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