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. PERCEPTION WHAT 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

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