The Role of Speech Perception Gradiency in L1 versus L2 Spoken Word Recognition

Speech perception gradiency reflects sensitivity to subphonemic differences. Prior research has shown that gradiency facilitates recovery from misperceptions (i.e., speech perception flexibility) in L1 (Kapnoula et al., 2021), but whether and how gradiency contributes to speech perception flexibility in L2 remains unknown. This study investigated the role of gradiency in spoken word recognition among Spanish (L1)-English (L2) bilinguals. Gradiency was assessed using a Visual Analogue Scale (VAS) with stop consonants (/b/-/p/), and initial activation of a lexical competitor and speech perception flexibility were assessed using an eye-tracking Visual World Paradigm (VWP) task. Seventy Spanish-English bilinguals completed these tasks in both languages. Following previous results in L1 English, gradiency facilitated speech perception flexibility in L1 Spanish. In contrast, gradiency did not facilitate L2 speech perception; instead, a different pattern emerged: participants relied more heavily on lexical (top-down) than subphonemic (bottom-up) information, as would be expected given the less robust category representations in L2. Additionally, a positive correlation between L1 and L2 gradiency was observed only among higher-proficiency listeners. Overall, these findings suggest that the functional role of gradiency in L1 versus L2 speech perception is modulated by the differential reliance on bottom-up versus top-down information.