Scientists have a non-invasive tool that offers a window into a young child’s mind by observing their gaze. Eye tracking provides insights into behavioral and cognitive processes long before a child can talk. This technology allows researchers to understand a toddler’s development by precisely monitoring what they look at and for how long.
Understanding Eye Tracking Technology with Toddlers
Eye tracking works by using a safe, invisible near-infrared light that is projected onto the eye. A camera then tracks the reflection of this light off the cornea to pinpoint the exact location of the toddler’s gaze on a screen. This method is known as Pupil Center Corneal Reflection (PCCR). The system calculates the relationship between the pupil and the corneal reflection to produce an estimate of where the person is looking.
The setup for toddlers is non-intrusive and engaging. Researchers use remote, screen-based trackers that are mounted below a computer monitor, which allows the child to sit comfortably on a parent’s lap without any head-mounted gear. To keep the child’s attention, the stimuli presented on the screen are in the form of cartoons or simple games. This naturalistic approach allows researchers to study behavior in a more familiar and comfortable environment for the child.
Several metrics are measured during these sessions. These include gaze duration, which is how long a child looks at a specific object, and scan paths, which trace the sequence of eye movements between different points of interest. Pupil dilation, the widening of the pupil, is also monitored as it can indicate cognitive effort or emotional response.
Revealing Cognitive and Social Development
By analyzing where children direct their attention, researchers can gain insights into the foundational aspects of cognition and social understanding. These studies help to map out developmental milestones that occur long before a child can articulate their thoughts and intentions.
The technology is particularly useful in studying language acquisition. For example, a toddler might look at a speaker’s mouth as they talk and then shift their gaze to the object being named, demonstrating the process of connecting words with their meanings. This provides information about how children develop word recognition and comprehension.
Eye tracking also helps researchers understand the emergence of social skills. Through these experiments, it has been shown that toddlers prefer to look at human faces and biological motion over other objects. This preference for social stimuli is a building block for skills like joint attention, where a child follows an adult’s gaze to an object, showing a shared focus. The way a child explores faces, particularly the eye area, plays a role in the development of social communication.
The technology can reveal a toddler’s problem-solving abilities. When presented with a scenario, such as a ball rolling behind a barrier, a toddler’s eye movements can show that they are visually scanning the scene to anticipate where the ball will reappear. This anticipatory looking demonstrates an early understanding of object permanence and the ability to predict future events based on visual information.
Identifying Early Signs of Developmental Conditions
Eye tracking is also being used to identify early differences in visual attention that may be associated with certain developmental conditions. While not a standalone diagnostic tool, it can be a component of early screening, helping to detect variations in gaze patterns that might suggest a child is developing differently. This allows for earlier intervention and support.
Research has focused on Autism Spectrum Disorder (ASD), where differences in gaze patterns have been observed in infants as young as 14 months. In some studies, toddlers who were later diagnosed with autism tended to look more at movies of geometric shapes, while typically developing toddlers preferred to watch videos of children dancing. If a toddler spent more than 70% of their time looking at geometric patterns, the likelihood of accurately classifying them as having an ASD was very high in one study.
These findings suggest that a preference for non-social stimuli from a young age could be an early indicator of ASD. Other observed differences include reduced focus on people’s eyes in social scenes and a tendency to look at mouths instead. These distinct visual patterns can help researchers better understand the nature of these conditions and provide objective data to support other developmental assessments.
The Process of an Eye Tracking Assessment
The process for an eye tracking assessment is designed to be simple and stress-free. The session takes place in a quiet room at a university lab or a clinic. The environment is kept calm to ensure the toddler is comfortable and can focus on the screen without distractions.
During the assessment, the toddler sits in front of a monitor equipped with an eye tracker. The child is not required to wear any special equipment, and the eye tracker itself is a discreet device located near the screen. The parent is present to provide comfort and support, helping the child feel secure throughout the process.
The assessment itself is brief, often lasting only five to ten minutes. The toddler is shown a series of short, engaging videos or images, such as cartoons or colorful patterns. The child does not need to make any active response; they simply watch the screen as they normally would. The technology passively records their eye movements as they view the stimuli.