Sensation and Perception
Course Instructor: Qubsha Munir
Sensing the word around us
o Sensory systems → Sense organs having 5 major senses
o What are your senses?
1. Hearing
2. Vision
3. Taste
4. Touch
5. Smell
Sensation
o The passive process of bringing information from the outside world into the body and
to the brain.
o Sensation occurs when special receptors in the sense organs- the eyes, ears, nose, skin
and taste buds are activated allowing various forms of outside stimuli to become neural
signal in the brain.
Smell /olfactory
Seeing/ visual/optical
Hearing/auditory
Taste/gustatory
Touch/tactile
Senses Distinguishing ability.
Sensation happens when
you feel wind on your
face.
Feeling Pulse
Sensation happens
when you eat noodles.
When you hear a car horn
honking in the distance.
Sensation and Perception
Sensation refers to the initial detection of energy from the physical
world
Perception, on the other hand, the sorting out, interpretation, analysis,
and integration of stimuli by the sense organs and brain.
Stimulus is any passing source of physical energy that produces a
response in a sense organ.
Perception
oPerception is the active process of selecting, organizing
and interpreting the information brought to the brain by
the senses.
oThe perceptual process is a sequence of steps that begins
with the environment and leads to our perception of
stimulus and action in response to the stimulus.
oPerception has some individuality to it, no two people will
perceive the world in exactly same way. Two individuals
might be looking at the clouds, for example while one think
its shaped like a horse, the other think its more like a cow.
They both see same cloud, but they perceive a different
interpretation.
Difference between Sensation
b/w Perception
Absolute Threshold
o Absolute threshold is the smallest level of stimulus that can be detected.
o In hearing, the absolute threshold refers to the smallest level of a tone that
can be detected by normal hearing when there are no other interfering sounds
present.
o In vision, the absolute threshold refers to the smallest level of the light that a
person can detect.
o In smell, for odors, the absolute threshold involves the smallest amount that
a person is able to smell.
o In the absolute threshold of touch, the amount of force required for you to
detect the feeling of feather lightly brushing your arm.
Sensory Adaptation
oThe process in which changes in the sensitivity of
sensory receptors occur in relation to the
stimulus.
oGradual decrease over time in the responsiveness
of the sensory system to a constant stimulus.
Difference Thresholds: Noticing Distinctions Between Stimuli
o Difference threshold is the smallest level of added (or reduced) stimulation required to
sense that a change in stimulation has occurred.
o The difference threshold is the minimum change in stimulation required to detect the
difference between two stimuli, and so it also is called a just noticeable difference.
o Weber’s law helps explain why a person in a quiet room is more surprised by the ringing
of a telephone than is a person in an already noisy room.
o To produce the same amount of reaction in a noisy room, a telephone ring might have to
approximate the loudness of cathedral bells.
Difference between absolute
and difference threshold
Perceptual Constancies
o Perceptual constancy refers to perceive an object you are familiar with as having a constant shape, size and brightness
despite the stimuli changes that occur.
o The tendency of animals and humans to see familiar objects as having standard shape, size, color, or location regardless
of changes in the angle of perspective, distance, or lighting.
o Size constancy : Recognizing that an object is the same size, even if it
looks smaller from a distance
o Shape constancy: Recognizing that an object has the same shape, even if
it's turned around
o Color constancy: Recognizing that an object has the same color, even if
the lighting changes
o Size constancy is the ability to perceive that
an object's size remains the same even when
its distance from the observer changes.
Shape constancy
o You perceive a table as rectangular
regardless of the angle from which
you view it.
Illusions
o An illusion is a perception that doesn’t correspond to reality.
o You think you see something when the reality is different.
o Visual stimuli that fool the eyes.
o False Perception
Muller-Lyer illusion.
The Müller-Lyer illusion is an optical
illusion that makes two lines of the
same length appear different in
length. It's one of the most well-
known optical illusions in
psychology.
o The Ponzo illusion is a type of geometrical-
optical illusion that makes two horizontal
lines appear to be different lengths, even
though they are actually the same.
Infinity Mirror
Infinity Mirror
o https://www.youtube.com/shorts/KWgkBroB38M
o https://www.youtube.com/shorts/rJEplYePZng
o https://www.youtube.com/watch?v=HHiGcYHBDuk
Thankyou
Any Questions???
