Introduction ICS 280 Visual Perception Aditi Majumder Perception is taken for granted Slide 2 ICS 280 Visual Perception 1 Perception is very complex Perceive Locate Identify Recognize Different objects Their relationship with each other Qualitative and Quantitative Act based on these information It is a miracle that we do not cause accidents mistakes every now and then Slide 3 ICS 280 Visual Perception Perceptual Process Knowledge Perception Processing Transduction Stimulus on Receptors Recognition Action Environmental Stimulus Attended Stimulus Slide 4 ICS 280 Visual Perception 2 Perceptual Process Knowledge Perception Recognition Processing Action Transduction Environmental Stimulus Stimulus on Receptors Attended Stimulus Slide 5 ICS 280 Visual Perception Environmental Stimulus Anything in our environment that we can perceive Can be anything we can sense See hear touch smell Mary goes to circus Slide 6 Takes seats observes animal in center stage trapeze on the ceiling band on the right clowns in the side Constitutes the environmental stimulus ICS 280 Visual Perception 3 Perceptual Process Knowledge Perception Processing Recognition Action Transduction Stimulus on Receptors Environmental Stimulus Attended Stimulus Slide 7 ICS 280 Visual Perception Attended Stimulus A part of the environmental stimulus Focuses attention on this stimulus Mary focus her attention on the center stage animal by looking at it directly Slide 8 ICS 280 Visual Perception 4 Perceptual Process Knowledge Perception Processing Recognition Action Transduction Environmental Stimulus Stimulus on Receptors Attended Stimulus Slide 9 ICS 280 Visual Perception Stimulus on Receptors The attended stimuli excites the receptors For example Visual stimulus forms a image on the retina Sound changes pressure to affect the ear drum Note Slide 10 We do not perceive the image on the retina It is just one of the initial steps of the process ICS 280 Visual Perception 5 Perceptual Process Knowledge Perception Recognition Processing Action Transduction Stimulus on Receptors Environmental Stimulus Attended Stimulus Slide 11 ICS 280 Visual Perception Transduction Transformation of one form of energy to other Environmental energy transformed to electrical energy The image on the retina generates electrical signals in the tens and thousands receptors of the eye Slide 12 ICS 280 Visual Perception 6 Perceptual Process Knowledge Perception Processing Recognition Action Transduction Stimulus on Receptors Environmental Stimulus Attended Stimulus Slide 13 ICS 280 Visual Perception Neural Processing Neurons are elements of nervous system Interconnected together Processing of the electrical energy by the neurons while they travel through them Slide 14 This changes the electrical energy in various ways ICS 280 Visual Perception 7 Perceptual Process Knowledge Perception Recognition Processing Action Transduction Stimulus on Receptors Environmental Stimulus Attended Stimulus Slide 15 ICS 280 Visual Perception Perception Conscious sensory experience Electric energy transforms in brain to some experience Is this the end of perception Slide 16 Recognition and action are important outcomes of the perceptual process ICS 280 Visual Perception 8 Perceptual Process Knowledge Perception Recognition Processing Action Transduction Environmental Stimulus Stimulus on Receptors Attended Stimulus Slide 17 ICS 280 Visual Perception Recognition Identifying the experience as something Known Similar to some experience before If this fails people may be in grave trouble Slide 18 Visual form of agnosia ICS 280 Visual Perception 9 Visual form of agnosia Dr P found he cannot recognize students but can tell their name from their voices Started conversation with parking meters or expected furniture to talk to him Was he blind Inability to recognize objects due to a tumor in brain When show a gloves he told Eye examination showed no problem a continuous surface unfolded by itself with five outpouchings Maybe a container or a purse to keep coins to different sizes He can perceive an object identify parts of it but cannot assemble the parts perceptually to recognize it Slide 19 ICS 280 Visual Perception Perceptual Process Knowledge Perception Processing Transduction Stimulus on Receptors Recognition Action Environmental Stimulus Attended Stimulus Slide 20 ICS 280 Visual Perception 10 Action Goal of perception is to create action Evolutionary reason for development of perception Motor activities Response to perception and recognition Leads to New attended stimulus Whole cycle repeats Slide 21 ICS 280 Visual Perception Perceptual Process Knowledge Perception Processing Transduction Stimulus on Receptors Recognition Action Environmental Stimulus Attended Stimulus Slide 22 ICS 280 Visual Perception 11 Knowledge Affects Identification from memory Processing Perception Recognition Old knowledge Recent knowledge Mary s example Slide 23 Compare the image of tiger with the conception of tiger in her memory Retrieve the name tiger that goes with it ICS 280 Visual Perception Cognitive Influences on Perception Slide 24 ICS 280 Visual Perception 12 Cognitive Influences on Perception Slide 25 ICS 280 Visual Perception Visual Perception Vision plays preeminent role for humans Evolutionary history Vision was developed to aid survival and successful reproduction Slide 26 Used to get nourishing food safe shelter and strong mates ICS 280 Visual Perception 13 Why Vision is so Important Vision is preeminent Only sense that provides accurate spatial information from a distance Smell and hearing provides information from a distance but not accurate Touch and taste provide very accurate information but only on contact Vision helps us most to keep away from danger Vision is a veridical perception What you see is what you get Slide 27 ICS 280 Visual Perception Studying Perceptual Process Levels of Analysis At different scales Bottom Up Top Down Starting from the stimulus towards perception Starting from knowledge We will study both and cross refer Slide 28 ICS 280 Visual Perception 14 Studying Perceptual Process Psychophysical Relationship between stimulus and perception What Physiological Relationship between the processes within a person and perception How Slide 29 ICS 280 Visual Perception Psychophysical Approach Description Recognition Detection Magnitude Search Slide 30 ICS 280 Visual Perception 15 Psychophysical Approach Description Recognition Qualitative Used by doctors Detection