 Sensation
= stimulation of sense organs.
 Perception
= selection, organization, and
interpretation of sensory input

Light travels in waves with two important
properties
• Wavelength - perceived as color
• Amplitude - perceived as brightness
 Purity
= how varied mix of wavelengths; influences
perception of the saturation, or richness, of colors
 Eyes
serve 2 main purposes:
• channels light to neural tissue that receives it, called
the retina,
• houses that tissue.
 Retina
= neural tissue in eye that absorbs
light, processes images, & sends visual
signals to the brain.


Rods – for viewing dim light with no color
Cones – for bright light with color
 Involves
changes in retina’s sensitivity to
light.
• dark adaptation - eyes become more sensitive to
light in low illumination
• light adaptation- eyes become less sensitive to light
in high illumination.
 Collection
of rod & cone receptors that
funnel signals to particular visual cell in
retina, make up that cell’s receptive field.
 Receptive
fields - areas in retina that affect
firing of visual cells.
 After
processing in primary visual cortex,
visual information is shuttled along the what
and where pathways to other cortical areas.
 The
dorsal stream, or where pathway,
processes information about motion & depth,
moves on to areas of the parietal lobe.
 The
ventral stream, or what pathway,
processes info about color & form, moves on
to areas of the temporal lobe.
• has neurons inside that are especially sensitive to
faces.
 Research
suggests visual cortex contains
cells that function as feature detectors.
• feature detectors = neurons that respond selectively
to very specific features of more complex stimuli.
 Subtractive
color mixing = removing some
wavelengths of light, leaving less light than
was originally there.
• E.g. yellow – red = green
 Additive
color mixing = superimposing lights,
putting more light in the mixture than exists
in any one light by itself.
• E.g. shining a red, green & blue spotlight on white
surface.

Perception of color
is based on the
response rates of
three kinds of
cones

Proposes the existence of “opposing” redgreen, blue-yellow, and black-white channels
 Perception
of color appears to involve stages
of information processing
• Receptors that do first stage of processing (cones)
seem to follow the principles outlined in trichromatic
theory.
• Later stages of processing seem to follow the
principles outlined in opponent process theory.
 Perceptual
set—a readiness to perceive a
stimulus in a particular way.
• creates a certain slant in how you interpret sensory
input.
 Inattentional
blindness = failure to see fully
visible objects or events in a visual display
because one’s attention is focused
elsewhere.
 Figure
- object being looked at
 Ground
- background against which it stands.
 Feature
analysis = detecting specific
elements in visual input & assembling them
into a more complex form.
 Gestalt
psychology basic assumption - that
the whole can be greater than the sum of its
parts.
 Proximity
= Things that are near one another
seem to belong together.
 Similarity
= group stimuli that are similar.
 Simplicity
= Pragnanz, (German as “good
form); people tend to organize forms in the
simplest way possible.
 Continuity
= reflects people’s tendency to
follow in whatever direction they’ve been led.

Source : Microsoft ClipArt
 Gestalt
principles of proximity, similarity,
continuity, closure, & simplicity, explain how
we group elements into higher-order forms.
 Perceptual
hypothesis = inference about
what form could be responsible for a pattern
of sensory stimulation.
 Depth
perception = interpretation of visual
cues that indicate how near or far away
objects are.

Source: Microsoft ClipArt
 Binocular
depth cues = clues about distance
based on differing views of two eyes.
 Retinal
disparity = objects within 25 feet project
images to slightly different locations on right &
left retinas, so right & left eyes see slightly
different views of object.

Source: Microsoft ClipArt
 Monocular
depth cues =
clues about distance
based on image in
either eye alone.
 Depth
perception
depends primarily on
monocular cues
2
kinds of monocular cues to depth:
• Active use of the eye in viewing the world.
• Pictorial depth cues—cues about distance that can
be given in a flat picture.
 People
from pictureless societies have some
difficulty in applying pictorial depth cues to
two-dimensional pictures.
 Visual
illusion = inexplicable discrepancy
between the appearance of a visual stimulus
and its physical reality.
Hearing
 Sound
waves = vibrations of molecules,
which means that they must travel through
some physical medium, such as air.

Characterized by wavelength (frequency), amplitude,
and purity

Wavelength = perceptions of pitch

Amplitude = perceptions of loudness

Purity = key determinant of timbre.
 Wavelengths
are described in terms of their
frequency, which is measured in cycles per
second, or hertz (Hz).
 Humans
can hear frequency ranging from 20
Hz up to 20,000 Hz .
 The
greater the amplitude of sound waves,
the louder the sound perceived.
• measured in decibels (dB).
• loudness ultimately depends on an interaction
between amplitude and frequency.
 External
 Middle
 Inner
ear = vibration of air molecules.
ear = vibration of movable bones.
= waves in a fluid,
 which
are finally converted into a stream of
neural signals sent to the brain ( Moore,
2001).
 external
ear consists mainly of the pinna, a
sound-collecting cone.
 Sound
waves funneled along the auditory
canal toward the eardrum, a taut membrane
that vibrates in response.
 Vibrations
of eardrum are transmitted inward
by a mechanical chain made up of the three
tiniest bones in your body (the hammer,
anvil, and stirrup), known collectively as the
ossicles.
 Inner
ear consists largely of the cochlea, a
fluid-filled, coiled tunnel that contains the
receptors for hearing.
 Basilar
membrane = runs length of the
spiraled cochlea, holds the auditory
receptors, called hair cells.
Taste, Smell, and Touch
 Gustatory
receptors = clusters
of taste cells found in taste
buds that line trenches
around tiny bumps on the
tongue.
 The
taste buds are sensitive to five basic
tastes: sweet, sour, bitter, salty & umami
(savory)
 Taste
signals are routed through thalamus
and sent on to insular cortex in frontal lobe.
 Supertasters
= more sensitive to some tastes
than nontasters, with medium tasters falling in
between.
 Nontasters
= more susceptible to lure of
sweets, high-fat foods, alcohol, & smoking, tend
to be less healthy than those of supertasters.
 sensory
adaptation—gradual decline in
sensitivity to prolonged stimulation
 Physical
stimuli = chemical substances—
volatile ones that can evaporate and be
carried in the air.
 These
chemical stimuli are dissolved in
fluid—mucus in nose.
 The
receptors for smell are olfactory cilia,
hairlike structures located in the upper
portion of the nasal passages ( Getchell &
Getchell, 1991).
 Skin
houses many types of sensory
receptors.
• Responds to pressure, temperature, & pain.
 Pain
signals are sent to brain along two
pathways that are characterized as fast and
slow.
 Perception
of pain is highly subjective and
may be influenced by culture, mood, and
contextual factors.
 Gate-control
theory holds that incoming pain
sensations must pass through a “gate” in the
spinal cord that can be closed, thus blocking
ascending pain signals.
 Endorphins
& a descending neural pathway
appear responsible for this suppression of
pain.

Source: Miscrosoft ClipArt