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SENSATION AND PERCEPTION
6-8% of the AP Psychology Exam
TWO STORIES ABOUT DOGS…
SENSATION AND PERCEPTION
Sensation- process by which sensory receptors receive energy from the external environment and transform it into neural energy
Perception- the process of organizing and interpreting sensory information
PROCESSING
Bottom-up processing Begins with sensation and works up to the brain The type of processing used when we have no prior knowledge
Top-down processing Begins with cognition We construct perceptions drawing on experience and expectation
Uses prior knowledge
SENSORY RECEPTION
Signal
• External stimuli picked up by sensory receptors
• Photoreceptors• Mechanoreceptors• Chemoreceptors
Transduction
• Energy is transformed into action potential
• Strength of the stimulus is represented by the frequency of action potentials
Response
• The brain processes information (perception)
• Signals the body to respond if necessary
THRESHOLDS- RECEIVING A SENSATION
Absolute threshold- the minimum amount of stimulus energy that a person can detect
Difference threshold- the degree of difference that must exist between two stimuli before a difference can be detected
Weber’s Law: difference threshold must differ by a constant minimum percentage rather than a minimum amount
PERCEPTION
Subliminal Perception- The detection of information below the level of conscious awareness Example: thirsty words study
Signal Detection Theory- Theory of perception that focuses on decision making (top-down processing) about stimuli in the presence of uncertainty
SENSATION VS. PERCEPTIONWHAT DO YOU SEE?
SELECTIVE ATTENTION
Selective Attention- the focusing of conscious awareness on a particular stimulus
Cocktail Party Effect- being able to focus on one conversation, or one voice, in a room full of people
FAILURES OF SELECTIVE ATTENTION
Inattentional Blindness:
failing to see visible objects when our attention is focused elsewhere
Closely related to change blindness- the inability to notice change when not focused on a specific aspect of a scene
SELECTIVE ATTENTION
SELECTIVE ATTENTION
FAILURES OF SELECTIVE ATTENTION
Google: “The Stroop Effect Online” – First Link
The Stroop Effect: represents failure of selective attention
Pop-Out Phenomena: powerful or strikingly distinct stimuli that cannot be ignored
FAILURES OF SELECTIVE ATTENTION
Page 107 in your book.
Perceptual Set: a predisposition or readiness to perceive something in a particular way; a result of top-down processing
SENSORY ADAPTATION
A change in the responsiveness due to constant exposure to a stimulus
EXTRASENSORY PERCEPTION (ESP)
Known in the psychology community as parapsychology
It is NOT real
Science depends on three things: evidence, valid conclusions, reproducibility
While it has been studied over the past 75 years, no scientific evidence supports the existence of ESP