Perception lecture 1.5 Depth.pdf

Foundations of Perception and Cognition Binocular vision and depth perception Dr Deanne Green  We acknowledge and pay our respects to the Kaurna people, the traditional custodians whose ancestral lands we gather on. We acknowledge the deep feelings of attachment and relationship of the Kau...

Foundations of Perception and Cognition Binocular vision and depth perception Dr Deanne Green  We acknowledge and pay our respects to the Kaurna people, the traditional custodians whose ancestral lands we gather on. We acknowledge the deep feelings of attachment and relationship of the Kaurna people to country and we respect and value their past, present and ongoing connection to the land and cultural beliefs. Perception Lectures What will you learn 1. Intro to sensation and perception 2. Methods 3. Spatial vision 4. Body senses 5. Depth perception 6. Motion perception Depth perception Part 1 Monocular cues Binocular cues Depth perception Binocular disparity Knowing where we are in Space The body senses Ø Proprioceptive & somatosensory systems Ø The Vestibular system Depth perception Ø Judgement of the location of objects in depth Depth perception The world is three dimensional Yet we gather two dimensional information through the eyes. How do we perceive the world as three dimensional? Depth perception Monocular cues Ø Texture gradient Ø Size Ø Occlusion Binocular cues Ø Vergence Ø Stereo Texture gradient Retinal Size Size consistency Size consistency Size consistency Size consistency Size consistency Occlusion Occlusion Depth perception Monocular cues Ø Texture gradient Ø Size Ø Occlusion Binocular cues Ø Disparity Ø Convergence Binocular disparity On average, the pupils are approximately 6.3 cm apart This means that each eye provides a slightly different view of the world. These differences provide a very useful cue to depth – binocular disparity Binocular disparity Slide 19 View from left eye View from right eye Slide 20 Video Convergence; far and near disparity Convergence; far and near disparity Far (uncrossed) disparity: Non-fixated point is further away, and the right eye’s view of the point is shifted right relative to the left eye’s view Near (crossed) disparity: Non-fixated point is nearer away, and the right eye’s view of the point is shifted left relative to the left eye’s view Convergence; far and near disparity True depth (m) Disparity (arcmin) Testing depth perception Part 2 RanDot Stereo test Binocular rivalry Random dot stereogram Developed by Bela Julesz Demonstrates how stereo vision is perceived (in the brain) Demonstrates that stereoscopic depth is perceived in the absence of contextual cues About 5% of people cannot see the depth in random-dot stereograms Random dot stereogram Left eye view Right eye view Random dot stereogram Left eye view Right eye view Autostereogram (magic eye 3D art) Autostereogram (magic eye 3D art) Our view of the world Slide 31 Binocular Rivalry Slide 32 Binocular Rivalry Slide 33 Binocular Rivalry Slide 34 Summary References Snowden, R., Thompson, P & Troscianko, T (2006): Basic Vision Oxford University Press, Oxford. Chapter 7 Mather, G (2016): Foundations of sensation and perception Psychology Press Ltd., Hove Chapters 11