EXPERIMENT
Topic
Muller Lyer Illusion
Problem
To
study the amount of optical illusion with the application of the Muller Lyer
Card.
Introduction
We
are living in the world of stimuli which are simple and complex. The cognition
or knowledge of these stimuli is a perception and this process of perception is
carried out by the means and materials provided by our sensations. We must
remember that sensations only provide us sensory qualities, such as color, odor
and taste of the stimuli or objects. When these sensory qualities are processed
and referred back to the object, we have the perception. Thus in perception sensations are objectified
and given meanings provided by our memory. Hence some experts consider
perception as :- Sensation+ Meaning =Perception
Generally
these are perceived as correctly but sometimes the individual fails to perceive
them in its true perspective, rather perceives erroneously. This sort of false
perception is an illusions arise from all kinds of sensation and will be
connected with sight, known as optical illusion.
Different
Principle theories such as:
Ø The eye movement theory
Ø The perspective theory
Ø The empathy theory
Ø The confusion theory
Ø The good-figure theory elaborately explains the various causes of
illusion.
However
briefly some causes are appended below:
Ø Illusion due to abnormal conditions of the sense organs.
Ø Illusion due to the limitations or deception of the senses.
Ø Illusion due to the state of the mind at a particular moment.
Ø Illusion due to the odd managements at the stimuli.
For the study of optic illusion,
Muller layers figure is well known. This adjustable figure contains two lines,
the one which is constant and used as a standard, is arrow head while the other
is variable and has FEATHER LIKE ENDS. The
arrow and the feather ends are responsible for causing illusion.
The following experiment carried out
with Muller Lyer card will illustrate the comparative illusory effect.
Hypothesis
During the descending order there will be more illusion as compare
to the ascending order.
Apparatus
and Material
Muller Lyer card, paper, pencil, calculator.
Experimenter
A.B.C
Subject
X.Y.Z
Instructions
After
informal conversation, I imparted the following instructions to the subject.
Prior to the start of the experiment
you will be given two cards bearing an arrow head and the second with feather
like ending. The arrow head card is constant while the second is movable.
You will hold the constant card in
your left hand while the movable card will be pulled out maximally. You will
make horizontal line equal to the other with your right hand. The error will be
measured and the test will be repeated ten times. Each time error and
variability will be noted. Similarly the experiment will be repeated with the
left hand. After twenty descending trials, the experiment will be carried out in
an ascending order. You(subject) will hold the constant part of the adjustable
figure in your left hand with complete insertion of the sliding part. You will adjust
the sliding part till the two main lines appear equal. This process will be
repeated ten times with the right hand and ten times with the left hand. Errors
and variability of each trial will be noted.
Procedure
After impartation of the instructions the constant side of the card
was handed over in the left hand, while the movable side was pulled outward
maximally. The subject started sliding inward the moving side with his right
hand. When the subject felt that the line is equal to the other( standard
line), the error and variability was measured on the scale printed at the
backside of the figure. The test is repeated ten times and every time error and
variability was measured and entered in the table.
While holding the constant side of the card in the right hand the
subject tried to make the moving line equal to the standard line with his left
hand. With his hand ten trials were completed. Errors and variability were also
recorded.
After these twenty trials the standard line was placed in the left
hand with moving line completely inserted in the pocket of the figure. This
time the subject with right hand pulled out the sliding part till the two lines
appeared him equal. After ten trials with this hand, the constant (Standard
line) figure was held by the right hand and the subject pulled out the inserted
line with opposite hand till it appeared him equal to the standard line. After
the completion of 40 trials, measured errors were tabulated for the
determination of constant error and point of subjective equality. The subject
while making the feather end line equal to the standard line committed a
regular
error. The average of the constant error is 19.3mm.
Constant
Error (CE)
An
error occurring in psychological experiment, because of some factor, which exercises
a constant influence is called average error. In this experiment, the subject while
making the feather end line equal to the standard line committed a regular
error during the 40 trials. It is because of an illusion.
Point
of Subjective Equality (PSE)
The value of a variable which will
be judged equal to the stimulus (Standard line) more frequently. In this
experiment the measurement of the feather end line as compared to the standard
line (60mm) is a point of subjective
equality.
Subjective
Report
Today
a class fellow of mine requested to join her as a subject in an experiment of
psychology. In this experiment I have to make a line equal to the other line.
Apparently it was a simple task. Enthusiastically I joined the experiment and
made the required line equal to the other one. I was asked to repeat the
experiment again and again and this appeared to me a futile exercise.
When the measurement of each trial
was told, I was utterly surprised to know that I could not make the line equal
to the standard line even in a single trial. Then I asked the reason of my
failure. I was told that it is because of the arrow and feather end lines.
Experimenter's
Report
The subject participated in the
experiment voluntarily. She equalized the lines very confidently. The
repetition of the trials appeared her a fool's errand. After the completion of
the experiment when she was informed of the failure, she could not believe it.
Then she was shown the back side scale, that in – spite of the line make equal
to the standard line still the scale indicated variation, therefore, she has to
believe it with a surprise.
Results
For
the determination of PSE, all values are
added and divided by the total members of trials:
Table
Showing Measurement of Each Trial
Table
|
Trials with
Right Hand
|
Trials with
Left Hand
|
|||
Des. Order
|
Asc. Order
|
Des. Order
|
Aes.Order
|
||
1
|
60mm
|
48
|
42
|
42
|
40
|
2
|
60mm
|
49
|
41
|
40
|
41
|
3
|
60mm
|
53
|
43
|
41
|
40
|
4
|
60mm
|
49
|
40
|
40
|
41
|
5
|
60mm
|
49
|
38
|
39
|
39
|
6
|
60mm
|
49
|
41
|
41
|
40
|
7
|
60mm
|
50
|
39
|
40
|
42
|
8
|
60mm
|
51
|
42
|
40
|
39
|
9
|
60mm
|
52
|
39
|
41
|
40
|
10
|
60mm
|
49
|
41
|
40
|
39
|
Total
|
499
|
406
|
404
|
401
|
|
PSE=
Right Hand( Asc. order)+ R.H Dec.+ Left Hand(Asc. Order) +L.H.(Dec.order)/40
= 499+406+404+401/ 40
=1710/40 mm
=42.75
CE=
Standard line – point of subjective equality(PSE)
=60mm – 42.75mm
= 17.25mm
While equalizing the lines, my
subject committed an average error of 17.25mm.
This
means, the subject considered the average length of 42.75mm of the variable line
equal to the length of 60mm of the standard line. The average illusion during
the 40 trials stands 17.25mm. during ascending order the average illusion is
40.35mm, whereas in descending order the average is 45.15mm. this variation also
supports the hypothesis.
As
table showing:
Left hand
Ascending + Right H. Ascending
|
Right hand
Descending + Left H. Descending
|
401mm+406mm/
20
|
499mm+404 mm/
20
|
40.35mm
|
45.15mm
|
It's very helpful
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