| Inhibitory control,as one of the core executive functions,is “the ability to ignore irrelevant information and attend to relevant information”(Schroeder & Marian 2017: 9).There is a distinction between two types of inhibitory control,namely,response inhibition and interference suppression(Bunge et al.2002).Many studies have proved that inhibitory control is an experience-dependent cognitive ability that can be influenced by foreign language learning experience and supported bilingual advantages in inhibitory control over monolinguals(e.g.Bialystok et al.2005;De Cat et al.2018;Martin-Rhee & Bialystok 2008).Against the backdrop of increasingly frequent cross-cultural communication,trilinguals constitute a large population in the world and trilingualism becomes a norm in some countries and areas.In China’s higher education,English majors are required to learn a third language and thus they form a stable trilingual group in China.Recently,research on the cognitive effects of learning foreign languages has been extended to the domain of trilingualism.Studies on the cognitive profile of trilinguals is indispensable for understanding cognitive plasticity and establishing a comprehensive cognitive theoretical framework.However,there has not been conclusive evidence for trilingual advantage in inhibitory control.The present study aims to investigate the effects of third language learning in an instructional context on the development of two types of inhibitory control,namely,response inhibition and interference suppression,taking the modulation effect of third language proficiency,cross-linguistic similarity,and task type into account.More specifically,this study attempts to answer the following research questions:(1)Do third language learners outperform second language learners in two types of inhibitory control?(2)Do third language learners with higher L3 proficiency outperform third language learners with intermediate and lower L3 proficiency in two types of inhibitory control?(3)Do third language learners learning an L3 that shares more cross-linguistic similarity with their L2 outperform third language learners learning an L3 that has less cross-linguistic similarity with their L2 in two types of inhibitory control?The present study involved 157 undergraduates at a key university in China,among whom were 36 second language learners and 121 third language learners.All participants’ native language is Chinese and their second language is English.All second language learners were labeled Group L2.According to third language learning time,third language learners were divided into three subgroups with different L3 proficiency,namely,Group A(lower L3proficiency),Group B(intermediate L3 proficiency),and Group C(higher L3 proficiency).According to the cross-linguistic similarity between L3 and L2,Group A was subdivided into Group A-French(highest similarity),Group A-German(intermediate similarity),Group A-Russian(lower similarity),and Group A-Japanese(lowest similarity).In the same way,Group B was further divided into Group B-French(highest similarity),Group B-Russian(lower similarity),and Group B-Japanese(lowest similarity).Group C were divided into Group C-French(highest similarity),Group C-German(intermediate similarity),and Group C-Japanese(lowest similarity).Simon Arrow Task was used to test inhibitory control.The task consisted of less demanding univalent task measuring response inhibition and more demanding bivalent task measuring interference suppression.When measuring response inhibition in univalent task,arrow stimuli were presented in the center of the screen.Univalent task was composed of a CONTROL condition,in which participants were required to indicate the direction of arrows,and a REVERSE condition,in which participants were required to indicate the opposite direction of arrows.When measuring interference suppression in bivalent task,arrow stimuli were presented on the left or right side of the screen.Bivalent task was composed of stimulus-position congruent trials and stimulus-position incongruent trials.Participants were required to neglect the location of arrow stimuli and indicate the direction of arrows.In order to measure different levels of interference suppression,bivalent trials were further divided into a less demanding blocked SINGLE condition(congruent and incongruent trials were separately presented)and a more demanding MIXED condition(congruent and incongruent trials were randomly mixed).Both accuracy rate and reaction time of each trial of these tasks were recorded and analyzed to compare the differences in response inhibition and interference suppression between L2 learners and L3 learners.Additionally,a Language Background Questionnaire was used to gather participants’ basic information such as language learning history,the frequency and occasion of L2 and L3 use and to match the participants and control the intervening factors.Each of the two independent variables(accuracy rate and reaction time)was separately analyzed with the use of mixed ANOVA.The results of mixed ANOVA showed that:(1)L3 learners did not outperform L2 learners in response inhibition since there were no significant differences between two language groups in either accuracy or reaction time.However,L3 learners outperformed L2 learners in interference suppression.Group A did not perform significantly differently from Group L2 in interference suppression.But Group B and Group C were significantly better than Group L2 in interference suppression.This third language learners’ advantage in interference suppression was indicated by a significant interaction effect between language group(Group L2 vs.Group B;Group L2 vs.Group C),trial condition(SINGLE condition vs.MIXED condition),and congruence(congruent trials vs.incongruent trials)for reaction time.Trilingual advantage in interference suppression but not response inhibition could be attributed to the assumption that response inhibition and interference suppression follow two different trajectories(Bunge et al.2002).Interference suppression is a higher level of inhibitory system that is required when L3 learners inhibit the interference from the representational system of non-target languages,so it is gradually improved as a consequence of L3 learning.(2)L3 learners with higher L3 proficiency did not outperform those with intermediate or lower L3 proficiency in either response inhibition or interference suppression,since there were no significant differences between three language groups in either accuracy or reaction time.This might be due to the small sample size of L3 learners and a low variability in L3 proficiency within the participant sample.(3)L3 learners learning an L3 that shares more cross-linguistic similarity with their L2 outperformed third language learners learning an L3 that shares less cross-linguistic similarity with their L2 in response inhibition,as was indicated by a significant interaction effect between language group(Group C-French,Group C-Japanese vs.Group C-German)and trial condition(CONTROL condition vs.REVERSE condition)for reaction time.However,L3 learners learning an L3 that shares more cross-linguistic similarity with their L2 did not outperform third language learners learning an L3 that shares less cross-linguistic similarity with their L2 in interference suppression since there were not significant differences among L3 learners of different L3 s.The effects of cross-linguistic similarity could be interpreted by the assumption that more interference could be incurred by more cross-linguistic similarity between L2 and L3,the process of which demands more involvement of inhibitory control resources and then progressively improves inhibitory control.This study has not only enriched research on inhibitory control in the domain of third language acquisition but also provided evidence for the effects of foreign language learning on cognitive development and the modulation effect of task demand,language proficiency,and between-language similarity.On the basis of the research findings,the present study concluded that theoretically,L3 learning can improve language learners’ higher-level inhibitory control(interference suppression),but not lower-level of inhibitory control(response inhibition),which supported the Adaptive Control Hypothesis(Green & Abutalebi2013).Cross-linguistic similarity has the modulation effect on response inhibition.Methodologically,the author proposed when observing trilingual advantage in inhibitory control over bilinguals,interference suppression is a better indicator.Compared to accuracy,reaction time is a better indicator.Pedagogically,L3 teaching courses are suggested during foreign language teaching planning for non-English majors. |
