Research Design and Behavioral Analysis

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Research Design and Behavioral Analysis
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Research methods

• Correlation Research used to determine if there
  is a relationship between two variables
• Least amount of experimental control
• Cannot be used to state cause and effect
  relationships

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Research methods (cont.)

• Experiment provides most confidence in
  determining cause and effect relationships.
  Manipulate the independent variable to see if
  changes occur in the dependent variable (measure)
• Amphetamine study as an example

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Research methods (cont)

• Quasi-experiment similar to an experiment
  except the independent variable (IV) cannot be
  manipulated
• IV is usually a subject variable
• Subjects are assigned to groups for particular
  reason (gender, age, ethnic group, etc.)
• Lack of random assignment reduces confidence in
  cause and effect statement
• Modification of Amphetamine study as an example

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Research methods (cont.)

• The experimental design preferred in
  psychopharmacological research most control and
  confidence in cause and effect
• Measures are usually behavioral changes that the
  drug was intended to cause and physical changes
  (side effects)
• Side effects not always bad many drugs designed
  for one purpose, but later found to be useful for
  another because of unexpected actions

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Experimental designs

• All experiments begin with a control group and
  one or more experimental groups. The two
  principle experimental designs differ in how
  subjects are assigned to the groups

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Within-subjects design

• Only one group of subjects involved
• All subjects receive all levels of treatment.
  They act as their own control and experimental
  group(s). Test before giving the drug
  baseline, then give the drug and measure any
  changes
• Advantages
• Need fewer subjects
• You know groups are equal because they are the
  same subjects
• Disadvantages
• Carry over effects measuring independent
  variable to get baseline may change subjects in
  some way
• Many times it requires more time delays between
  treatments

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Between-subjects design

• Different subjects are randomly assigned to
  different groups. Groups are assumed to be equal
  because each subject had an equal chance of being
  assigned to any group
• Advantages
• No carry-over effects
• Quick
• Disadvantages
• More variability groups may not be equal by
  chance
• More subjects required and you may not have many

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Statistical analysis

• Inferential statistics what is the probability
  that the difference between groups is the result
  of chance variations?
• Within subjects design What is the probability
  that the difference in the baseline measure and
  the experimental trials was the result of chance?
• Between groups What is the probability that the
  difference between the control group and
  experimental group(s) was due to chance?
• Convention says to use probability of 1 or 5 out
  of 100 (Plt.01 or Plt.05)
• With drug research using a P lt .01 is preferred

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Validity

• Internal validity How valid is our measurement?
  Are we measuring what we say we are measuring?
• External validity How confident are we that we
  can generalize our results from our sample to a
  whole population? Is our sample truly
  representative of our population? Could it be
  biased?

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Important issues with validity

• 1. Within groups variability the average of the
  subjects in the experimental group performed
  differently than the average of the subjects in
  the control group, but perhaps a sub-group of the
  subjects did not show a difference in
  performance.
• Example older subjects were very different, but
  younger subjects showed no change. Your study
  showed it worked for all subjects when it only
  affected older subjects

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Important issues with validity (cont.)

• 2. Use of a drug with a population not included
  in any of the samples used in the experiment.
• Examples
• 1. women excluded from testing hypertension
  drugs because of fluctuating hormones. These
  drugs used to treat hypertension in women.
• 2. Prozac used to treat children when only
  tested on adults

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Important issues with validity (cont.)

• Placebo a pill or injection that has no
  medicinal value, but causes changes because of
  peoples expectations
• Placebo effect if people given something that
  is suppose to help them, it may have an effect
  when in reality the drug had no effect. Has to
  be controlled by having the control group receive
  a placebo while experiment group receives
  experimental drug

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Important issues with validity (cont.)

• Hawthorne Effect people will sometimes improve
  because they get attention and feel that others
  are trying to help even if the drug they are
  given has no effect itself

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Experimenter bias

• A Person testing their drug has a strong desire
  for drug testing to be successful
• They know what the desired effect is suppose to
  be
• They may see the desired effect in the
  experimental group, and not see it in the control
  receiving the placebo because they know which
  group is which

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Solution to experimenter bias

• Use of multiple naïve observers who have no
  expectations about the which subjects should show
  a change
• Use of double-blind techniques. Subjects are
  unaware if they are receiving the placebo or test
  drug (single-blind), and the experimenter is
  unaware of who was assigned to get the placebo
  and who is receiving the test drug.

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Three group design

• Most frequently used drug testing design
• 1. experimental groups receives test drug
• 2. control group 1 receives placebo
• 3. control group 2 receives drug with known
  effects
• Allows 3 different comparisons
• 1. placebo to established drug was test
  sensitive enough to detect an effect
• 2. placebo to experimental drug was there an
  effect
• 3. established drug and experimental drug is
  new drug more effect or have fewer side effects

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Dependent measures in psychopharmacological
research

• Changes in observed behavior decrease in
  aggressive behaviors, decreased eating, etc.
• Changes in human performance cognitive and
  motor tests
• Self-report by subjects pain medication, on a
  scale of 1 to 10 with 1 being very little and 10
  being excruciating how do you rate your level of
  pain?

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Dependent measures in psychopharmacological
research

• Electroencephalogram (EEG)
• Measure level of arousal of the cortex small
  fast waves indicate higher levels of arousal than
  large slow waves
• Measure REM sleep deprivation of REM sleep has
  similar effect to total sleep deprivation. A
  side effect of some drugs is a disruption of REM
  sleep

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Dependent measures in psychopharmacological
research

• Perceptual measures
• Sensory difference thresholds how different do
  two stimuli have to before you are able to detect
  a difference Does a drug make you more or less
  sensitive to these differences?
• Critical frequency of fusion How fast does a
  light have to flicker on and off before you see
  it as a continuous light

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Dependent measures in psychopharmacological
research (cont.)

• Cognitive tests
• Motor tests sobriety test
• Combination driving tests

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Measuring performance in nonhumans

• Drug effects on the performance on operant
  conditioning and different schedules of
  reinforcement
• Avoidance escape tasks animals learn to avoid
  an unpleasant stimuli or they learn to escape an
  unpleasant stimuli they cant avoid
• Anxiety reducing drugs decrease avoidance
  behavior but not escape behavior

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Measuring performance in nonhumans

• Use of punishment anything that decreases
  magnitude or frequency of a behavior. Does the
  drug decrease the effectiveness of punishment.
  Sedatives do amphetamines do not
• Drug discrimination paradigm teach animal to
  discriminate between the effects of a placebo and
  the effects of a particular drug
• Used to determine if a new drug has a similar
  effect as an older drug
• Also if the two drugs have the same effect on the
  actions of neurotransmitters

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Drug development and testing

• Major issue with psychoactive drugs
• 1. we know most mental disorders involve
  biochemical imbalances
• 2. we know that psychoactive drugs operate on
  the effect of neurotransmitter systems
• 3. we do not know exactly what the specific
  biochemical imbalance is in most disorders so it
  is difficult to know what drug will work with
  what disorder
• This results in extensive testing with nonhumans
• This results in extensive testing with nonhumans

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Nonhuman testing

• Purpose
• Identification of exactly which neurotransmitter
  system or systems the drug effects and identifies
  possible side effects
• Identification of effective versus toxic dosages
  based upon body weight looking for drugs with
  the largest difference between the two
• Obviously interspecies differences a problem

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Human testing

• Purpose
• Identify short-term and long-term effects in
  humans
• Detailed analysis of aversive effects never
  ending unless drug is discontinued