Language-Specific or Universal? The Nature and Roles of Consistency and Gradiency in Speech Perception

Speech perception gradiency allows listeners to detect and maintain subphonemic information, thereby enhancing speech perception flexibility. However, its nature is not fully understood; it is unclear whether gradiency is a generic trait, or if it depends on language status (L1 vs. L2) and/or language-specific properties (e.g., voice onset time). To address these questions, we investigated the functions of gradiency in spoken word recognition by Spanish (L1)-English (L2) bilinguals. In addition, we examined the role of perceptual consistency, a measure reflecting the stability of auditory cue encoding. Gradiency and perceptual consistency were assessed using the Visual Analogue Scale (VAS). Spoken word recognition was evaluated through initial lexical activation and speech perception flexibility, quantified by the likelihood and speed of recovery from misleading information, using an eye-tracking Visual World Paradigm (VWP) task. Seventy Spanish-English bilinguals performed these tasks in both Spanish and English. Results revealed that listeners with higher gradiency recovered faster from misleading information in L1 Spanish and those with higher perceptual consistency relied more on early information to activate lexical candidates in both languages. This study highlights the language-specific benefit of gradiency in speech perception flexibility and provides general evidence that speech processing stability facilitates initial lexical activation.