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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 else. Extra Credit for Participating in Experiments. Go to www.tatalab.ca to sign up
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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 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!
Pictures are Weird • Retinal image size
Pictures are Weird • Retinal image size
The Apparatus What does he do to remove the paradox so that the Muller-Lyer figure no longer looks flat? Remove the background surface
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 small When the centre line appears far, it should also appear large
Removing the Background How did Gregory test that?
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
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 Divider Left Eye Right Eye • Right eye sees face to the right; left eye sees face to the left therefore: • uncrossed disparity • Face appears behind the square
Stereograms Divider Left Eye Right Eye What would you see?
Stereograms Divider Left Eye Right Eye • Right eye sees face to the left; left eye sees face to the right therefore: • crossed disparity • Face appears in front of square