This is a five-section course as part of a two-course sequence in Research Methods in Psychology. This course deals with experimental methods whereas the other course dealt with descriptive methods.
Lesson 2A: Theory
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Del curso dictado por Georgia Institute of Technology
Experimental Research Methods in Psychology
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Hypotheses
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Dr. Anderson D. SmithRegents’ Professor Emeritus
School of Psychology
Hi, Anderson Smith here, and we're talking about experimental research methods.
And let's review the process of doing an experiment in psychology.
First you have to have a rationale for doing the experiment, and
there can be many ways of doing that looking at the research literature,
having a theory, just making observations about behavior, or
having some problem which it's trying to solve.
Then you actually form an hypothesis, the question you're going to ask in your
experiment based on the rationale for doing the experiment.
And once we have every search question or hypothesis,
then we make the manipulation of the independent variable.
And we measure our dependent variable.
That's the empirical study of the actual experiment.
We get the results of that, the dependent variable.
We do a data analysts to tell us whether or not there's a meaning
dependent variable difference due to the independent variable.
And then we actually interpret those findings.
And then the conclusions we reach are fed back Into the literature so
that other people can benefit by the fact that we'd done an experiment and
expand their knowledge about the topic that we're interested in.
So the rationale is the first thing we're going to talk about.
How do we determine what a hypothesis actually is.
And as I mentioned we can do that in many ways.
The hypothesis, which is some relationship between the dependent variable and
the independent variable can be counted through observation, through the research
literature, or through a theory that we have about how the dependent variable and
the independent variable are supposed to relate to each other.
So let's first talk about observation.
And I want to use a demonstration of that
from one of my favorite series of experiments
by Vincent Dethier at Princeton who is actually a behavioral biologist.
And he was interested in studying the housefly.
He said he studied houseflies because when you have that as your subject, houseflies,
you don't have the animal rights people telling you what you can do and can't do.
In fact, when people come to your office,
you have to keep them from doing away with your subjects by swatting them.
So nobody really worries about flies, but
they're very interesting creatures according to Dethier.
And he just was observing the flies,
he noticed something very interesting about them.
He noticed that when they were eating,
they walk around on their food before they eat.
That's not what we do, but it's what houseflies do.
You can always tell when a fly is eating or drinking because it has that proboscis,
when it's not eating or drinking, it's rolled up into the head.
But when it is eating or drinking it's rolled out as you can see here, and
actually you can know when the independent variable is taking place,
the fly is feeding.
So he said, why do they walk around on their food before they eat?
That is an observation.
Why can't I come over with an hypothesis based on that observation.
Well, maybe houseflies actually taste with their feet.
Not like us who have taste buds in our mouth and
on our tongue that tell us when something is what we want to eat.
And actually, it allows us to spit it out if it's something we don't want to eat.
Well, maybe the reason the housefly walks around on
the food before it eats is it actually has taste buds located on their feet.
That was his hypothesis.
Now how do you test that?
Well, first he jut actually hooked a little housefly to a rod so
he could move the housefly away.
And he said what I'll do is I'll change where the feed are,
relative to where the head is.
If I give the fly just plain water, and it's hungry, it won't drink or eat.
because it's not thirsty, it's hungry.
If I give the fly sugar water and it's hungry, it will eat.
So maybe I'll put the head over sugar water and the feed over plain water, and
if the taste is determined by the head like it is in most organisms,
then of course the fly will eat.
But if I put the head over plain water in the feed over sugar water,
then the fly, if it uses its feet to taste,
then the fact that its feet is over the sugar water, then it should eat.
So here's my manipulation, where the head is relative to where the feet is
to tell me whether or not the taste is located in the feet, or in the head.
That was his experiment, and this is what he did.
He put the fly down so its feet was in plain water, and
the head was over the sugar water, which is what it's looking for,
the proboscis never comes down, the fly doesn't eat.
But if I change it and put the head over plain water and
the feet over sugar water, even though it's only drinking plain water,
it's not satisfying its hunger, the fly eats.
So he was able to show with an experiment
that the fly actually tastes with its feet.
It's feet determines whether or not it is good to eat, not the head or
the proboscis or the mouth or even the smell, if the fly smells with the eyes.
It's the feet that determines whether the fly is eating or not.
So what did the conclusion, fly tastes with its feet,
in an experimental method was sort of satisfied.
His observation was that flies walk around on their food before they eat.
His hypothesis were that fly tastes with its feet.
The manipulation was whether the feet or
the head were over the sugar, and the head or the feet were over plain water.
He found out through a data analysis that in fact the fly eats when
its feet are over the sugar and not the head over the sugar.
So the conclusion, fly tastes with its feet.
And he wrote a great book about behavior in the fly called To Know a Fly.
If you have a chance to read that, there's lots of other experiments he did with
house flies to really understanding feeding and the fly.
So this is example where simple observation can lead to an hypothesis.
Another way of doing it is to use a theory.
And a theory is basically a set of statements that describe general
principles about how variables relate to each other.
In other words, we have a theory sort of an organised set of principles that allows
us to predict what will happen when we manipulated the independent variable and
measured a dependent variable.
If you actually look in the dictionary, it states a theory is an idea or set of ideas
that is intended to explain facts or events, that's exactly what a theory is.
And they've been actually lots of theories that guide.
In fact, I would say that's the number one reason we do experiments,
is to test a theory.
So what makes a good theory?
Well, first a good theory is one [LAUGH] that's supported by the data.
It's the one that actually has facts that support it.
Also good theories are falsifiable.
That is, if you're going to test hypothesis,
you have to be able to find negative results as well as positive effects.
So the theory itself has to have experiments that can falsify the theories,
that can fail to support it as well as support it.
Also good theories have parsimony, that is, they're simple.
It's a simplest way of describing the phenomena, and
that's what parsimony means.
So you don't want to have a very,
very complex theory when in fact the simple theory will do just as well.
And good theories don't prove anything.
The theory is not the proof, it's the hypothesis
that's tested that provides the data that provides the proof of the theory.
And now let's talk about some theories in psychology and what they really represent.
One of the most common one is the difference between psychodynamics theory
of Sigmund Freud, and behavioral theories, people that would generate,
theories that would generate about people like B.F. Skinner.
And either behavior theories or
psychodynamic theories is the number one theory that determines what analysis,
what therapy you use in treating abnormal behavior.
Psychodynamic theory comes to psychoanalysis,
which says that your abnormal behavior is due to internal conflicts you
had that were developed when you were very, very young, even your infancy.
And behavior theory says your abnormal behavior is simply behavior
that you learned.
And you learned the wrong things.
The interesting thing about this is that there's very little research on
psychodynamic theory or psychoanalysis because it's not a falsifiable theory.
You cannot come up with predictions or
hypothesis that leads to either support or lack of support for the theory.
Because you are dealing with unconscious behaviors that happen to you
many many years ago.
Well, behavior theory is tested all the time, because we will simply look at
reinforcement and punishment and have it determine what your behavior is.
So here is the example of a good theory even though the psychoanalysis, behavior
therapy are very commonly used in abnormal psychology by clinical psychologists.
Behavior theories are testable.
They are good theories, according to experimental research.
Well, psychodynamic theories, because of their lack of falsifiability,
are not necessarily that good.
Another big giant question in psychology is nature versus nurture.
When I watch a behavior, is that because of the genetic predisposition to
engage in that behavior or simply something you've learned.
And that there lots of research that would test this nature versus nurture idea.
The theories being its genetics, it's a biological predisposition to do something,
or it's behavioral,
it's something you simply learn because of your reinforcement contingencies.
By the way, most of these kinds of experiments end up supporting both.
That any particular behavior is due to both genetic predisposition and
learning of the environment, nature or nurture.
Another common theory in physiological psychology is the idea that
the brain is very localized for particular things.
So, one behavior is located here in the brain,
and another behavior is located here in the brain, or
whether behavior is simply generated by the entire brain itself.
And it was Walter Penfield that really by actually doing experiments with
stimulating different parts of the brain and noticing that's stimulation in certain
areas would generate certain kinds of behaviors.
For example, if I stimulating the left motor cortex,
I would get behavior in my right part of the body.
But if I generate in the right hemisphere,
in the right motor cortex, I would get behavior in the left part of my body.
If I generate it in the occipital lobe in the back of the brain,
I get visual reports, I'm seeing things.
On the auditory cortex, you actually hear things.
So he was able to show that the brain is very specialized,
different parts of the brain control particular behaviors.
Another theory that's been very, very influential in the aging area, and
as I told you aging is my research area, is socio-emotional selectivity theory.
Which says that as people grow older, they actually become more
concerned with emotional stability, and because of that,
they'll have fewer friends and colleagues they'll interact with.
So as they get older and their friends start dying,
we don't look for other new friends, we want to rely more on more on
a smaller group of people that provide us the intimate kind of relationship,
that allows us to have emotional stability and emotional regulation.
Different theories that have predicted research and
given us data that then feeds back into the literature.
Thank you.
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