When learning a second language (L2), many are likely familiar with the challenge of memorizing vocabulary, only to struggle with recalling and using it fluently in speech. Studies have found that speaking fluently in L2 depends not only on knowing what words mean but also on how quickly and automatically you can access and use them appropriately in contexts. This ability to retrieve contextually appropriate word meanings without conscious effort is known as automatized vocabulary knowledge (AVK).
In a new study, a team of researchers led by Mr. Kotaro Takizawa from Waseda University, Japan, along with Prof. Kazuya Saito and Dr. Yui Suzukida from University College London and Tohoku University, Mr. Satsuki Kurokawa and Dr. Takumi Uchihara from Tohoku University, Japan, compared AVK with declarative vocabulary knowledge (DVK) to explore the extent to which AVK predicts L2 utterance fluency. Their findings were published in the journal of Applied Linguistics on July 7, 2025.
"Our study addressed an outstanding question regarding the vocabulary knowledge that best supports automaticity in L2 speech production," says Takizawa.
To investigate the relationship between each type of vocabulary knowledge and speaking fluency, the researchers assessed the AVK and DVK of 210 university students who were learning English as L2.
To evaluate DVK, participants were asked to match spoken English words with their Japanese meanings with options, capturing decontextualized word knowledge stored in memory. In contrast, AVK was evaluated by having participants listen to short English sentences and determine whether they were meaningful, testing their ability to process contextualized word meanings in real time. Next, participants took part in two speaking exercises: a narrative task based on a picture sequence and a personal monologue in response to an on-screen prompt. Further, the researchers measured fluency by analyzing three key indicators: articulation rate, which reflects how quickly a person speaks; mid-clause silent pauses, or pauses that occur within a clause; and end-clause silent pauses, which occur at the end of a clause.
Across all measures, AVK was a significantly stronger predictor of L2 speaking fluency than DVK, which showed little to no effect. Notably, mid-clause silent pauses—which indicate difficulty in linguistic encoding, such as retrieving words while speaking—were more strongly linked to AVK, suggesting that the ability to automatically access vocabulary in context plays a crucial role in fluent speech.
This finding has important implications for language learning, highlighting that fluency does not come simply from knowing more words but from sophisticating them so that they can be retrieved quickly and confidently—skills that can be developed through continuing practice and exposure to language in context. The findings suggest that learners first familiarize themselves with simple word forms and their meanings and then gradually transition to how words are used in real-world, sentence-level contexts.
"Our findings strongly support the view that building simple form-meaning connections is only the first step in L2 vocabulary learning. To become orally fluent, learners need to automatize these connections through consistent practice and meaningful exposure," concludes Takizawa.
