Eye-tracking allows us to determine where on a computer screen a child’s gaze is fixated at any given moment. This monitor-mounted system works by reflecting a dim infrared light onto the eye and recording the reflection pattern with a sensor system. Geometric models are then used to calculate the baby’s exact point of gaze.
The Positive Science system is a head-mounted eye-tracker that allows us to record where babies are looking in their natural settings. A soft, stretchy hat is placed over the baby's head, and two cameras are attached with Velcro. One camera is positioned over the baby's forehead, producing an image of his or her field of view. The second camera captures the baby's eye, allowing us to determine where the baby is looking. For some studies the child’s parent wears a second set of cameras on a pair of glasses so researchers can study social interactions between parents and children.
Tablets allow researchers to measure the preferences and responses of pre-literate children in engaging and interactive formats. In these studies, children typically watch movies on the screen, and then respond to verbally or visually presented questions via touch.
Near-infrared spectroscopy (NIRS) is a brain-imaging technology that uses near-infrared light sensors to measure cortical activity in the brain. Unlike other methods of measuring neural activity that require subjects to remain still (e.g., fMRI), NIRS can be used while young children are sitting upright and moving freely. The near-infrared lights and light sensors are snapped into a lightweight velcro cap worn by the infant during studies.
Computational modeling is another tool we use to study early cognitive development. The process involves building a mathematical model designed to simulate a particular human behavior, and then running that model on a computer. This technique allows us to explore and visualize the functional organization of mental events that we can’t directly observe. Several different types of modeling can be used to study human behavior.