3. Pursuits - Eye Movements & Binocular Vision Summer 2026

What is a pursuit?

-Gaze-shifting eye movements

-Slow, conjugate tracking eye movement in response to a moving stimulus

What is the primary stimulus for a pursuit?

target velocity

What is the goal of a pursuit?

-Match the eye velocity with the target velocity

-Stabilize the object of interest on the retina

-To create a constant oculocentric direction (β)

A ______ is our stimulus to generate or adjust a pursuit eye movement

non-zero rate of change of β

What is the goal of a pursuit?

to adjust eye velocity (rate of change of ocular direction -- α) so that β is constant

What is the latency period for a pursuit?

100 +/- 5msec

Pursuit velocity will closely match what?

target velocity up to 60-70º/sec

Above 60-70º/sec, pursuits are usually (slower/faster) than target velocity

slower

Pursuits can keep up with targets moving up to _______º/sec in some instances

100-150

(Vertical/horizontal) pursuits are more accurate than (Vertical/horizontal) pursuits

horizontal; vertical

If eyes are BEHIND the target, this may trigger a saccadic eye movement called a ________

catch up saccade

Catch-Up Saccade Diagram (Pic)

Catch-Up Saccade Diagram (Pic)

Catch-Up Saccade Diagram (Pic)

Catch-Up Saccade Diagram (Pic)

Catch-Up Saccade Diagram (Pic)

Catch-Up Saccade Diagram (Pic)

Performance of pursuits (increases/decreases) with age

decreases

What increases as we age?

error correcting or catch up saccades

Knowledge of the target allows _______ as to its future behavior

educated guesses

What happens to pursuits when patients can make educated guesses about future target behavior?

patients can track objects more accurately

What does the Bode Analysis for Pursuits contain?

2 plots (just like for VOR)

What are the 2 Bode plots that describe Pursuits?

-Gain vs frequency

-Phase vs Frequency

What is the ideal phase of pursuits?

0º

Bode Plots (Pic)

Bode Plots (Pic)

Are we able to train pursuits?

Several studies show that is it possible to train pursuits. After 7.5 min subjects learned to track an odd target movement. Included 3 Pirate baseball platers who had much lower initial tracking errors than other subjects; however after training, all subjects plateau at some final error score

How do drugs affect pursuits?

Barbiturates can eliminate smooth pursuits but leave saccadic intact. To follow a target, patients have to make a series of saccadic movements

You can only pursue a baseball until about ______

10 ft

When measuring VA with a moving target, what eye movement is utilized?

pursuits -- in an attempt to stabilize the retinal image and thus provide better resolution