2. Sensation
• The process of detecting a stimulus (something that attracts
the attention of a sensory organ)
• the stimulation of sensory receptors and the transmission of
sensory information to the central nervous system
Five Traditional Senses:
• Vision
• Hearing
• Touch
• Taste
• Smell
3. Sensation Sensory Receptors: located
in the sensory organs
• cells that convert physical energy in the environment or
the body to electrical energy that can be transmitted as
nerve impulses to the brain
• Eyes
• Ears
• Nose
• Tongue
• Hands
4. Thresholds
• minimum amount of any given sensation that has to be
present for us to notice it
• E.g: Ticking of a watch from 20 ft away
Absolute Threshold:
• minimum amount of a stimulus that is necessary for us to
notice it 50% of the time
• 1 drop of perfume in a small house
Just Noticeable Difference: (Difference Threshold)
• Smallest amount of difference in amount of stimulation that a
specific sense can detect (difference in shades of two colors)
E.g: Smallest difference in the shades of red your eye can see
5. Cont..
Sense Absolute threshold
smell A drop of perfume diffused throughout a six-room
apartment
Taste One teaspoon of sugar in two gallons of water
Touch An insect’s wing falling on your cheek from a height of
about half an inch
Hearing The tick of a watch at 20 feet in a quiet room
sight A candle flame 30 miles away on a clear, dark night
6. Sensory Adaptation
• process by which we become less aware of weak stimuli
• if a stimulus is unchanging, we become desensitized to it
• We adapt to lying on a beach by becoming less aware of
weak stimuli like the sounds of the ocean
• We adapt to living near a highway by becoming less aware
of the sounds of traffic
7. Sensory Overload
• Can use selective attention to reduce sensory overload
• Selective Attention focusing of attention on selected
aspects of the environment and the blocking out of others
8. The Eye
• Cornea
Protects eye and bends light toward lens
• Lens
Focuses on objects by changing shape.
• Iris
Controls amount of light that gets into eye.
• Pupil
Widens or dilates to let in more light.
9. The Eye
• Retina
Neural tissue lining the back of the eyeball’s interior, which contains the
receptors for vision.
• Rods
Visual receptors that respond to dim light.
• Cones
Visual receptors involved in color vision. Most humans have 3 types of cones.
10. The Ear
• Loudness
The dimension of auditory experience related to the
intensity of a pressure wave.
• Pitch
The dimension of auditory experience related to the
frequency of a pressure wave.
• Timbre
The distinguishing quality of sound; the dimension of
auditory experience related to the complexity of the pressure
wave.
11. The Ear
• Auditory Localization:
Sounds from different directions are not identical as they
arrive at left and right ears
• Loudness
• Timing
• Phase
The brain calculates a sound’s location by using these
differences.
12. The Ear
• Three theories on how we perceive sound:
• Frequency Theory
Neural impulses are stimulated more with higher frequencies of air
waves
• More plausible for small frequencies, rather than high frequencies
because we can hear freqs higher than the maximum rate of neural
firing (1,000 neurons a second)
• Place Theory
Different frequencies of air waves activate different places along the
basilar membrane
• Volley Theory
Neurons fire out of sequence to add up to a certain Hz
13. Smell
• Olfaction Lock-and-key
• Detects molecules in the air
• Olfactory receptors (i.e., the locks) are built so that only
molecules (the keys) with particular shapes will fit in
particular receptors
• Receptors send neural signals to the brain, passing the
thalamus (memory) and the limbic system (emotions)
along the way
• This is why odors often trigger emotional memories
14. taste
Process
• Sense of taste combines with the sense of smell to produce perception of
flavor of food
• Research suggests that neural impulses for both senses converge to some
degree in brain area associated with the perception of flavor
• When the sense of smell is blocked, we have a harder time detecting most
flavors
15. Skin Senses Touch
• Skin is the body’s largest sensory organ
• Millions of skin receptors mix and match to produce
specific perception
• Four basic types of sensations
• Pressure
• Warmth
• cold
• pain
16. Skin Senses Temperature
• Two separate sensory systems – one for signaling warmth
and the other for signaling cold
• Also have distinct spots on the skin that register only
warmth or cold
• If you activate both at the same time, the person
perceives ‘hot’!
17. Skin Senses Pain
Pain serves a function
• it warns us of impending danger Endorphins
• Neurotransmitters in the brain that have a pain-killing
effect
Gate-control theory
• Pain impulses can be inhibited by closing of neural gates
in the spinal cord
18. Body Senses
Kinesthetic sense
• Provides info about position of joints, muscles, limbs
• Gives us control over body movements
Vestibular sense
• Provides info about body’s orientation relative to gravity
and head’s position in space
• Helps us maintain balance
• Relies on semicircular canals in the inner ear
19. Perception:
• process by which the brain organizes & interprets sensory
information
• uses sensory information to form a meaningful pattern
• final, organized, meaningful experience of sensory information
An example:
• Have you ever started the car and had to quickly turn down the
volume on the radio from where it was set last time you were in the
car?
• The level of energy (I.e., loudness) of the radio hasn’t changed
• (the volume know remains in the same place as when you last had it
on),
• but your perception of the loudness has changed drastically!
20. Influences on Perception
• Our needs affect our perception because we are more
likely to perceive something we need
• Our beliefs can affect what we perceive
• Emotions, such as fear, can influence perceptions of
sensory information
• All are influenced by our culture.
• Expectations based on our previous experiences influence
how we perceive the world.
21. Perceptual Set
• What you see in the centre figures depends on the order in which you look at
the figures:
• If you scan from the left, see an old woman
• If you scan from the right, see a woman’s figure
22. Context Effects
• The same physical stimulus can be interpreted differently
• We use other cues in the situation to resolve ambiguities
• Is this the letter B or the number 13?
23. Rules of Perceptual Organization
• Gestalt Principles of Vision:
• notes the various ways people make sense of sensory
information through:
• Figure-Ground
• The recognition of objects against a background
• What we perceive as the object & perceive as the
background influence our perception
25. Rules of Perceptual Organization
Proximity
• Grouping together visual & auditory stimulus which are near
to one another
• Marks near one another tend to be grouped together
• What do you see?- 3 rows of dashes or 36 dashes
Similarity
• Tendency to group elements together that look alike
• Marks that look alike tend to be grouped together
• What do you see?- 3 columns of red or a 4 x 6 pattern
26. Rules of Perceptual Organization
Closure
• We tend to fill in gaps in what your senses tell you
Continuity
• Marks that tend to fall along a smooth curve or a straight
line tend to be grouped together
• People prefer to see smooth continuous
patterns not disrupting ones
28. Cont..
Convergence:
• Turning inward of the eyes, which
they focus on a nearby object.
Retinal Disparity:
• The slight difference in lateral
two objects as seen by the left eye
eye.
29. Depth and Distance
Monocular Cues
• visual cues to depth or distance that can be used by
one eye alone.
• Cues create the illusion of three dimensions or depth
on two-dimensional or flat surfaces
• Cause certain objects to appear more distant than
others
30. Visual Constancies
• The accurate perception of objects as stable or unchanged despite changes in
the sensory patterns they produce.
• Size constancy
• Color constancy
• Brightness constancy
• Shape constancy
31. Size Constancy
• the tendency to perceive an
object as being of one size no
matter how far away the object
is
32. Color Constancy
• the tendency to perceive an object
as keeping their color
• even though different light may
change the appearance of their color
33. Brightness Constancy
• the tendency to perceive an object as being equally bright
• even when the intensity of the light around it changes
34. Shape Constancy
• the knowledge that an item has only one shape
• no matter what angle you view it from
• even though these images cast shadows of different shapes, we still see the
quarter as round
35. Illusion or perceptual illusion
• The misperception of the true characteristics of an object or an
image.
• Illusory Contours: How Many Triangles Do You See?
• The Gestalt principles of perceptual organization contribute to
the illusion of triangular contours in this image.
• you instantly reverse figure and ground so that the black circular
regions become the ground,
• while the white region is visually favored as the figure.
• . The images produce a second intriguing illusion:
• The pure white illusory triangle seems brighter than the
surrounding white paper
36.
37. The Müller-Lyer Illusion
• Compare the two photographs.
• Which corner line is longer?
• Now compare the two line drawings.
• Which center line is longer?
• In reality, the center lines in the photographs and the line drawings
are all exactly the same length
• which you can prove to yourself with a ruler
38. moon illusion
• A visual illusion involving the misperception
that the moon is larger when it is on the
horizon than when it is directly overhead.
The Moon Illusion Dispelled
• The moon illusion is subjectively very
compelling.
• When viewed on the horizon, the moon
appears to be much larger than when it is
viewed higher in the sky.
• But as this time-lapse sequence of the moon
rising over the Seattle skyline shows, the size
of the moon remains the same as it ascends
in the sky.
39. Extra Sensory Perception
• Extrasensory perception (ESP) is perception that occurs
independently of the main physical senses
• (sight, hearing, touch, taste and smell or, indeed, perceptual
processes such as proprioception)
• In some ways the term is vague but it is generally used to imply
a source of information that is unknown to modern science
40. Types
• Telepathy
• Clairvoyance
• Precognition and Retrocognition
• Experimental evidence
a) Restricted-choice experiments
b) Free-response experiments
41. Telepathy
• the source of information is another person’s mind
• The principle requirement of telepathic transmission is that the information transfer
cannot be explained by any known physical process
• Often the demonstration involves information transfer over large distances
• Unlike physical information transfer, telepathy is not subject to the weakening of the
signal the further you move away from the source
Clairvoyance
• we can propose clairaudience where the source of information is auditory rather than
visual
• Clairaudience is an alleged psychic ability to hear things that are beyond the range of
the ordinary power of hearing
• such as voices or messages from the dead
Precognition and retrocognition
• clairvoyance or clairaudience concerns things in the future or the past the these are
referred to as precognition and retrocognition respectively
• Dreams have sometimes been related to precognition
• Retrocognitions can be about recent events
• (e.g. the perpetrator of a recent murder) or distant events (e.g. historic events)
Retrocognition is different from past life regression
42. Experimental evidence
• experiments fall into two broad categories
• Restricted-choice experiments
• The receiver must make a decision about what is being transmitted from a
small set of known possibilities
Free-response experiments
• Here the sender will choose an item from a large but finite set of possible
stimuli
• The receiver is not told anything about the nature of the chosen stimulus
The remote viewing you participated in was a free-response set up.
