Tutorial 2: Pulforich Illusion Flashcards
What are the three components of the Pulforich Illusion?
- Stereoscopic Vision
- Harmonic motion of pendulum
- Filter/lens
Explain stereoscopic vision
Stereoscopic vision is the process whereby an object is viewed by two eyes with two different images (binocular disparity), in which is combined to then form understanding of the depth and distance of objects in visual mapping.
Explain binocular disparity, uncrossed disparity, and crossed disparity
Viewing objects with two eyes, and thus two different images
- Uncrossed disparity is viewing an object farther away from the focused object
- Crossed disparity is viewing an object closer than the focused object
In an uncrossed disparity event, where does the light appear in the eye
The image appears to the left in position of the left eye, right position in the right eye
In an uncrossed disparity event, looking from both an instance of the right eye and left eye perspective, how does point 2 appear?
When looking from the right eye’s perspective, the second point appears to the right of the first point
When looking from the left eye’s perspective, the second point appears to the left of the first point
In an CROSSED disparity event, looking from both an instance of the right eye and left eye perspective, how does point 2 appear?
When looking from the right eye’s perspective, the second point appears to the left of the first point
When looking from the left eye’s perspective, the second point appears to the right of the first point
In an crossed disparity event, where does the light appear in the eye?
The light appears to the right position of the left eye, left position of the right eye
Why does holding a filter over an eye delay the image? How does this affect viewing a pedulum?
Signal transduction from binocular regions of the brain is fast with bright images, and thus with a filter which dims the light creates a delayed image. Thus, viewing a pedulum object with a filter over one eye means that one eye views an object as delayed, and the other as is
Explain the pulforich illusion
When viewing a pedulum with a filter over an eye that dims lighting, the pedulum will appear as if its going in a circular motion. This is because the filter eyed perceives the object slower than the other eye, and thus an illusion of uncrossed disparity appears when the object crosses from left to right, whilst crossed disparity appears when the object crosses from right to left.
What occurs when the pedulum swings left to right vs. right to left? (With a left eye filter) Accelerating & deccelerating
Left to right: In acceleration, the left filter eye causes increased uncrossed disparity, appearing further away
In decceleration, the left filtered eye views uncrossed disparity decreasing, appearing to come closer
This appears as a backward arc
Right to left: In acceleration, the left filter eye causes increased cross disparity, appearing closer
In decceleration, the left filtered eye views uncrossed disparity decreasing, appearing to go further away.
This appears as a forward arc
What occurs when the pedulum swings left to right vs. right to left? (With a RIGHT eye filter) Accelerating & deccelerating
Left to right: In acceleration, the right filter eye causes increased crossed disparity, appearing closer
In decceleration, the right filtered eye views crossed disparity to decrease, appearing to go further away
This appears as a forward arc
Right to left: In acceleration, the right filter eye causes increased uncross disparity, appearing further away
In decceleration, the right filtered eye views uncrossed disparity decreasing, appearing to go closer.
This appears as a forward arc
Explain occlusion
Occlusion is the process whereby things cover up a part of something else, we know that object must be closer than the one its occluding
