Synopsis Of Research:
When we turn our eyes to look at a stationary target or to follow a moving target, the eye movement causes a shift in the retinal image of objects in the visual environment. An expectation about this shift might be that there should also be a corresponding shift in the perceived visual location of an object. However, under normal visual circumstances this is not the case, i.e., the perceived location of the object remains stable. How, in the face of the retinal image shift, is this possible? A traditional viewpoint is that an extraretinal signal, coming from the oculomotor system, is generated along with the eye movement, and in some manner this signal serves to cancel out what otherwise would be a change in the perceived location. Current research in this laboratory is concerned with the processes underlying perceived location around the time of an eye movement. In particular, the research has concentrated on use of theoretical models to explore the manner in which a retinal signal might interact with the extraretinal signal, and the effects of this interaction on perception. As an example, most investigations in this area are about the perceived location of a flash presented before, during and following the occurrence of a saccadic eye movement. An assumption implicit in such research is that the perceived location of the flash is an accurate reflection of the features of the extraretinal signal. However, what is usually ignored is that a flash gives rise to long duration retinal signal persistence (200 to 300 msec). The models developed in this laboratory suggest that retinal signal persistence interacting with the extraretinal signal result in an apparent extraretinal signal whose onset time and temporal features are different from those of the actual extraretinal signal. Some current research issues under investigation include: a) the onset time of the extraretinal signal relative to saccadic eye movement; b) the perception of two or more successive perisaccadic flashes; c) the perception of a flash in the face of a continuous background stimuli; d) the mechanism underlying perisaccadic compression of visual space; and e) perceived location during smooth pursuit eye movement. The intent of this work is not only to provide an account of psychophysical data but also to reveal the functional properties of underlying neurophysiology.

Current Or Representative Publications:

Pola J. A model of the mechanism for the perceived location of a single flash and two successive flashes presented around the time of a saccade. Vision Research 2007; 47: 2798-2813.

Pola J. Development of eye movements in infants, in R Duckman (Ed.) Visual Development, Diagnosis, and Treatment of the Pediatric Patient. Lippincott Williams and Wilkins 2006.

Pola J. Models of the mechanism underlying perceived location of a perisaccadic flash. Vision research 2004; 44: 2799-2813.

Pola J. Models of the saccadic and smooth pursuit systems, in G K Hung and K J Ciuffreda (Eds.) Models of the Visual System. Kluwer Academic/Plenum Publishers 2002.

Pola J. and Wyatt H. J. The role of target position during pursuit deceleration and termination. Vision Research 2001; 41: 655-669.