Chapter 3 study guide - Chapter 3 Sensation Perception J...

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Chapter 3: Sensation & Perception We understand world thru our senses, our “windows” on the world Our reality= dependent upon 2 basic processes: o Sensation : gathering info & recording by sensory structures ; mechanical process o Perception : interpreting info; interpretation of sensory info by the brain ; active process Perception does not offer an exact replica of the world outside brain subjectively constructs the world using innate & learned assumptions & principles Detection Question : concerned w/ the limits on our ability to detect very faint signals How intense does a light have to be for us to see it? How intense does a sound have to be for us to hear it? o Absolute threshold : minimum amt of energy in a sensory stimulus that’s detected 50% of the time o Subliminal stimulus : stimulus that’s detected only up to 49% of the time Any effects of subliminal persuasion = short-lived w/ no long-term consequences on our behavior o Signal detection theory : detection of faint sensory stimuli depends upon person’s physiological sensitivity to a stimulus AND upon decision criterion for detection, which is based on nonsensory factors Difference Question : concerned w/ limits on our detection abilities; our ability to detect very small differences b/w stimuli What is the smallest difference in brightness b/w two lights that we can see? What is the smallest difference in loudness b/w two sounds that we can hear? o difference threshold ( just noticeable difference ( jnd )): minimum difference b/w 2 stimuli that’s detected 50% of the time o Weber’s Law: for each type of sensory judgment, the difference threshold = a constant fraction of the standard stimulus value used to measure it Scaling Question : concerned w/ how we perceive magnitudes (intensities) of clearly detectable stimuli What is the relationship b/w the actual physical intensities of stimuli & our psychological perceptions of these intensities? o Steven’s Power Law : perceived magnitude of a stimulus = equal to its actual physical intensity raised to a constant power for each type of judgment to perceive a light as twice as bright, its actual intensity has to be increased between and 8 and 9 times if an electric shock is doubled in intensity, we perceive it as being about 10 times more intense o Sensory adaptation : disappearance to repetitive or unchanging stimuli Survival value—its more imp to detect new stimuli (can signal danger) than constant stimuli Hue : color experienced Wavelength: distance in 1 cycle of a wave, from 1 crest to next o human can see wavelengths of ~400- 700 nanometers Amplitude : amt of energy in a wave (its intensity) which is the height of wave @ its crest; determines its brightness o small amplitude= soft sounds: dull colors o great amplitude= loud sounds ; bright colors o sound waves loudness= amplitude expressed in decibels ( dB ) frequency

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