Why do non-native English speakers show masked form priming when native speakers do not?

Native English speakers do not show masked priming effects in lexical decision when a prime word is related to its target purely on the basis of orthographic form (e.g., pillow-PILL, protest-PROTECT). There is strong evidence, however, that non-native English speakers do show such form priming. This paper explores the possible cognitive mechanisms behind this difference between native and non-native speakers. Taft and Li (2020) found that only non-native speakers (with Chinese as their first language) showed priming when the nonword prime ended in the same embedded word as the word target (e.g., plerough-THOROUGH), but a newly reported experiment goes on to show priming for native speakers as well when the shared letter-combination is not itself a word (e.g., celtoise-TORTOISE). This contrast in results leads to the interpretation that native speakers have a specific mechanism for activating embedded words that is important when recognizing polymorphemic words through their stems. It is suggested that non-native speakers, or at least those with Chinese as their first language, do not engage or are slow in engaging such a mechanism. The form priming that they demonstrate arises from facilitated processing of the repeated letters rather than the pre-activation of a lexical representation.