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Express attentional shifts
1Smith Kettlewell Eye Research Institute, San Francisco, CA 94115.
Vision Research
|January 1, 1993
Summary
Rapid attention shifts explain "express" saccades, which have very short latencies. The disappearance of a fixation cue, particularly in a gap paradigm, facilitates faster attention deployment, leading to quicker eye movements.
Area of Science:
- Neuroscience
- Cognitive Psychology
- Ophthalmology
Background:
- Express saccades exhibit extremely short latencies.
- These saccades are more frequent when a gap exists between fixation mark disappearance and target appearance.
- Hypotheses suggest attention movements precede eye movements, with fixation mark removal aiding attention disengagement.
Purpose of the Study:
- To investigate the role of attention shifts in the generation of express saccades.
- To provide direct evidence for the hypothesis that rapid attention shifts underlie short saccadic latencies.
Main Methods:
- Attention was measured using extra-foveal vernier acuity.
- Comparison of performance in gap versus no-gap paradigms with varying cue lead times.
- Control experiments to isolate the effect of fixation mark disappearance.
Main Results:
- Performance improved faster with increasing cue lead times in the gap paradigm.
- The relationship between gap duration and discrimination performance mirrored that of gap duration and express saccade rate.
- Fixation mark disappearance, not a general warning, accelerated attention shifts.
Conclusions:
- The short latencies of express saccades are likely mediated by rapid attention shifts.
- The findings support the model where attention disengages and deploys faster when the fixation cue is removed.
- This mechanism explains the increased frequency of express saccades in gap paradigms.