Lady Bugs and Cell Phones
Research Methods in Psychology
Then and Now
Presented in PSY 3384
University of The Incarnate Word
February 24, 2005

Harold Rodinsky MSc.
Research Methods
• Our curiosity leads us
– To ask a question
– About some
• Observation
• Our first task
– Is to define
• The observation of
interest
– So that we can..
Research Methods
– Creating An
operational definition
• That allows us
• To evaluate our
observations
– Rather than
• Speculate about our
observation
Observation
•
•
•
•
•
•
I see students walking to class
A lady bug lands on the arm of one of the students
The student doesn’t realize the ladybug is on her arm
one her friends tell her about the Lady Bug
OBSERVATION OF INTEREST…………
Why didn’t the student know that the Lady Bug was on
her arm?
How to Define the Observation
• We could speculate
– The student was to
busy to notice !!!
• Speculation provides
no information about
our question
• What can we
measure ?
– the weight of the lady
bug
Operational Definition
• Does measuring the
Lady Bug
– tell us
• why the student didn’t
sense the lady bug
– Or does the weight of
the ladybug
– raise another
question ?
The Beginning of Experimental
Psychology
• British Empiricists
– Sensations were the only source of knowledge
• Bessel demonstrated
– Individual differences
• In sensation & perception
• Physiologists
– Were defining the
• structure & function
• of the senses
The Inquiry of Experimental
Psychology
• With these advancements in place
– It was time to experiment with
– And measure
– The MIND
• To methodologically
– and scientifically investigate
• The subjective
• Experience of sensation
The First Four
• Credited with the application
– Of experimental research methods
– To the study of the mind
•
•
•
•
Herman von Helmholtz
Ernst Weber
Gustav Fechner
Wilhelm Wundt
Herman von Helmholtz
(1821-1894)
• Researcher in many
fields
– Physics
– Physiology
– Experimental
Psychology
• Speed of neural
impulse
• Reaction times for
sensory nerves
• Theory of color vision
Ernst Weber
(1795-1878)
• Weber did research
– On the perception
– Of weight
• This lead to
– Two-point threshold
• minimum distance
• Between sensations
• That can be detected
– This work lead to
• Just Noticeable Difference
• Smallest difference between weights
• that can be detected
Weber’s Contributions
• Discrimination of two sensations
– Depends on a ratio between them
– Not absolute difference between weights
• Not a direct correspondence
– Between sensation and perception
– Did not appreciate this in terms of psychology
• Weber’s work the measurement of
sensation
– Still in use today
Gustav Fechner
(1801-1887)
• Studied many fields
– Proposed two ways to
measure Sensation
• First
– Is the stimulus present
– Or absent ? (yes/no)
• Second
– Measure the intensity
– of stimuli
– When reported as
present and is called
– Absolute Threshold
– Differential Threshold
• The least amount of
change that gives rise to a
new sensation
Wilhelm Wundt
(1832-1920)
• Father of Modern Psychology
– Formalized psychology into academic
discipline
– Set up first laboratory for psychological
research
• Research focus CONSCIOUS EXPERIENCE
– Social Psychology
– Stages of cognitive development
» Expressed in art, literature, myth
» Social customs and morals
Wilhelm Wundt
(1832-1920)
• Father of Modern
Psychology
– Formalized academic
discipline
– first laboratory for
psychological research
– Research focus
CONSCIOUS
EXPERIENCE
Absolute Threshold
• Lady bug
– Absent or present ?
• Above or below
• Absolute threshold
• If the Lady Bug isn’t
noticed
– It is below
– absolute threshold
• Can we discriminate
– Between one and two
lady bugs?
Discrimination Experiment
• Lets’ find out
– We need
•
•
•
•
Cotton balls
Paper cups
12 participants
12 assistants
Two Point Threshold
• What if two Lady
Bugs
– land on your arm ?
• Weber’s research
– “…there is a threshold
– Where you can’t tell
• If it is two lady bugs
• Or one lady bug
Two-Point Experiment
• Lets measure
– The two-point
threshold
– We need
•
•
•
•
•
•
4 participants
4 blindfolds
4 dividers
4 rulers
4 assistants
1 blackboard
Results
• Absolute Threshold
– Subject to individual
differences
• Was the lady Bug
detected
– Yes/no
– If no below threshold
– If yes above threshold
• Discrimination Test
– The smallest change
in stimuli
• That is detectable
• Two-Point Threshold
– Subject to individual
differences
• By two-point threshold
testing
– We can measure
• the smallest distance
between two points
– That is detectable
Discussion Absolute Threshold
• Absolute Threshold
– Do I feel the key
depress when I press
it?
– OR
• Do I select
– Key sound option
• So I can HEAR
• Rather than feel
• the key has been
depressed
Discussion Discrimination
• The smallest change
in stimuli detectable
– Are the keys uniform
– All the same ?
– OR
• Are there slight
• Differences
• So we can sense the
difference?
– Look at your #5 Key
Discussion Two-Point Threshold
• How far apart are the
keys on my cell
phone?
– Can I feel the
difference between
keys
– Or do I feel just one
key?
Summary Discussion
• The research methods we demonstrated
– Are from the earliest days in the history of
psychology
• These studies answer fundamental questions
– Produce fundamental theories
• That are still pertinent today
– Used in designing consumer products
– In medical testing