This document discusses perception and perceptual errors. It defines sensation as the immediate response of sense organs to stimuli, while perception involves meaningful interpretation of sensations based on past experiences. Perception provides knowledge about selected sensory information and prepares the body for response. Factors like sense organs, brain, emotions, and expectations can influence perception. Principles of perception include figure-ground relationship, closure, grouping, and contrast. Perceptual errors include illusions, where perception differs from reality, and hallucinations, where perception occurs without stimuli. Common illusions are of size, length, perspective, curvature, and movement.

1. Perception
&
Perceptual Errors
Mr. Johny Kutty Joseph
Assistant Professor
SMVDCoN

2. Sensation
• Sense organs - Gateways of knowledge
• Knowledge is realized through sense
organs
• Immediate result of sense organ being
acted upon by appropriate stimuli
• Derived from the stimulation of the
sense organs or receptors

3. Name of the
sense organ
Name of the sense Sensation
Eyes Visual sense Vision
Ears Auditory sense Hearing
Nose Olfactory sense Smell
Tongue Gustatory sense Taste
Skin Tactile sense Touch

5. Perception
• Perception = Sensation + Meaningful
Interpretation
• Perception is the first event in the chain which
lead from the stimulus to action.
• Process of getting to know objects and objective
facts by the use of the senses
-R.S. Woodworth and D.G. Marquis
• Perception is the organizing process by which
we interpret our sensory input.
- Edmund Fantino, 1975

6. Characteristics
• Perception is a process: It is not a product or outcome. It
is initiated by input and followed by output/response.
• Perception involves sensation: sensation precedes
perception.
• Perception needs the presence of stimulus: like sensation
perception also occurs in response to stimulus.
• Perception provides knowledge about the selected
information: all the stimuli are not perceived. We select
the sensory impressions.
• Perception is preparation to response. It is the first step
toward reaction/response/behavior of an organism. It
helps in preparation of self.

7. Characteristics
• Past experience plays a role in perception. The past
experiences may be direct or indirect. Eg. Perception of
a fruit such as likes or dislikes.
• It is individualized. Different individuals do not perceive
objects or events or relationships in the same way. It is
always influenced by expectations, motivation etc.
• It involves organization. We perceive a thing as a whole
not fragmented. It tries deriver the relevant meaning of
all sensory impressions or sensations related to a
particular stimulus.

8. Factors affecting Perception
1. The sense organs.
2. Brain
3. Past experience.
4. Learning.
5. Emotions.
6. Interest.
7. Motives.
8. Self concept.
9. Expectations.

9. Principles of perception
1. The principle of figure –ground relationship.
2. Principle of closure
3. Principle of grouping.
4. Principle of simplicity
5. Law of Pragnanz.
6. Principle of contour.
7. Principle of Context.
8. Principle contrast.
9. Principle of distance and depth.
10.Principle of motion.

10. The principle of figure –ground relationship.
• A figure is always
perceived in relationship
to its background.
• We experience a figure
against a background or
background against a
figure based upon the
characteristics of the
perceiver.
• The given pattern may be
perceived either as a vase
or as two faces.

11. The principle of closure
• While confronting an
incomplete pattern one
tends to complete the
pattern or sensory gaps
and perceive it as
meaningful whole.
• This is helpful in
interpreting various
incomplete objects or
patterns in the
environment.
• Though the Panda is not
complete still we

12. The principle of grouping
• It is a tendency to perceive
a stimuli in organised
meaningful patterns. It
may be based on
1. Similarity: objects look
alike are grouped
together. (group of dots)
2. Proximity: objects that
appear close are grouped
together. (8 lines)
3. Continuity: Grouped
based on the
continuation.

13. The principle of simplicity
• We tend to perceive a stimulus in such a way that in the
simplest possible pattern.
• The characteristics like symmetry, unbroken lines and
compact areas and the perceivers familiarity with the
figure contribute to its simplicity.

14. The law of Pragnanz
• We perceive a figure
in its good and
proper form instead
of the incomplete
,imperfect, ugly or
broken ones.
• It is also similar to
principle of
simplicity.
• The given figure
appears as
overlapping square,
triangle and circle.

15. • Principle of contourWe perceive a figure in its contour
an it is the boundary between a figure and background.
We can perceive different figures and sketches with
their appearance, sizes and colours only when they
have been marked separate. In the given we cannot
separate the margin of colours as they lack contour.

16. • Principle of Contrast: We perceive a figure larger or
brighter in relation to its background. In the given
picture the the blue dot is brighter compare to the
background. In the first picture the blue dot appears
larger to background and vice versa in second picture.

17. • Principle of context: a rain may be perceived by farmer
as blessing and hell for a tourist.
• Principle of distance and depth: Throgh this principle
we are able to see the distance of an object based on
its size. Also we can measure the depth of something
based on the perception. Even an infant has this
ability.
• Principle of Motion. There is movement around all of
us. Motion perception is based on change of position
and comparison against background.
Eg. Hills don’t move but nearby trees move during a
travel.

18. Determinants/Factors of Perception
• The nature of stimulus: size, color, intense pain etc.
• The health and functioning of sense organs.
• Past experiences with stimulus. Recognizing toys by
kids. Fearful/friendly parameters.
• Learning and training. Expertness of profession
changes perception. Eg. Gold recognition by woman.
• Nature of attention to stimulus. Enforce/spontaneous.
• Maturation. Age and maturity improves perception.
• Context of perception. A smile perceived as
welcoming and teasing in different occasion.
• Interest purpose and motivation.
• Mental and emotional status.

19. Errors in Perception
Errors on account
of defects in
perceptual organs. Illusion
Errors on account of
defects mindset and
time of perception. Hallucination

20. Perceptual errors
1. Errors due to defects in sensory organs: Since
the sense organs are gateway of knowledge.
Deafness, blindness etc.
2. Errors due to improper mindset and time of
perception. Eg. Misperception of a letter based
on the people who are exchanging it. It includes
ones mental set up, instincts. We may get afraid
of shadows, movements, as thieves and devils.
We may recognize a stranger as our relative.

21. Perceptual errors
1. Illusion: these are faulty perceptions. Eg.
Looking horizon as the meeting place of sky and
earth.
2. Hallucination: perception of stimulus in the
absence of the stimuli. It may a sound, smell,
vision, taste, touch. This is one of the marking
feature of psychosis.

22. Types of Perceptual Illusions.
1.Illusion of size.
2.Illusion of length.
3.Optical Illusion
4.Illusion of perspective.
5.Illusion of curvature.
6.The horizontal-vertical illusion.
7.Illusion of movement.

23. Illusion of size.
1. It provides false
perception of the size
of the object.
2. A football in child’s
hand appears larger
than that in an
adult’s hand.
3. In the given
illustration compare
the size of black circle.

24. Illusion of length
1. It provides false
perception of the length
of the object.
2. It is also called as Muller
Lyre Illusion.
3. All the lines are of equal
size but the direction of
arrow mark decides the
perception of length.

25. Optical Illusion
1. An optical illusion is an
illusion caused by the
visual system and
characterized by visually
perceived images that
differ from objective
reality.
2. The information gathered
by the eye is processed in
the brain to give a percept
that does not tally with a
physical measurement of
the stimulus source.
3. It is also called a visual
illusion

26. Optical Illusion

27. Illusion of Perspective
1. It is caused on account of misleading perspective cue as we
hasten to add a third dimension.
2. The top barrel looks larger because it appears to be far
away.(A looks larger than B)
3. It is also called Ponzo Illusion

28. Illusion of Curvature
1. Although these lines AB and CD are horizontal, straight
and parallel, yet they appear to be bowed.
2. These illusions of curvature are supposed to be the result
of eye movements and a tendency to overestimate acute
angles.

29. The Horizontal-vertical Illusion
1. You mat seem to say that
vertical line is longer and
horizontal one is smaller.
2. Bothe the lines are of actual
length and

30. Illusion of movement
1. Quite often we perceive movement when the objects we
are looking at, are actually not moving at all.
2. Such faulty perceptions are called illusions of movement.
They are;
a. Auto kinetic illusion: if we enter a room that is completely
dark except for a small spot of light and stare at it for few
second we perceive the light is moving around us.
b. Induced motion: when we watch sun or moon we feel its
movement above the cloud but on actual cloud is moving.
The same happens during train journey.
c. Stroboscopic movement: the technique by which we
perceive a motion picture/movie by movement of still
pictures in a series.

31. THANK
YOU