as spoken sentences, has important implications for theories of language understanding in natural communicative contexts. In this study, we extended traditional recognition memory methods to use full spoken sentences rather than individual words as stimuli. Additionally, we manipulated attention at the time of encoding in order to probe the automaticity of fine-grained acoustic encoding. Participants were more accurate for sentences repeated by the same talker than by a different talker. They were also faster and more accurate in the Full Attention than in the Divided Attention condition. The specificity effect was more pronounced for the Divided Attention than the Full Attention group. These findings provide evidence for specificity at the sentence level. They also highlight the implicit, automatic encoding of fine-grained acoustic detail and point to a central role for cognitive resource allocation in shaping memory-based language representations. 

It is now well established that memory representations of words are acoustically rich. Alongside this development, a related line of work has shown that the robustness of memory encoding varies widely depending on who is speaking. In this dissertation, I explore the cognitive basis of memory asymmetries at a larger linguistic level (spoken sentences), using the mechanism of socially guided attention allocation to explain how listeners dynamically shift cognitive resources based on the social characteristics of speech. This dissertation consists of three empirical studies designed to investigate the factors that pattern asymmetric memory for spoken language. In the first study, I explored specificity effects at the level of the sentence. While previous research on specificity has centralized the lexical item as the unit of study, I showed that talker-specific memory patterns are also robust at a larger linguistic level, making it likely that acoustic detail is fundamental to human speech perception more broadly. In the second study, I introduced a set of diverse talkers and showed that memory patterns vary widely within this group, and that the memorability of individual talkers is somewhat consistent across listeners. In the third study, I showed that memory behaviors do not depend merely on the speech characteristics of the talker or on the content of the sentence, but on the unique relationship between these two. Memory dramatically improved when semantic content of sentences was congruent with widely held social associations with talkers based on their speech, and this effect was particularly pronounced when listeners had a high cognitive load during encoding. These data collectively provide evidence that listeners allocate attentional resources on an ad hoc, socially guided basis. Listeners subconsciously draw on fine-grained phonetic information and social associations to dynamically adapt low-level cognitive processes while understanding spoken language and encoding it to memory. This approach positions variation in speech not as an obstacle to perception, but as an information source that humans readily recruit to aid in the seamless understanding of spoken language.