Sensation and PerceptionSlide 2SensationPsychophysicsJust Noticeable DifferencePerceptionPerceptual HypothesesSlide 8AttentionSlide 10Subliminal Information ProcessingSubliminal PersuasionExtrasensory Perception (ESP)Scientific Evidence for ESPSlide 15PsychicsSensation Sensation and and Perception Perception Chapter 4Chapter 4Sensation and Perception Sensation and Perception •Sensation:Sensation: refers to the detection of physical refers to the detection of physical energy by our sense organsenergy by our sense organs•Perception:Perception: the brain’s interpretation of these raw the brain’s interpretation of these raw sensory inputssensory inputs•Sensation is your window to the worldSensation is your window to the world•Perception Perception is interpreting what comes in your is interpreting what comes in your windowwindowSensationSensation•First step in sensation is First step in sensation is transductiontransduction–Process by which the nervous system converts an Process by which the nervous system converts an external stimulus into electrical signals within neuronsexternal stimulus into electrical signals within neurons•A specific type of A specific type of sense receptorsense receptor transduces a transduces a specific stimulusspecific stimulus•Sensory adaptationSensory adaptation–Activation is greatest when a stimulus is first detectedActivation is greatest when a stimulus is first detectedPsychophysicsPsychophysics•The study of how we perceive sensory stimuli The study of how we perceive sensory stimuli based on their physical characteristicsbased on their physical characteristics•Absolute thresholdAbsolute threshold–The lowest level of a stimulus we can detect on 50 The lowest level of a stimulus we can detect on 50 percent of the trials when no other stimuli of that type percent of the trials when no other stimuli of that type are present.are present.–Demonstrates how remarkably sensitive our sensory Demonstrates how remarkably sensitive our sensory systems aresystems areJust Noticeable DifferenceJust Noticeable Difference•The smallest change in the intensity of a stimulus The smallest change in the intensity of a stimulus that we can detectthat we can detect•Relevant to our ability to distinguish a stronger Relevant to our ability to distinguish a stronger from a weaker stimulusfrom a weaker stimulus•Weber’s LawWeber’s Law–There is a constant proportional relationship between There is a constant proportional relationship between the JND and original stimulus intensitythe JND and original stimulus intensity–In other words, the stronger the stimulus, the bigger the In other words, the stronger the stimulus, the bigger the change needed for a change in stimulus intensity to be change needed for a change in stimulus intensity to be noticeablenoticeablePerceptionPerception•Parallel ProcessingParallel Processing–Our brains can attend to many sense modalities Our brains can attend to many sense modalities simultaneouslysimultaneously•Bottom-up ProcessingBottom-up Processing– When we construct a whole stimulus from its partsWhen we construct a whole stimulus from its parts•Top-down ProcessingTop-down Processing–Starts with our beliefs and expectations which we Starts with our beliefs and expectations which we impose on the raw stimuli we perceiveimpose on the raw stimuli we perceivePerceptual HypothesesPerceptual Hypotheses•Our brains try to get by conserving as much Our brains try to get by conserving as much neural firepower as possible neural firepower as possible  cognitive misers cognitive misers •Perceptual SetsPerceptual Sets– Occurs when our expectations influence our perceptionsOccurs when our expectations influence our perceptions–Young woman or old witch?Young woman or old witch?Perceptual HypothesesPerceptual Hypotheses•Perceptual ConstancyPerceptual Constancy–Process by which we perceive stimuli consistently across Process by which we perceive stimuli consistently across varied conditionsvaried conditions–Shape constancyShape constancy–Size constancySize constancy–Color constancyColor constancyAttentionAttention•Selective AttentionSelective Attention–Process of selecting one sensory channel and ignoring or Process of selecting one sensory channel and ignoring or minimizing othersminimizing others•Broadbent’s filter theory of attentionBroadbent’s filter theory of attention–Mental filter enables us to pay attention to important Mental filter enables us to pay attention to important stimuli and ignore othersstimuli and ignore others–Dichotic listeningDichotic listening•Cocktail-party effectsCocktail-party effects–Refers to our ability to pick out an important message in a Refers to our ability to pick out an important message in a conversation that does not involve usconversation that does not involve usAttentionAttention•Inattentional BlindnessInattentional Blindness–We are bad at detecting stimuli in plain sight when our We are bad at detecting stimuli in plain sight when our attention is focused elsewhereattention is focused elsewhere–Passing a basketball missing the gorilla walked throughPassing a basketball missing the gorilla walked through•Change BlindnessChange Blindness–Closely related to inattentional blindnessClosely related to inattentional blindness–Failure to detect obvious changes in one environmentFailure to detect obvious changes in one environmentSubliminal Information Subliminal Information ProcessingProcessing•We process many of the sensory inputs to which We process many of the sensory inputs to which we are exposed unconsciouslywe are exposed unconsciously•Many of our actions occur with little or no Many of our actions occur with little or no forethought or deliberationforethought or deliberation•Subliminal Perception:Subliminal Perception: processing of sensory processing of sensory information below the threshold of conscious information below the threshold of conscious awarenessawareness–Evidence that this occursEvidence that this occursSubliminal PersuasionSubliminal Persuasion•Different from subliminal perceptionDifferent from subliminal perception•Subthreshold influences over our votes in Subthreshold influences over our votes in elections, product choices, and life decisionselections, product choices, and life decisions•Highly unlikely because we cannot engage in Highly unlikely because we cannot engage in