Every time we move our eyes, a new image is recorded at the back of our eye (i.e., the retina). However, we seldom perceive this change in the visual world despite frequent eye movements or saccades. How we maintain stable perception of the world is then a critical yet complex question which is fundamental to understanding our visual system and cognitive processes.
Target localization across saccades
Spatial information is initially processed on the retina as retinotopic (eye-centered) location. On the other hand, our daily cognitive tasks (e.g., finding keys on a table) often require spatiotopic (world-centered) location. This means that we frequently need to translate retinotopic coordinates into spatiotopic coordinates across saccades. There are many ways we use to link the retinal information before and after a saccade to get stable perception, and nontarget objects as “landmarks” are one of them. My research has shown that the presence of nontargets both facilitate and biases target localization across saccades, by providing relational information in space.
Covert attention across saccades compared to during sustained fixations
We can direct our visual spatial attention by covertly attending to relevant locations, moving our eyes, or both simultaneously. Attention shifting has been found to share underlying brain mechanisms with saccades. It is then an interesting question how shifting versus holding covert attention during fixations compares with maintaining covert attention across saccades; that is, how retinotopic and spatiotopic attention compares with shifting versus holding covert attention at fixations, regarding their brain representations.
Decoding 3D spatial locations across saccades
The signals processed on our retina is two-dimentional. But our world has a third dimension, depth, which also needs to be reconstructed from retinal inputs. How is our perception of depth maintained across saccades? By recording participants brain activities while viewing a stimulus that appeared in one of the 3D screen locations, we are able to examine the representations of 3D spatial locations in the brain, and investigate whether/how they change across saccades.