10 16 2013 Jaclyn Spielsinger Psych Chapter 6 Principles of Perception Sensation v Perception Bottom up vs Top down processing o Sensation occurs when some event whether it is a sound a light or a touch is detected by receptors in your body and an impulse is sent to the brain o Perception occurs when the brain receives the sensory information coming in from the body organizes it and interprets it When you look at the image to the right you eye senses all sorts of individual lines and shapes depicted in red above it but your brain integrates all of the shapes and their locations and perceives a chair o Bottom up processing refers to perception that is pieced together as sensory information coming in If I flash a random picture on the screen your eyes detect the features your brain pieces it together and you perceive a picture of an eagle What you see is based only on the sensory information coming in Bottom up refers to the way it is built up from the smallest pieces of sensory information o Top down processing on the other hand refers to perception that is driven by cognition Your brain applies what it knows and what it expects to perceive and fills in the blanks so to speak Surrounded by sequential letters your brain expects the shape to be a letter and to complete the sequence In that context you perceive the lines to form the shape of the letter B Surrounded by numbers the same shape now looks like the number 13 When given a context your perception is driven by your cognitive expectations Now you are processing the shape in a top down fashion Phonemic Restoration perceptual phenomenon where under certain conditions sounds actually missing from a speech signal can be hallucinated by the brain and clearly heard Gestalt Principles of Perception o German for whole or form o Refers to idea that what we perceive from top down processing has more meaning than what would be perceived from simply bottom up processing Figure Ground used to describe the tendency of the visual system to simplify a scene into the main object that we are looking at the figure and everything else that forms the background or ground Proximity principle of proximity or contiguity states that things which are closer together will be seen as belonging together Similarity states that things which share visual characteristics such as shape size color texture value or orientation will be seen as belonging together Good continuation principle of continuity predicts the preference for continuous figures We perceive the figure as two crossed lines instead of 4 lines meeting at the center Closure related to principle of good continuation there is a tendency to close simple figures independent of continuity or similarity This results in a effect of filling in missing information or organizing information which is present to make a whole Area principle of area states that the smaller of two overlapping figures is perceived as figure while the larger is regarded as ground Symmetry principle of the symmetrical figure is that it is seen as a closed figure Symmetrical contours thus define a figure and isolate it o Cornea admits light to the interior of the eye and bends the light rays to that they can be brought to a focus o Iris choroid coat forms the iris in the front of the eye o Lens located just behind the iris and is held in position by zonules extending from an encircling ring of muscle o Pupil the size of its opening o Aqueos humor front chamber is filled with a watery liquid o Ciliary muscle thickened portion of the vascular tunic of the eye located between the choroid and the iris o Vitresous body rear chamber is filled with a jellylike material o Retina inner layer of the eye o Fovea center most part This tiny area is responsible for our central sharpest vision from its ground Vision o Blind spot the point on the retina where the approximately 1 million axons converge on the optic nerve there are no rods or cones o Optic nerve nerve that transmits visual information from the retina to the brain o Cones color o o Rods black and white o number of different visual cues that help us perceive depth and Depth Perception motion eye o Monocular Cues allow us and other animals to perceive depth using only one Interposition if one object partially blocks the view of another we Relative height objects higher in our field of vision are perceived as farther away causes the illusion that taller objects are longer than perceive it as closer shorter objects Familiar Relative size if we assume two objects are similar in size we perceive the one that casts the smaller retinal image as farther away Texture gradient a gradual change from course distinct texture to fine indistinct textures signals increasing distance Shadow nearby objects reflect more light to our eyes dimmer objects seem farther away assuming light comes from above Linear perspective parallel lines such as RR tracks seem to converge with distance the greater the convergence the greater the distance perceived Motion parallax as we move objects that are closer to us move farther across our field of view than do objects that are in the distance Accommodation eye s ability to change its focus from distant objects to near objects o Binocular Cues Retinal disparity By comparing images from the two eyeballs the brain computes distance the greater the disparity difference between the two images the closer the object The Ear o Outer ear Binocular disparity 3D movies This picture shows how binocular disparity has often been used in comic books magazines and movies The picture contains two images of a chair one red and one blue from two slightly different angles You can see the image by putting on special 3D glasses One lens of the glasses will filter out the blue image and the other lens will filter out the red image The result is each of your eyes only receiving one of the two images on the page Just as if you were looking at a real chair from two different angles your brain forms these images into one three dimensional image Pinna acts like a funnel to collect the sound wave Auditory canal Sound waves pass through canal Tympanic membrane known as the eardrum is a thin membrane that separates the external ear from the middle ear Its function is to transmit sound from the air to the ossicles inside the middle ear o Middle ear 3 bones called ossicles Malleus hammer shaped primary function of the malleus is the transmission of sound waves or vibrations from the eardrum to the
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