Can personality affect grammatical processing? Tolerance of ambiguity and relative clause attachment in multilingual speakers

While grammatical processing has been extensively examined across languages, relatively few studies have linked it to psychological variables such as personality. We propose that one relevant trait, Tolerance of Ambiguity (TA), reflecting comfort with uncertainty and multiple interpretations, may predict how structural ambiguity is resolved during grammatical processing. We investigate the interpretation of ambiguous relative clauses in L2 English (e.g. I saw the servant[NP1] of the actress[NP2] who lives in the neighbourhood) among 126 young adult native speakers of Polish (L1) learning L2 English only (bilinguals; n = 63) or L2 English and L3 German (trilinguals; n = 63). In these sentences, English speakers typically favour the NP2 interpretation, whereas German speakers prefer NP1. The results show that TA, measured with the 12-item short form of the Tolerance of Ambiguity Scale (Herman et al. 2010), interacts with L3 German knowledge: its effect is significant only in trilinguals. At higher TA levels, trilinguals display greater variability than bilinguals, fluctuating more often between NP1 and NP2 interpretations. Moreover, trilinguals select NP1, the interpretation preferred in German, significantly more frequently. We propose two possible explanations: (1) a direct influence of L3 German, modulated by TA, and (2) an indirect effect of multilingualism.