Go to the NASA Homepage
 
Search >
Click to Search
Human Systems Integration Division homepageHuman Systems Integration Division homepage Organization pageOrganization page Technical Areas pageTechnical Areas page Outreach and Publications pageOutreach and Publications page Contact pageContact page
Human Systems Integration Division Homepage
Outreach & Publications Sidebar Header
Go to the Outreach & Publications pageGo to the Outreach & Publications page
Go to Awards pageGo to Awards page
Go to News pageGo to News page
Go to Factsheets pageGo to Factsheets page
Go to Multimedia pageGo to Multimedia page
Go to Human Factors 101 pageGo to Human Factors 101 page
What is Human System Integration? Website
Publication Header
Ocular Pursuit of Flicker-Defined Motion  (1998)
Abstract Header
A moving luminance-defined spot elicits smooth pursuit eye movements which respond rapidly to changes in direction of motion. This study examined eye movements evoked by a 2nd order (non-Fourier) motion target defined by polarity reversal in a binary random texture. On each frame transition (60 Hz), a Gaussian probability density function determined whether the corresponding array element reversed polarity. Moving the density function from frame to frame evoked a vivid percept of motion in spite of the fact that there were no 1st order (Fourier-based) motion cues. Subjects viewed a series of trials in which this flicker-defined spot moved downward at 6 degrees/second, changing direction by 30 degrees (right or left) at a variable point within the trajectory. Eye position was recorded with a video ophthalmoscope having a resolution of 1 minute of arc.

Unlike a luminance-defined spot, these targets do not cause rapid initiation of pursuit. Instead, the eye saccades to the target 4-500 milliseconds after the onset of motion. Following this initial saccade, some smooth motion was seen, perhaps due to prediction. Direction-change events in mid-trajectory were similarly ineffective at driving pursuit, and produced high-latency saccades. These results suggest that flicker-defined motion is seen by perceptual, but not oculomotor pathways.
Private Investigators Header
Authors Header
Groups Header
Keywords Header
Flicker-Defined, Motion, Ocular, Pursuit
References Header
Perception(suppl.), 27, 183
Go to the First Gov Homepage
Go to the NASA - National Aeronautics and Space Administration Homepage
Curator: Phil So
NASA Official: Jessica Nowinski
Last Updated: August 15, 2019