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日本語

In an increasingly globalized world, we often hear about the importance of improving English proficiency. However, we Japanese are said to be very weak in the pronunciation of and the hearing and distinguishing of L and R which are sounds that do not originally exist in Japanese, such as in "glass" and "grass". Given our understanding that words that cannot be recognized cannot be pronounced, the ability of each person to hear and distinguish English is a very important indicator in effective English learning.

As in the proverb: "The eyes say more than the mouth", it is known that pupil dilation can reveal various cognitive states. So, the research team tried to estimate the ability to hear and distinguish L and R by focusing on pupillary dilation response in which the pupil dilates with respect to the difference in sound. For this study, the research team played a repeating loop of words with an English L sound (e.g., "light") into which were randomly dispersed examples of the same word but with an R sound (e.g., "right"). The team then investigated how the pupils of test participants responded to those sounds. Participants were classified into two groups according to their scores in a test of their ability to distinguish English sounds, which was performed in advance, to compare the pupillary response of both groups.

As a result, the group with a strong ability to hear and distinguish the L and R sounds showed a larger pupillary response than the group with a weak ability to hear and distinguish them. It was also found that this pupillary response alone could estimate the ability of the participants who had been tested in advance to hear and distinguish English, with extremely high accuracy. Participants of the experiment were not required to pay attention to the English words they were listening to, they just needed to let them play, but their ability to hear and distinguish could be estimated from their pupillary responses alone at that time. The researchers believe that in future, this finding could provide a new indicator for a simple estimate of the ability of a person to hear and distinguish English.

"Up to now, the evaluation of an individual’s English listening ability has been carried out by actually performing a test in which they are made to listen to English words, and scoring whether the answers are correct or incorrect. However, we focused on the pupil, which is a biological signal, with the goal of extracting objective abilities that did not depend on the participants’ responses. Although all research participants could identify that there were two different sounds being played, their pupillary responses differed according to their English ability. So, I believe that this indicates that there is a possibility that our pupillary responses are reflecting differences in unconscious language processing", the lead author Yuya Kinzuka, a PhD candidate, explained.

Professor Shigeki Nakauchi, who is the leader of the research team, explained, "It was difficult for even the person themselves to recognize their listening ability, which sometimes led to a decrease in training motivation. However, this research has made it possible for not only the person themselves, but also a third party to visualize the listening ability of the learner objectively from the outside. I expect that in the future, objective measurement of the ability to hear and distinguish things will progress in various fields such as language and music."

In addition, explains research member Professor Tetsuto Minami, "This discovery shows that not only simple sounds such as pure tones, but also higher-order factors such as differences in utterances are reflected in pupillary response. I expect that it will be useful as an English learning method if it is possible to improve the ability to hear and distinguish things by controlling pupil dilation from the outside."

The research team has suggested that a new method to estimate the ability to distinguish English sounds from pupillary response, based on these research results, could form the basis of a system for efficiently studying the ability of Japanese people to distinguish the challenging L and R sounds. Furthermore, it is known that learning difficulties caused by the distinguishing of sounds that do not exist in the native language also occur when for example an English speaker learns Chinese. Ultimately then, we hope that this will become a new indicator of estimating language ability that is not limited to Japanese. In addition, these research results are expected to be useful for language learning in patients with movement and speech disorders as there is no need for the participants to pay attention to or physically respond to English words.

This study was conducted with the assistance of Grants-in-Aid for Scientific Research A(26240043) and Basic Research B(17H01807) from the Japan Society for the Promotion of Science, Ministry of education.