Fundraiser Concert for Haiti • U of L Students and Faculty Performing – 9pm Blues Sen-sa-shun – 10pm Shawna Romolliwa – 11pm Dave Renter • At The Slice, Friday Feb. 26 th – $5 for students, $10 for everybody
Feb 22, 2016
Fundraiser Concert for Haiti
• U of L Students and Faculty Performing
– 9pm Blues Sen-sa-shun
– 10pm Shawna Romolliwa
– 11pm Dave Renter
• At The Slice, Friday Feb. 26th – $5 for students, $10 for everybody else
Extra Credit for Participating in Experiments
Go to www.tatalab.ca to sign up
We are recruiting for a variety of experiments including basic
perception and ADHD
Upcoming
• Gregory Article for today
• Read Pinker Article for help with stereo vision and stereo grams
• Read Land Article for March 2
Depth Cues Pictorial Depth Cues: aspects of 2D images that imply depth Physiological Depth Cues: Proprioception in ocular muscles indicates
accommodation and convergence Motion Depth Cues: foreground and background move in opposite directions Stereoscopic Depth Cues: disparity between two retinal images indicates
distance
Illusions related to depth perception
• Misperceptions of size• Misperceptions of location
Muller - Lyer Illusion
Muller - Lyer Illusion
Muller-Lyer Illusion
• What theory does Gregory take up?
Muller-Lyer Illusion
• What theory does Gregory take up?– Thiery / Woodworth : Muller-Lyer figure
“suggests perspective”
Muller-Lyer Illusion
• What theory does Gregory take up?– Thiery / Woodworth : Muller-Lyer figure
“suggests perspective”
– Is there something about the presence of pictorial depth cues in an image that distorts size?
Depth Cues and Size Distortion
The Ponzo Illusion:
Depth Cues and Size Distortion
The Ponzo Illusion:
Depth Cues and Size Distortion
• The illusion of depth in an image seems to distort the perception of size in the image
• This is due to misapplication of Size - Constancy
Pictures are Weird
• What does Gregory find paradoxical about pictures?
Pictures are Weird
• What does Gregory find paradoxical about pictures?
Pictures convey depth yet also appear flat
Why?
Pictures are Weird
• When you view a picture there are some depth cues telling you to perceive depth, but other cues telling you that the image is on a flat surface
• …the surface matters!
• Retinal image size
Pictures are Weird
• Retinal image size
Pictures are Weird
The Apparatus
• What does he do to remove the paradox so that the Muller-Lyer figure no longer looks flat?
• Remove the background surface
The Apparatus
Removing the Background
• With background removed, Muller-Lyer figure actually looks 3D
• What prediction can you make about how the perceived size and the perceived distance of the center line are related?
Removing the Background
• With background removed, Muller-Lyer figure actually looks 3D
• What prediction can you make about how the perceived size and the perceived distance of the center line are related?
When the centre line appears close,it should also appear smallWhen the centre line appears far, it should also appear large
Removing the Background
• How did Gregory test that?
The Apparatus
Removing the Background• Perceived size and perceived distance are tightly
related• inward arrowheads make line look closer / outward
arrowheads make line look farther
Misperception of Depth Drives Other Illusions
• Ames Room view from above
• Ames Room Video
Autostereograms: The Magic Eye
Binocular Disparity
• points nearer than horopter have crossed disparity
• points farther than horopter have uncrossed disparity
The Horopter
Stereograms
• seeing depth requires “only” two different images on the retina
Stereograms• seeing depth requires “only” two
different images on the retina
• this could be accomplished by an optical device that projects separate images into the two eyes
Presenting Binocular Images
• Various ways to add depth:– 1. Stereoscope
Presenting Binocular Images
• Various ways to add depth:– glasses with different lenses
Presenting Binocular Images• Various ways to add depth:
– glasses with different lenses
Presenting Binocular Images• Various ways to add depth:
– glasses with different lenses
Stereograms
Left Eye Right EyeDivider
• Right eye sees face to the right; left eye sees face to the left therefore:
uncrossed disparity
• Face appears behind the square
Stereograms
Left Eye Right EyeDivider
What would you see?
Stereograms
Left Eye Right EyeDivider
• Right eye sees face to the left; left eye sees face to the right therefore:
crossed disparity
• Face appears in front of square