The Effects Of Lexical Densities And Task Types On Senior High School Students’ Incidental Vocabulary Acquisition

Reading provides learners with contextual support to acquire words incidentally and enables them to acquire the words compatible with their knowledge framework.This process is affected by multiple factors: In regard to textual variables,studies exploring the relation between lexical density and the rate of acquisition mostly target second language learners.As for senior high school students who learn English in the foreign language learning context,more studies urgently need to identify the lexical density suitable for reading.When it comes to task types,a range of studies have proved that output tasks are more effective on vocabulary acquisition than input ones,but the tasks involved are largely semi-controlled ones(i.e.,gap-filling,sentence-making),which lack diversity.Therefore,this study,designed as a2x2 matrix,on the theoretical basis of knowledge visualization theory,interactive alignment as well as involvement load hypothesis,attempts to investigate the effects brought by different lexical densities(2%,5%)and task types(mind map,continuation task)on eleventh grade students.The research questions to be answered are as follows:1.What effects do different lexical densities have on eleventh grade students’ incidental vocabulary acquisition?2.What effects do different task types have on eleventh grade students’ incidental vocabulary acquisition?3.What effects do the combinations of lexical densities and task types have on eleventh grade students’ incidental vocabulary acquisition?The participants involved were eleventh grade students from 4 classes at a senior high school in Guizhou province.Before the experiment,all the students had taken the English academic test.According to their scores in the reading section,126 participants were finally selected.Then,these subjects accordingly corresponded to 4 groups,where the treatment condition for each group consisted of two variables(G1: 2%+mind map,G2: 5%+mind map),G3: 5%+continuation task,G4: 2%+continuation task).This study spreads three weeks.To ensure the suitability of target word selection as well as time allotment,a pilot study was administered to another class in the first week.For the second week,each group would receive an instruction once they finished reading.Then,they had to complete the corresponding post-reading task and immediate posttest.The delayed posttest was conducted in the third week.In order to learn about the students’ opinions toward the post-reading tasks,8 students were selected to have a brief interview.By analyzing the data with SPSS.26,some findings could be summarized as follows:1.lexical density(2%,5%)would not result in a significant difference on eleventh grade students’ incidental vocabulary acquisition.2.Task types(mind map,continuation task)would bring about a significant difference on eleventh grade students’ quality of acquisition.Though the two tasks contributed to the students’ incidental vocabulary acquisition,the effect of mind map was superior to that of continuation task.3.Under different factors-combination of lexical densities and task types,there were differences on eleventh grade students’ incidental vocabulary acquisition.Based on pairwise comparisons,it was discovered that the comparative advantage of mind map only occurred under the relatively high percent of lexical density(5%).Whether it was receptive vocabulary,productive vocabulary,or word retention,the scores of group 2(5%+mind map)were significantly higher than group 3(5%+continuation task).Additionally,in terms of productive vocabulary,another statistical difference was found between group 4(2%+continuation task)and group 3(5%+continuation task),and the group with 2% of lexical density achieved higher scores.Namely,when the post-reading task was continuation task,the text of 2% of lexical density more facilitated output vocabulary.The results above had some implications on vocabulary teaching:Firstly,2% to 5% of lexical density was a proper range for eleventh grade students to acquire words incidentally.Secondly,when it comes to task types,continuation task was more suitable for the textual material with less new words;the range of texts that mind map could be compatible with was wider than continuation task.It was suggested to adopt mind map more often in post-reading procedure,so that the learners could acquire words incidentally and use words correctly while establishing their own textual framework.