Sensation and Perception Reading assignment Chapter 4 pp 126 130 151 159 Objectives 1 Be able to define and differentiate between sensation and perception Sensation refers to the detection of physical energy by our sense organs Perception brain s interpretation of sensory input 2 What is transduction What are sensory receptors How do they work together Transduction the process by which external stimuli is converted into electrical signals within neurons Sense receptors specific reception of each of our five senses transduces specific stimuli Ex Vision light transduced into neural signals by specialized sense receptors called photoreceptors 3 What is psychophysics What is absolute threshold Be able to give an example What is just noticeable differences Be able to give an example What is Weber s law Psychophysics defined study of how we perceive sensory stimuli based on their physical characteristics Absolute threshold the lowest level of sensory stimulis we can detect on 50 of trials Ex At what amplitude does one hear a sound 50 for a given frequency 4 What are the three things our brain integrates to perceive What do we often sacrifice to perceive Just noticeable difference smallest change in intensity of sensory stimuli we can detect Weber s law constant proportional relationship between JND and original intensity Perception Our brain integrates sensory data into meaningful concepts Brain perceives by integrating 1 What s currently in our sensory field 2 What was there a moment ago 3 What we remember from our past Ex Reading Often we sacrifice small details for the bigger picture 5 What is parallel processing What is cross modality What is the McGurk effect and how does it demonstrate cross modality What is synthesia Parallel Processing can attend to multiple senses at the same time Cross modality processing info from multiple senses that produces a different perception than that of any one sense Ex McGurk Effect video of ba fa Synthesia extreme version of cross modality 6 Be able to define and differentiate between top down processes and bottom up processes What are each of these processes driven by Bottom up processes sensory detection encoding construction of whole from parts Lines angles shapes colors 7 What are three reasons that top down processing is so important Top down process conceptually driven organization interpretation of information Past experiences expectations and context 1 Allows us to focus on whats important 2 Allows us to process our environment quickly 3 More efficient 8 What are perceptual sets Be able to give an example Perceptual Sets occur when our expectations influence our perceptions 9 What is perceptual constancy What are the three types of perceptual constancy Be able to define and give an example of each Perceptual Constancy Perceiving stimuli consistently across various conditions Allows to Flexibility navigate our world as conditions change Maintain object recognition Includes shape size and color Shape constancy still recognize the object even if shape changes e g due to perspective Size constancy perceive objects as same size as matter their distance Expanding shrinking tells us that distance is changing Color constancy ability to perceive color consistently across different illumination 10 From the textbook What does gestalt refer to Know and be able to give examples of the six gestalt principles that your book discusses proximity similarity continuity closure symmetry figure ground Gestalt whole We perceive objects as wholes within their overall context 11 What is depth perception Why is it necessary Depth Perception the visual ability to see the world in 3D 12 Be able to define and give an example of each of the seven monocular cues discussed in class motion parallax interposition relative size height in plane familiar size aerial perspective texture gradient and linear perspective Motion parallax Info about a scene at two different time points Interposition when one objects abstracts part of another object we can tell the relative order of the two objects Molecular cues aerial perspective texture gradient light is scattered by the atmosphere Thus objects in distances appear hazier and less distinct Linear Perspective parallel lines appear to converge giving us a sense of distance 13 Be able to define the two binocular cues discussed in class What is stereopsis Convergence Divergence Eyes turn in to focus on an object that s closer Eyes turn out to focus on an objects that is father Binocular disparity differences between the two retinal images of the same scene Stereopsis Binocular perception of depth what allows us to actually see in 3D 14 How does our brain perceive motion The brain perceives motion by comparing visual frames Rapid series of slightly varying images creates perception of motion 15 What are two ways in which we selectively attend to our environment discussed in class Why is this selective attention generally beneficial We attend selectively to our environment 1 Sensory Adaptation when first detected when decreases 2 Inattentional Blindness failure to detect stimuli in activation of sense receptors is greatest 16 What is change blindness How does it work What are the two types of disruptions that can cause change blindness Why does change blindness occur and how does it relate to the way our brain perceives motion How is change blindness related to attention Change Blindness Inability to detect changes in an object or scene Can make significant changes without people immediately noticing How it works momentary disruption between the original scene and the changed scene Global disruption total obscuring of object scene between changes Partial disruption small disturbances which draw attention Ex Flicker technique Ex mud splash Under normal conditions change is detected by local motion signals Why does it work Disruptions overload these signals The brain has to attend to each item in the scene to detect whether or not a change in scene has occurred
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