Chapter 6: Sensation &
Perception
Section 1: Our Sensational
Senses
• PDN:
Read Psychology in the News
• Pages 174-175
Sensation and Perception
• Sensation: The detection of physical
energy emitted or reflected by physical
objects
–it occurs when energy in the external
environment or the body stimulates
receptors in the sense organs.
–Produce an immediate awareness of
sound, color, form, etc
• Perception: The process by which the
brain organizes & interprets sensory
information.
• Foundation of learning, thinking, &
acting
• An understanding can help us think
more critically about our own
experiences
Ambiguous Figure
• Colored surface can be
either the outside front
surface or the inside
back surface
–Cannot simultaneously
be both
• Brain can interpret the
ambiguous cues two
different ways
Our Sensational Senses
• Skin- touch, pressure, hot,
cold, pain, itching, & tickling
• Ears- hearing & sense of
balance
Measuring the Senses
• Absolute Threshold
–The smallest quantity of
physical energy that can be
reliably detected by an observer
• Difference Threshold
–The smallest difference in
stimulation that can be reliably
detected by an observer when two
stimuli are compared
• also called Just Noticeable
Difference (JND).
Absolute Sensory Thresholds
• Vision: A single candle flame from 30 miles
on a dark, clear night
• Hearing: The tick of a watch from 20 feet in
total quiet (measured in decibels)
• Smell: 1 drop of perfume in a 3-room
apartment
• Touch: The wing of a bee on your cheek,
dropped from 1 cm
• Taste: 1 tsp. Sugar in 2 gal. water
• Despite our impressive sensory skills,
our senses are tuned to a narrow
band of physical energies.
• Other species can detect signals that
we cannot.
Signal Detection Theory
• Holds that responses in a detection
task depend on a sensory process &
a decision process.
• These may vary with a person’s
motivation, alertness, & expectations
Sensory Adaptations
• Senses are designed to respond to
change & contrast in the environment
• Sensory Adaptation: The reduction or
disappearance of sensory
responsiveness that occurs when
stimulation is unchanging or
repetitious.
• Picture page 179
• Useful because it spares us from
having to respond to unimportant
information
–Rarely adapt completely to
visual stimuli
• Sensory Deprivation: The
absence of normal levels of
sensory stimulation.
Sensory Overload
• Can lead to fatigue & mental
confusion
• “Cocktail Party Phenomenon”
–A person typically focuses on
just one conversation, ignoring
other voices, music, laughter,
etc
• Selective Attention: The focusing
of attention on selected aspects
of the environment and the
blocking out of others.