SENSATION AND
PERCEPTION
SENSATION AND PERCEPTION
• Sensation: the stimulation of sense organs---absorption of
energy (light/sound waves)
• Perception: selection, organization, and interpretation of
sensory input---organizing and translating absorbed energy
PSYCHOPHYSICS: BASIC
CONCEPTS AND ISSUES
• Def: study of how physical stimuli are translated into
psychological experience
• Gustav Fechner: published idea in 1860; laid the groundwork
for Wundt
THRESHOLDS: LOOKING FOR
LIMITS
• Def: a dividing pt. btwn energy levels that do and do not have
a detectable affect
• What is the weakest detectable stimulus for any given sense?
ABSOLUTE THRESHOLD
• Def: the minimum amount of stimulation that an organism can
detect
• Define boundaries of sensory capabilities
• Not really absolute
JUST NOTICEABLE
DIFFERENCE
• Def: the smallest difference in the amount of stimulation that
a specific sense can detect
• Greater for heavier objects
• Weber’s Law: the size of a JND is a constant proportion
(Weber’s fraction) of the size of the initial stimulus
PSYCHOPHYSICAL SCALING
• Fechner’s Law: the magnitude of a sensory experience is
proportional to the # of JNDs that the stimulus causing the
experience is above absolute threshold
SIGNAL DETECTION THEORY
• The detection of stimuli involves decision processes, which are
both influenced by a variety of factors besides stimulus
intensity
• Hits, misses, false alarms, correct rejections
• Depend on criterion and “noise”
PERCEPTION WITHOUT
AWARENESS
• Subliminal Perception: registration of sensory input w/o
conscious awareness
• James Vicary
• Produces weak effects
SENSORY ADAPTATION
• Def: a gradual decline in sensitivity to prolonged stimulation
• Automatic
• Tunes in to changes, not constants