During the first two years of life, infants actively interact with their environment, quickly learning new skills through observation and reasoning. To test how well babies remember objects, a study was conducted at Boston University.
The test the researchers developed is a child-friendly version of a popular card game that involves showing face-up cards on a computer screen and then turning them over. As in the original game, the goal was to find matching cards. The infants participating in the experiment were too young to point out the correct cards or even understand the instructions on their own. Therefore, in order to verify that the infant was looking in the direction of the matching card, a device using infant eye tracking technology was used. Infants were rewarded for matching cards with fun, visual rewards. In this way, they were encouraged to look. However, the extent to which these infants made an effort is unknown.
Motivation and effort are relatively easy to determine in adults and older children. Simply saying, “Please try your best on this test – think carefully about your answers – and if you do well, you will get a reward!” is enough. With a one-year-old child, such a request is not enough. Children’s skills will not be appreciated at all if researchers do not isolate the moments when infants perform the task and instead average them together with moments of inattention. The study decided to use measurement of infants’ pupil dilation to examine working memory overload and emotional response during task performance.
The pupillary response to light is a well-known reflex in which the pupil of the eye (or more specifically, the pupil sphincter muscle) constricts in a bright environment and dilates in the dark so that more light can reach the eye. There is also another pupillary response related to the brain’s arousal system through working memory load.
Pupillometry or the field that deals with measuring the width of the pupil in response to psychophysiological stimuli. For the past 50 years, the momentum of research related to pupillometry has steadily increased. Nobel laureate Daniel Kahneman popularized this field of oculography, primarily to gain insight into cognitive function.
In a study, performing cognitive tasks by children made it possible to observe changes in their pupil. The greater the mental effort, the larger was their pupil diameter. That is, the increase in their brain activity caused their pupils to dilate.
In the study, the researchers showed that infants who put in more effort looking at cards presented upwards remembered them better and were more likely to find matches. The degree of pupil dilation in infants during cognitive tasks has been shown to be a psychophysiological measure of information processing. And this shows that pupillometry can be used as a measure of cognitive effort in infants. Equally important when it comes to pupillometry research is working memory and its associated cognitive overload.
According to the researchers, this not only allows for more accurate measurement of infants’ memory, but also other cognitive abilities such as higher-level reasoning and decision-making.