Visual Perception By Katie Young and Joe Avery

Overview Visual Perception Eye Trackers Change Blindness

What is Visual Perception? Information reaching the eyes Planning action Eyesight

Visual Perception Lab Understanding of the visual system Images and the environment Decision-making and actions

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The Visual Perception Lab Human eye only accurate in small area Humans make over 100,000 saccades everyday

The Visual Perception Lab Study eye movements Experiments Eyetrackers

Measures eye positions and movements Record eye movements during tasks We used three different eyetrackers

Eye

Eyetrackers Wearable Eyetracker ASL E6000 Eyetracker Dual Purkinje

Video Based Eyetrackers Wearable and ASL E6000 Use light reflections off of eye Pupil and corneal reflection

Wearable Eyetracker…. Uses infrared illuminator and miniature camera to capture pupil Uses a second miniature scene camera Off-line analysis

Video-based Eye Trackers

Calibration for Wearable Eyetracker Eyetracking software and hardware Tracks the pupil and corneal reflection Creates a cross hair on scene video

ASL E6000 Eyetracker Head and camera are stationary Calibration is done prior to task We can watch where subject looks during task

Dual-Purkinje Eyetracker Uses mirrors and lenses First and fourth Purkinje (reflection) Very accurate

Definitions Change Detection The observation, identification and location of a changing stimulus. Change Blindness The inability to detect obvious changes in a scene.

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What causes change blindness? The phenomenon of change blindness is caused by limitations in our ability to internally represent what we see; we retain our rich internal representations of what we see for only a second.

Focus Participant’s Attention

Occurrence This occurs when a transient event (like a flash of light, a blink or an eye movement) occurs at the same time as the change in the image

Visual Perception Lab The VPL at RIT performs the repeated-change technique (flicker) as a means to collect data on change blindness. The VPL is currently running experiments on participants to further the knowledge on change blindness.

Why eyetrack? Participant’s Attention

What This Data is Used for The existence of change blindness is a key reason that cell phone use is illegal while driving a vehicle. Simple distractions such as cell phone use are enough for your eye to not notice changes in your field of view.

Acknowledgements Dr. Jeff Pelz Dr. Andrew Herbert Everyone in the Visual Perception Lab