So What Has So, What Has So, What Has So What Has Vision Done For Vision Done For Vision Done For Vision Done For Me Lately? Me Lately? Me Lately? Me Lately? Prepared for ICBO Prepared for ICBO Prepared for ICBO Prepared for ICBO Ontario, CA Ontario, CA By: R. A. Hohendorf OD By: R. A. Hohendorf OD April 2010 April 2010
Why do we need vision? Why do we need vision? Why do we need vision? Why do we need vision? “We need vision for two We need vision for two two quite different two quite different “We need vision for We need vision for quite different quite different but complementary reasons reasons but complementary We need vision to give us detailed knowledge We need vision to give us detailed knowledge We need vision to give us detailed knowledge We need vision to give us detailed knowledge of the world beyond ourselves of the world beyond ourselves – – knowledge knowledge t at a o that allows us to recognize things from minute t at a o that allows us to recognize things from minute s us to ecog s us to ecog e t e t gs gs o o ute ute to minute and day to day to minute and day to day We also need vision to guide our actions in We also need vision to guide our actions in g that world at the very moment they occur” that world at the very moment they occur”
Definition Of Vision Definition Of Vision Definition Of Vision Definition Of Vision Vision is the deriving of meaning and Vision is the deriving of meaning and Vision is the deriving of meaning and Vision is the deriving of meaning and direction of action as triggered by light direction of action as triggered by light It is our dominant sensory system It is our dominant sensory system It is our dominant sensory system It is our dominant sensory system It is a pervasive process of the human being It is a pervasive process of the human being It is not accommodation, convergence, It i It i It is not accommodation, convergence, t t d ti d ti depth perception, visual closure, eyesight, depth perception, visual closure, eyesight, visual acuity nor visual fields visual acuity nor visual fields i i l l it it no no i i l field l field These are some parts of the visual process These are some parts of the visual process Vision is more than the sum of its parts Vision is more than the sum of its parts
A Communication Tool A Communication Tool Principles Supported By Modern Neuro Principles Supported By Modern Neuro- -Science Science
Vision as an Emergent Vision as an Emergent Vision as an Emergent Vision as an Emergent An emergent is more than the sum of its An emergent is more than the sum of its An emergent is more than the sum of its An emergent is more than the sum of its parts parts Vision is not the only emergent Vision is not the only emergent Vision is not the only emergent Vision is not the only emergent Vision is a continuum in constant flux Vision is a continuum in constant flux Visual memory is our past Visual memory is our past Eyesight is the present Eyesight is the present Visual imagery is the possibilities of the future Visual imagery is the possibilities of the future
Parts Parts Parts Parts The problem with looking at parts and The problem with looking at parts and The problem with looking at parts and The problem with looking at parts and reductionist thinking reductionist thinking Clock example (thank you Rob Lewis) Clock example (thank you Rob Lewis) Clock example (thank you Rob Lewis) Clock example (thank you Rob Lewis) Vision in particular is very difficult to look Vision in particular is very difficult to look at parts and understand in its complexity at parts and understand in its complexity t t t t d d d d t t d i d i it it l l it it Vision is an Emergent Vision is an Emergent
Interesting Visual Perspectives Interesting Visual Perspectives Interesting Visual Perspectives Interesting Visual Perspectives We sample things visually at 3 We sample things visually at 3 We sample things visually at 3-5 times per We sample things visually at 3 5 times per 5 times per 5 times per second yet our perception is constant second yet our perception is constant We see things after they have happened We see things after they have happened We see things after they have happened We see things after they have happened The power of visual imagery and The power of visual imagery and anticipation anticipation anticipation anticipation Visual motor skill exception Visual motor skill exception
Anticipation Anticipation Anticipation Anticipation “Experiments that have tested people’s “Experiments that have tested people’s reaching and grasping under monocular reaching and grasping under monocular reaching and grasping under monocular reaching and grasping under monocular viewing conditions have shown that the viewing conditions have shown that the reaches are much slower more tentative reaches are much slower more tentative reaches are much slower, more tentative reaches are much slower, more tentative and less accurate than the same and less accurate than the same movements made under normal binocular movements made under normal binocular movements made under normal binocular movements made under normal binocular viewing conditions. It is binocular viewing conditions. It is binocular information that allows us to make information that allows us to make information that allows us to make information that allows us to make grasping movements that are calibrated grasping movements that are calibrated correctly for distance and tailored to the correctly for distance and tailored to the correctly for distance and tailored to the correctly for distance and tailored to the real size of the object.” real size of the object.”
Binocularity and Grasping Binocularity and Grasping Binocularity and Grasping Binocularity and Grasping “Our hand and “Our hand and “O “O h h d d d d fingers adopt the fingers adopt the final posture of the final posture of the final posture of the final posture of the grasp well before grasp well before we make contact.” we make contact.” “At about 2/3rds “At about 2/3rds the way to the the way to the object begin to object begin to object begin to object begin to close in on the close in on the object.” object.”
A Review Of The Visual A Review Of The Visual Pathway (The Parts) Pathway (The Parts) Known Pathways Known Pathways Known Pathways Known Pathways Magnocellular and Parvocellular Pathways Magnocellular and Parvocellular Pathways Visual Attention Visual Attention Vi Vi l Att l Att ti ti Metrics Metrics
Visual Pathways Visual Pathways Visual Pathways Visual Pathways
Magno and Parvo Magno and Parvo Magno and Parvo Magno and Parvo Two types of retinal cells that send input Two types of retinal cells that send input Two types of retinal cells that send input Two types of retinal cells that send input to the brain to the brain Magno Magno Magno Magno Fast Fast Large receptive fields L L Large receptive fields ti ti fi ld fi ld Motion detection Motion detection Mid brain and posterior parietal projection Mid brain and posterior parietal projection
Magno and Parvo Magno and Parvo Magno and Parvo Magno and Parvo Parvo Parvo Parvo Parvo Slower (relatively speaking) Slower (relatively speaking) Smaller receptive cells Smaller receptive cells Smaller receptive cells Smaller receptive cells Color Color V1 projection V1 projection V1 projection V1 projection Tiling Concepts Tiling Concepts
Rod and Cone Retinal Rod and Cone Retinal Distribution Distribution
M & P Cell M & P Cell Absolute Absolute Absolute Absolute Densities in the Densities in the Retina Retina From From E.Hussey E.Hussey JBO JBO Vol Vol 14/2003 14/2003 “Speculations on the “Speculations on the nature of visual motion nature of visual motion – – optometric implications optometric implications
Magno and Parvo Myths Magno and Parvo Myths Magno and Parvo Myths Magno and Parvo Myths Rod and Cone myths: Rod and Cone myths: Rod and Cone myths: Rod and Cone myths: All magnocellular cells are rods All magnocellular cells are rods All parvocellular cells are cones All parvocellular cells are cones All parvocellular cells are cones All parvocellular cells are cones Central and Peripheral Vision myths: Central and Peripheral Vision myths: All central visual field cells are cones All central visual field cells are cones ll ll l l l f l f ld ld ll ll All Peripheral visual field cells are rods All Peripheral visual field cells are rods Dorsal and Ventral Pathway myths: Dorsal and Ventral Pathway myths: All magnocellular cells are dorsal stream cells All magnocellular cells are dorsal stream cells All parvocellular cells are ventral stream cells All parvocellular cells are ventral stream cells
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