Research Area

Our laboratory explores how humans acquire language from the very earliest stages of life through adolescence. Language development is a complex process that begins even before a child speaks their first words. We focus on understanding how infants perceive and learn the building blocks of language – such as vowels, consonants, and words – and how these elements come together to form meaningful communication.
To investigate this, we study the brain mechanisms that support language acquisition, examining how young children detect and internalise speech sounds and begin to grasp simple grammatical rules. Our research combines behavioural observations with advanced methods like brain imaging and speech analysis, allowing us to see not only what children learn but also how their brains process language in real time.
In addition to studying perception, we also examine how speech itself develops. By recording and analysing the vocalisations of infants as well as the speech patterns of their caregivers, we can better understand the dynamic “conversation” that shapes language growth. This line of research sheds light on the unique role that early interactions play in helping children become effective communicators.

Another central focus of our lab is the study of social development – the way children learn to understand and interact with the people around them. Social cognitive skills, such as recognising the beliefs, desires, emotions, and the intentions of others, are essential for building trust, forming friendships, and navigating society. These abilities, sometimes called “theory of mind,” begin to emerge in early childhood but continue to develop throughout adolescence.
In our research, we investigate how everyday interactions between infants and caregivers shape the foundations of these social skills. For example, we study how joint attention, turn-taking, emotional expression, and shared activities help infants learn to interpret others’ behaviour and communicate their own needs. By analysing both behaviour and brain activity, we aim to uncover the developmental pathways that allow children to gradually become socially competent individuals.
This research not only deepens our understanding of human development but also provides important insights into the factors that support healthy social growth. In the long term, our findings may contribute to the development of educational approaches and early interventions for children who face challenges in social communication.

In addition to studying language and social growth, our laboratory is deeply interested in how infants and children develop their sensory and perceptual abilities. Human development depends on more than just vision and hearing – touch, smell, and other senses also play a critical role in shaping how children understand and interact with their world.
Our research investigates how these senses emerge and integrate in early life. For example, we examine how infants respond to gentle tactile stimulation, such as stroking, and how such experiences contribute to bonding and emotional regulation. We also explore the role of olfactory cues by studying how mothers react to the scent of their own infants, and how this unique form of recognition influences caregiving behaviours. By looking at these multisensory interactions, we can better understand the deep biological and emotional connections that support early development.
To study these processes, we use a variety of approaches, including behavioural observation, physiological measurement, and brain imaging. Together, these methods allow us to investigate not only what infants perceive, but also how different sensory systems work together to support learning and communication.
Ultimately, our research on perceptual and sensory development highlights the fundamental ways in which children experience the world through their bodies and senses, and how these experiences lay the foundation for later cognitive, emotional, and social growth.

A further focus of our laboratory is the study of motor development – the ways in which infants learn to move and control their bodies. From the first attempts to grasp an object to the milestone of walking independently, motor skills form the foundation of a child’s ability to explore and engage with the world.
Our research examines both fine motor functions, such as reaching and grasping small objects, and gross motor functions, such as crawling and walking. These skills are not only essential for physical independence but are also deeply connected to other aspects of development. For example, the ability to gesture or point supports language acquisition, while coordinated movements during play and interaction help foster social understanding.
To study these links, we combine behavioural observations with measures of brain activity, allowing us to see how the nervous system supports motor development over time. By tracking how infants’ movements change and become more coordinated, we gain insights into the interplay between motor, cognitive, and social growth.
Through this research, we aim to clarify how the seemingly simple acts of moving, reaching, or walking are intertwined with broader developmental processes. Understanding these connections can also provide valuable knowledge for supporting children who face delays or difficulties in motor development.

To better understand how infants and children learn and develop, our laboratory makes use of non-invasive brain measurement techniques. These approaches allow us to see which areas of the brain are active during different tasks, giving us valuable insights into the neural mechanisms that support language, social, sensory, and motor development. Importantly, both methods are safe, gentle and suitable for use even with very young infants.

・Near-Infrared Spectroscopy (NIRS)
NIRS is a technique that uses light to measure brain activity. Infants wear a soft cap fitted with optical sensors, which shine near-infrared light into the head. By tracking how the light is absorbed, we can detect changes in blood flow within the brain. Because blood flow increases in areas that are more active, this method helps us determine which regions of the brain are engaged when a child listens to sounds, looks at pictures, or interacts with caregivers. NIRS is quiet, comfortable, and particularly well-suited for studying babies, making it a powerful tool for developmental research.
・Electroencephalography (EEG)
EEG measures the brain’s electrical activity through sensors placed on the scalp. For this, infants or children wear a lightweight, net-shaped cap containing multiple electrodes. These sensors detect the brain’s naturally occurring electrical signals, which are extremely weak but highly informative. By analysing patterns in these signals, we can understand how the brain responds to sounds, sights, and social interactions in real time. EEG is especially useful for capturing the fast, millisecond-level changes that occur as the brain processes information.

Together, NIRS and EEG provide complementary perspectives: NIRS shows us where brain activity occurs, while EEG shows us when it happens. Using these methods in combination allows our lab to build a richer, more complete picture of how the developing brain supports learning and behaviour.

In addition to measuring brain activity, our laboratory also studies how the body itself responds to changes in thoughts, feelings, and attention. The human body produces a variety of subtle signals—such as changes in heartbeat, skin responses, and eye movements—that can reveal important information about a person’s internal state. By measuring these physiological indicators, we can gain insights into how infants and children experience and react to the world around them.

Some examples of the measures we use include:

• Heartbeat (cardiac activity): By monitoring changes in heart rate, we can track how infants respond to different sounds, sights, or social interactions. A faster or slower heartbeat may reflect attention, excitement, or calming.
• Skin electrical activity (electrodermal response): The skin produces tiny electrical signals that vary with arousal and emotional states. Measuring these signals allows us to assess how strongly an infant reacts to certain stimuli.
• Pupil state (pupillometry): The size and movement of the pupils change in response to light, attention, and mental effort. Tracking these changes provides clues about how infants focus and process information.

These physiological measurements are non-invasive, safe, and suitable for use with even very young infants. By combining them with brain activity data and behavioural observations, we can build a more complete picture of early development—revealing not just what children do, but also how their bodies and minds respond in the moment.

Another important method used in our laboratory is the measurement of eye gaze, which allows us to study where and how children should focus their attention. Eye movements provide a window into the mind, revealing what captures a child’s interest and how they process information in their environment.
We use an eye-gaze measuring device that tracks both eye movements and pupil size by detecting the reflection of a very weak, invisible light emitted from a small camera. The light is completely harmless and so faint that it causes no glare or discomfort. This makes the method safe and reliable for use with infants and young children.
During measurement, children usually sit comfortably on the lap of a parent or guardian while they watch pictures, videos, or other stimuli on a screen. The device then records where their eyes move and how long they look at different areas, providing detailed information about their attention and interest.
Eye-gaze data can reveal, for example, how infants recognise faces, follow movements, or shift their attention in response to social cues. When combined with other methods such as brain activity or physiological measurements, line of sight studies help us better understand the links between perception, cognition, and social development.

Understanding how infants and children move is essential for studying their development. Subtle changes in posture, gestures, and movements often provide clues about motor skills, communication, and social interaction. To capture these details, our laboratory uses a range of motion measurement techniques.
These include motion capture systems, kinetic recording devices, and video-based observation. Motion capture allows us to track body movements with high precision, while kinetic measurements provide information about the forces involved in actions such as reaching or walking. Video recording is also used extensively to document behavior, which can then be carefully analysed through video coding—a method of categorising and quantifying different actions frame by frame.
By applying these methods, we can examine how infants develop fine motor skills like grasping, as well as gross motor abilities such as crawling or walking. Motion measurement is also valuable for studying how children coordinate movements during play, interact with caregivers, or express emotions through body language.
Importantly, these approaches are not limited to infants; we also study older children and adults when the research question calls for comparisons across age groups. By combining motion data with brain and physiological measurements, we gain a comprehensive understanding of how movement reflects and supports cognitive, social, and emotional development.