Will Lexical Contextual Diversity Replace Word Frequency? Evidence From Behavior And Neuroelectrophysiology

Word frequency is one of the most important research variables in word recognition and even in lexical cognition for a long time.In many existing models of visual word recognition,word frequency occupies a very large explanatory power.However,as the research progressed,it was found that the variable of word frequency did not explain all the changes caused by the word frequency.Therefore,Adelman(2006)proposed the concept of contextual diversity.Contextual diversity is the number of contexts in which a word appears.Brysbaert(2009)then operationalized the concept of contextual diversity,where contextual diversity refers to the number of movies or TV shows a word appears in the subtitle corpus.The study found that it was word contextual diversity affects word lexical decision time rather than word frequency,specifically,word frequency effect disappears under the condition of controlling contextual diversity;while when word frequency controlled,the effect of word contextual diversity still exists.However,with the deepening of researches on word contextual diversity,it was found that the effects of word frequency and contextual diversity have been separated in word learning.There is a growing body of evidence that research on word frequency and contextual diversity remains controversial,and behavioral approaches of reaction time can not solve these controversies.Therefore,the time-sensitive ERPs technology become priority to solve this controversy.Since Chinese can be less affected by the orthographic effect,it becomes a better material for studying word contextual diversity and word frequency.Therefore,in the present study,we use Chinese as materials to study whether word contextual diversity exists in Chinese based on lexical decision task,and the electrophysiological mechanism of word contextual diversity.In the first study,38 college students were asked to use the lexical decision task to explore whether word contextual diversity exists in Chinese.It is required that participants make judgments on 40 high-frequency low-contexttual words,40 low-frequency and low-contextual words,40 high-frequency and high-contextual words and correspondingly created pseudowords,and then record the correct rate and reaction time of participants.In Experiment 2,ERPs were used to record the EEG data of the participants in the same experimental materials.Time-frequency analysis was also used to reveal the time course and neural mechanism of word contextual diversity,and then to answer the cognitive driving mechanism with diverse word frequency and contextual diversity.Experiment 1 finds that there is also the same effect of word contextual diversity in Chinese.There is no significant difference in word frequency and word contextual diversity in correctness.In reaction time,when controlling word contextual diversity,word frequency effect disappears,the effect of word contextual diversity still exists when word frequency is controlled,thus verifying word contextual diversity effect exists.Experiment 2 finds:(1)The behavioral results are the same as experiment 1.(2)In the ERP results,there is a separation between word frequency effect and word contextual diversity effect.Specifically,the N400 component is induced by the word frequency effect,which is the largest in the left front central area of head;the word contextual diversity induces the late positive component(LPC),which is the largest in the central head.(3)Time-frequency analysis shows that the word frequency effect has a suppressed alpha-band power,and word contextual diversity has an increase in delta and beta-band power.Thus the electrophysiological results finds that word frequency effect and word contextual diversity have separate influences on word recognition.In summary,using Mandarin as materials,we find that there is also the same effect of contextual diversity in Chinese.Our research using E RPs found a separation of the two effects.Given the limitations of the reaction time approach,we have reason to believe that word frequency and word contextual diversity are two different variables that affect word recognition.