sensation & perception attention, processing, thresholds
Post on 18-Jan-2016
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Sensation & Perception
ATTENTION, PROCESSING, THRESHOLDS
• Goals Contrast sensation & perception; understand how we process & attend to stimuli in the environment.
Sensation
• Process by which our sensory receptors and nervous system receive and represent stimulus energy
Perception• Process of organizing & interpreting
sensory information, enabling us to recognize meaningful objects and events
Bottom-up Processing• Analyze stimulus beginning w/sensory
receptors and work up to brain’s integration of sensory info
Sensory cortex
Auditory cortex
Top-down Processing• Process info by higher-level mental
processes• Draw upon experiences &
expectations
Selective Attention: Focusing conscious awareness• “Cocktail party affect” – attending to
one sound/voice in an environment • Inattentional blindness – missing stimuli
in environment due to selective attention
• Change blindness – missing changes in stimuli due to selective attention
• Goal Distinguish between absolute thresholds and difference thresholds.
What is the absolute threshold?• Weakest amount of a stimulus
that a person can detect 50% of the time
Signal Detection Theory • Predicts how and when we detect the
presence of a faint stimulus (signal) amid background stimulation (noise)
Assumes that there is no single absolute threshold
Detection depends partly on person’s experience expectations motivation level of fatigue
Subliminal Perception• Below one’s absolute threshold for
conscious awareness• Priming will activate
your conscious mind, predisposing one’s perception, memory, or response
0
25
50
75
100
LowAbsolutethreshold
Medium
Intensity of stimulus
Percentageof correctdetections
Subliminal stimuli
What is the difference threshold?• Minimal difference or change in
intensity of a stimulus that a person can notice 50% of the time– i.e. Change in volume on the radio,
change in lighting
Sensory Adaptation• Decreased sensation
due to constant stimulation.
• Decreased sensitivity to stimulus
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