Eye Movement Control and Visual Stability: New Findings in Saccadic
Behaviors of People with Tunnel Vision

Gang Luo
Schepens Eye Research Institute
Boston


Salient visual features have been long regarded as important and primary
stimuli that elicit saccades, yet some scientists argue that many of
hundreds of thousands saccades in natural situations are driven by top-down
information. The two types of saccades presumably are generated through
different visual pathway. This debate led us to examine how the saccadic
eye movements would alter if one only has a very small visual field,
limiting the possible role of visual saliency.

We found that people with tunnel vision made saccades to locations beyond
their pre-saccadic field of views once or twice per second. The size of
their saccades was almost the same as normally sighted people. We believe
this is a strong piece of evidence in support the top-down eye movement
control model. I will discuss the rational and mechanism the finding may
suggest.

Another interesting finding is that, when their pre- and post-saccadic
views do not overlap at all, they do not perceive any sudden image change
or jumping, just as normally sighted people perceive a stable world across
saccades. The trans-saccadic integration theories fail to explain the
phenomenon, because in the case there is no trans-saccadic memory to be
carried over saccades. I will propose a new theory to explain the visual
stability, which emphasizes the blind nature of intra-saccadic perception.