Chapter 4 Sensation and Perception Sensation vs Perception Sensation Basic processes by which sensory receptors and the nervous system Receive and represent stimulus energies from environment and entails basic psychological experiences Bottom Up Processing Sensory detection and encoding construction of whole from parts This includes Lines shapes angels colors items events that grab our attention Perception Interpretation and integration Top Down processing conceptually driven organization interpretation of info Experiences Expectations Absolute vs Difference Thresholds Absolute threshold Minimum stimulation needed to detect a particular stimulus 50 of the time 1 Smallest detectable level of a stimulus Difference Thresholds Minimum difference between two stimuli required for detection 50 of the time The measure of how different two stimuli have to be in order for 2 the subject to notice that they are not the same II Signal to noise Ratio Signal detection Theory Signal detection theory Predicts how and when we detect A presence of a faint stimulus signal among background noise Signal to noise ratio It becomes harder to detect a signal as B background noise increases This depends on 1 2 3 Experience Expectations Motivation 4 Level of fatigue III Sensory Adaptation A B Activation is greatest when a stimulus is first detected Sensitivity diminishes as a consequence of constant stimulation 1 my socks are on my socks are on IV Sensory interactions The principle that one sensory system may affect another cross modal processing 1 Ex Smell of food influences taste When Visual information influences auditory perception 2 McGurk effect McGurk effect Demonstrates that we integrate visual and B auditory information when processing spoken language and our brains automatically calculate the most probable sound given the info from the two sources 1 Saying ba seeing ga V Parallel Processing A simultaneously Parallel Processing The ability to attend to many sense modalities 1 Bottom up processing Construct a whole stimulus from its parts a Perceptual Constancy Top Down processing Starts with beliefs and expectations 2 which we then impose on the raw stimuli we perceive a Perceptual set B Comes into play with ink blots VI Blindsight and Visual System Inattentional Blindness Failure to detect stimuli that are in plain A sight when our attention is focused elsewhere Selective attention Process of selecting one sensory channel and B ignoring or minimizing others VII Subliminal stimuli There is compelling evidence both ways that subliminal stimuli A may have some influence and the opposite VIII How we pinpoint sounds A tone with a specific pitch B reproduces the pitch Place theory Specific place along the basilar membrane matches a Frequency theory rate at which neurons fire the action potential C We rely most on binaural cues to detect the source of sounds IX Pain Gate control model Idea that pain is blocked or gated from A consciousness by neural mechanisms in spinal cord B C D Phantom pain pain or discomfort in the missing limb Benefit of pain protects our bodies Things that may affect someone s perception of pain 1 2 Culture Mind over matter X Perceptual Set A perceptions Perceptual set set formed when expectations influence B We may expect to see either a woman or old lady then see it XI Perceptual constancies Perceptual constancies the process by which we perceive stimuli A consistently across varied conditions Without this we d be constantly confused because we d be B seeing our worlds as continually changing C Brain allows us to fix minor changes Several types include shape constancy size constancy color D constancy etc XII Gestalt Gestalt principles Rules governing how we perceive objects as A wholes within their overall context They help explain why we se much of our world as consisting of unified figures rather than lines and curves XIII Perception of motion The brain judges how things in our world are constantly changing A by comparing visual frames like those in a movie Phi phenomenon illusory perception of movement produced by B the successive flashing of images XIV Illusions A we do Illusions help us understand why we perceive the world the way
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