Visual Backward Masking in Young Infants

Article: Babies Can See Things Adults Can't Due to Visual Masking Phenomenon
Source: Chuo University (Japan), in Technology Networks
Published: June 28, 2021

Adorable illustration explaining that infants younger than
7 months perceive the face even when followed by the contour
mask, while infants older than 7 months and adults do not

Visual perception begins in the retina and is serially processed in increasingly higher levels of the visual cortex in a bottom-up manner. However, top-down feedback is also sent from higher to lower visual areas. Researchers in Japan interested in the interference of this feedback processing in the brain studied visual backward masking in infants ages 3 to 8 months. Visual backward masking occurs when the perception of a second object masks the perception of an immediately preceding object. This phenomenon occurs even if the second object does not spatially overlap the first object, such as a contour or four dots surrounding the object in the present experiments. To test visual perception in infants, the researchers presented them with images of faces on a computer screen and measured the time they spent looking at the images, taking into account that infants look longer at faces (compared to other images). The faces were presented in two conditions: followed by a mask image and followed by nothing. They discovered that infants ages 7 to 8 months, similar to adults, could not see the faces if followed by a mask image, indicating that backward masking had occurred. In contrast, infants ages 3 to 6 months could perceive the faces even if they were followed by the mask. This indicates that visual backward masking did not occur, suggesting that feedback processing is immature in the brains of infants younger than 7 months of age. The study's first author explains, "[Y]ounger infants do not have feedback processing that backward masking should interfere, and thus, masking is ineffective for them." In the latter half of their first year of life, top-down processing begins to take effect to provide that feedback, which becomes important in robustly perceiving ambiguous visual input. As another author proffers, "In return for susceptibility to visual masking, we acquire the ability to robustly perceive ambiguous visual scenes."

My rating of this study: ⭐⭐

Nakashima Y, Kanazawa S and Yamaguchi MK. "Perception of invisible masked objects in early infancy." PNAS.  118(27):e2103040118. 6 July 2021. https://doi.org/10.1073/pnas.2103040118