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SlideShare utilise les cookies pour améliorer les fonctionnalités et les performances, et également pour vous montrer des publicités pertinentes. Si vous continuez à naviguer sur ce site, vous acceptez l’utilisation de cookies. Consultez notre Politique de confidentialité et nos Conditions d’utilisation pour en savoir plus.
the process of receiving
stimulus energies from the
eyes (visual system)
the process of
physical energy into
the process of
Processing that begins with sensory
receptors registering environmental
information and sending it to the brain
for cognitive processing and integration.
Processing of perpetual information that
starts out with cognitive processing at the
higher levels of the brain.
Why is it important to study sensation
The purpose of perception is:
1) to represent information from the outside
2) adaptation that improves a species’ chances
for survival; and
3) to help in designing devices to restore
perception to those who have lost some (or
all) and also to devise treatments for other
All sensation begins with sensory receptors.
Sensory receptors are specialized cells that
detect and transmit stimulus information to
sensory nerves and the brain.
3 Classes of SENSORY RECEPTORS
1.Photo reception(detection of
light, perceived as sight.)
2.Mechanoreception (detection of
pressure, vibration, and
movement perceived as touch,
hearing and equilibrium.)
Chemoreception (detection of
chemical stimuli detected as smell
How close does an
approaching bumblebee have
to be before you can here its
Difference between a ‘Coke’
and a ‘Coke Zero’?
The percentage of fat in a ‘low
fat’ and a regular milk?
A level or point at
starts or ceases to
happen or come in
-Watching TV while your roommate
Minimum amount of energy that a person
just noticeable difference (jnd)
the degree of difference that must exist
between two stimuli before the difference
Percent of yes responses
Distance in feet from an alarm clock.
Approximate Absolute Thresholds
A candle flame at 30 miles on a dark, clear night.
A ticking watch at 20 feet under quiet conditions.
One drop of perfume diffused throughout 3 rooms
A teaspoon of sugar in 2 gallons of water
The wing of a fly falling on your cheek from a distance
of one centimeter.
Watching TV while your
roommate is sleeping.
Your roommate, suddenly
Also wants to watch the
A student late for his class.
10: 03 – late?
10:05 – late?
10: 10 – late?
10:15 – late!!!
It takes 15 minutes for a student to
be detected as late.
Absolute or difference threshold?
*Depends on the individual who
perceives and the condition of the
The principle that two
stimuli must differ by a
percentage to be
perceived as different.
-the ability to detect
information below the
level of conscious
SIGNAL DETECTION THEORY
The theory that focuses on
decision making about
stimuli in the presence of
depends on a variety of
factors beside the physical
intensity of the stimulus and
the sensory abilities of the
PERCEIVING SENSORY STIMULI
focusing on a specific
aspect of experience while
B. Perceptual Set
a predisposition, or
readiness, to perceive something
in a particular way.
A change in the
responsiveness of the sensory
system based on the average level
of surrounding stimulation.
CHARACTERISTICS of LIGHT
1.Wavelength- distance from
LIGHT of one wave to the
next. of electromagnetic
2. energy that can be
3. described in terms of a
Amplitude- the height of
4.Purity- the mixture of
through space in waves.
wavelengths in light.
PARTS OF THE EYE
the white outer part
of the eye that helps
maintain the shape
and protects from
the colored part of the
eye, contains muscle
that control the size of
the pupil, hence, the
amount of light that
appears black, and
is the opening in
the center of the
The light sensitive surface
in the back of the eye that
houses light receptors.
A transparent, flexible, disklike
gelatinous material. Use to bend
light on the eye.
A minute area in the center of the retina which
vision is at its best.
It’s the place on the retina
where the optic nerve leaves
the on its way to the brain.
A clear membrane just in front of the eye.
located in the occipital lobe of
the brain. Visual information
processing involves feature
detection, parallel processing
(David Hubel&Torsten Wiesel)
neurons of the brain’s visual
system that respond to particular
lines or other features of a
processes information about
what the object is, its color, form
and its texture; temporal lobe.
processes information on an
object’s location, movement, depth
of the object; parietal lobe.
The bringing together
and integration of
what is processed by
(THOMAS YOUNG 1802)
(ex: HERMANN von HELMONTZ 1852)
Color perception is based
on the existence of three
of color receptors that are
maximally sensitive to
different, but overlapping
Color perception is based on
the existence of three color
receptors that are maximally
sensitive to different, but
overlapping, ranges of
people with only two kinds of cones.
have three kinds of cone receptors and
C.Afterimages- sensations that remain after a
stimulus is removed.
Cells in the visual sys. respond to green and
blue-yellow colors; a given cell might be
excited be red and inhibited by
green, whereas another might be excited by
yellow and inhibited by blue.
The sensory receptor cells become less
responsive to an unchanging stimulus.
The receptors are no longer sending signals to
- The sensory receptor cells are still responding to
the stimulus, but the lower centers of the brain
are not sending the signals from those
receptors in the cortex.