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Two distinct visual motion mechanisms for smooth pursuit: evidence from individual differences
Jeremy B Wilmer1, Ken Nakayama
1Department of Psychology, School of Arts and Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA. wilmer@sas.upenn.edu
Neuron
|June 22, 2007
Summary
Smooth-pursuit eye movements improve after a catch-up saccade. This study reveals distinct visual motion signals influence pursuit before and after the saccade, explaining the enhancement.
Area of Science:
- Neuroscience
- Vision Science
- Psychophysics
Background:
- Smooth-pursuit eye movements track moving objects with enhanced accuracy following a catch-up saccade.
- The underlying neural mechanisms for this postsaccadic enhancement remain poorly understood.
Purpose of the Study:
- To investigate whether distinct visual motion signals drive smooth pursuit before and after a catch-up saccade.
- To identify individual differences in visual speed estimation that correlate with pursuit performance.
Main Methods:
- Developed an individual-differences-based method correlating eye-tracking data with psychophysical speed estimation.
- Measured smooth-pursuit eye velocity and its acceleration/precision over time.
- Assessed participants' precision in estimating speed using low-level (motion energy) and high-level (position tracking) visual cues.
Main Results:
- Presaccadic pursuit acceleration correlated with the precision of low-level motion-based speed estimation.
- Postsaccadic pursuit precision correlated with the precision of high-level position-tracking speed estimation.
- These two associations were independent across individuals.
Conclusions:
- Low-level motion signals contribute to presaccadic pursuit acceleration.
- Independent high-level motion signals influence postsaccadic pursuit precision.
- This suggests a dual-signal mechanism underlies the postsaccadic enhancement of smooth pursuit.
