Commentary: Extending the Ideal Observer Approach
Velma Dobson University of Pittsburgh
Throughout the history of research in visual development, a variety of mechanisms have been hypothesized to underlie the developmental changes in vision that occur between birth and adulthood. Bronson ( 1974), for example, suggested that the visual responses of the newborn are based on subcortical pathways, and that the changes seen in the quality of visual responses during infancy are the result of the maturation of cortical pathways. Maurer and Lewis ( 1979) also emphasized the importance of cortical maturation. However, they suggested that visual responses in early infancy are mediated by the X pathway to the visual cortex and the Y pathway to the superior colliculus and pretectum, and that the changes in visual responsiveness that occur during infancy are the result of maturation of the Y pathway to the cortex.
The ideal observer approach to visual development, described by Banks and Shannon in their chapter (this volume) and previously by Banks and Bennett ( 1988), provides an exciting, new way to look at the mechanisms that may underlie the deficits in vision shown by infants. This approach concentrates on the "front end" of the visual system, and reminds us that developmental changes in visual responsiveness may have nothing to do with cortical maturation. They may, instead, be related to maturational changes in the structure of the eye and the photoreceptors that influence visual input long before it reaches visual cortex.