Identify IVs and DVs

1
Identify IV(s) and DV(s)

• In a cognitive mapping study, first-year students
  are compared with seniors in their ability to
  point accurately to campus buildings. Some of
  the buildings are on the periphery of the campus
  along well-traveled routes other buildings are
  on the periphery of campus. Participants are
  asked to indicate (on a scale of 1-10), how
  confident they are about their pointing, and the
  amount of error (in degrees) in their pointing is
  recorded.

2
Identify IV(s) and DV(s)

• In a study of the effectiveness of a new drug in
  treating depression, some patients receive the
  drug while others only think they are receiving
  it. A third group is not treated. After the
  program is completed, participants complete the
  Beck Depression Inventory and are rated on
  depression (10-point scale) by trained observers.

3
Identify IV(s) and DV(s)

• In a Pavlovian conditioning study, hungry animals
  are conditioned to salivate to the sound of a
  tone by pairing the tone with food For some
  animals, the tone is turned on and then off
  before the food is presented. For others, the
  tone remains on until the food is presented. For
  still others, the food precedes the tone.
  Experimenters record when salivation first begins
  and how much saliva accumulates for a fixed time
  interval.

4
Does this research involve a subject variable or
true IV?

• An experiment is investigating the effects of
  caffeine on memory
• An experiment is investigating memory in caffeine
  drinkers and non-drinkers
• An experiment is investigating whether tall
  people are likely to be extroverts

5
Does this research involve a subject variable or
true IV?

• An experiment is investigating whether nutrition
  aids alertness in the classroom
• An experiment is investigating how sleep affects
  judgment
• An experiment is investigating whether males and
  females differ in impulsivity

6
Identify some threats to the external validity

• An experimenter was interested in whether
  participants would prefer a small amount of food
  right away, or would choose a large amount of
  food they had to wait for. The experiment took
  place in the morning. The experimenter used
  peanut MMs as the food item. The experimenter
  recruited a group of adolescents to participate.
  Most of the participants preferred the small,
  immediate number of MMs to the larger, but
  delayed amount of MMs. The experimenter
  concluded that people were impulsive for food.

7
Identify some threats to the external validity

• An experimenter was interested in whether prefer
  small, immediate amounts of money to large,
  delayed amount of money. College students are
  recruited to participate. Students are given
  choices between 10,000 in 10 yrs vs. X amount
  right now (the value of X varied across trials).
  All monetary amounts were hypothetical. Students
  tended to prefer the large, delayed option until
  the immediate amount was very large.

8
Identify some threats to the external validity

• Female rats received diets containing low or
  standard amounts of protein for 5 weeks prior to
  mating and during pregnancy. All pups received
  adequate nutrition from birth onwards. At 91 days
  old the pups were tested on the Lashley jump
  stand in 3 visual discrimination problems. Rats
  whose mothers received insufficient protein made
  more errors overall and were slower to learn
  visual discrimination tasks involving a vertical-
  vs horizontal-stripe discrimination task. It
  appears that if a rat is malnourished during
  pregnancy, her offspring may face long-term
  visual deficits.

• Tonkiss, J., Galler, J. R., Shukitt-Hale, B.,
  Rocco, F. J. (1991). Prenatal protein
  malnutrition impairs visual discrimination
  learning in adult rats. Psychobiology, 19,
  247-250.

9
Find the confound

• A testing company is trying to determine if a new
  type of driver (club1) will drive a golf ball
  greater distances than three competing brands
  (clubs 2-4). Twenty male golf pros are recruited.
  Each golfer hits 50 balls with club 1, then 50
  more with 2, then 50 with 3, then 50 with 4. To
  add realism, the experiment takes place over the
  first four holes of an actual golf course the
  first set of 50 is hit from the first tee, the
  second 50 from the second tee, and so on. The
  first four holes are all 380-400 yards in length,
  and each is a par 4 hole.

10
Find the confound

• A social psychologist is interested in helping
  behavior and happens to know two male graduate
  students who would be happy to assist. The first
  (Ned) is well dressed, but the second (Ted)
  doesnt care much about appearances. An
  experiment is designed in which passerby in a
  mall will be approached by a student who is
  either well-dressed Ned or shabbily-dressed Ted.
  All the testing sessions occur between 8-9
  oclock in the evening, with Ned working on
  Monday and Ted working on Friday. The student
  will approach a shopper and ask for a quarter for
  a cup of coffee. Nearby, the experimenter will
  record whether or not people give money.

11
You are asked to evaluate the effectiveness of an
after-school program.

• 1. After reviewing some documentation, you learn
  that a test was administered both before and
  after the program. But the tests were different.
  Find the threat.
• a. History
• b. Mortality
• c. Testing
• d. Instrumentation

Developed by Paul Burns
12

• 2. About half way through your program, the three
  most at-risk students, and consequently the
  lowest scores on the pre-test, are arrested and
  subsequently leave the program. Find the threat!!
• a. Maturation
• b. Testing
• c. Mortality
• d. Compensatory Rivalry

Developed by Paul Burns
13

• 3. The program uses the only computers on
  campus. Other students want access as well so
  they tell there parents. Parents begin calling
  complaining. The principal therefore provides
  access other students during school hours.
• a. Diffusion of Treatment
• b. Compensatory Equalization of Treatment
• c. Mortality
• d. Compensatory Rivalry

Developed by Paul Burns
14

• 4. Since all of the students are at-risk and the
  primary criteria for participation in the program
  is poor academic performance, when assessing the
  effectiveness of the program based on pre and
  post test measures, you must be careful of what
  internal-validity threat?
• a. Mortality
• b. Regression
• c. Testing
• d. Diffusion of Treatment

Developed by Paul Burns
15

• 5. The program is one year project. Over the
  course of the program the students are students
  naturally developing and growing and increasing
  their knowledge of the world. Find the threat.
• a. Regression
• b. Mortality
• c. Maturation
• d. Resentful Demoralization

Developed by Paul Burns
16
Examples and Non-examples if Internal Validity
Threats

• An experimenter is investigating the effects of
  gun-safety training on a childs willingness to
  pick up a gun. The study is conducted with a
  class of 3rd and 4th graders. The experimental
  manipulation is for the experimental group to get
  gun-safety training by a police officer. The
  control group will receive no training.
  Afterwards, children will be tested in a
  simulated environment in which they come across a
  misplaced gun. What they do with the gun will
  be recorded.

Credits to Athabasca University, Psychology
Dept.
17
In which case is Selection a threat?

• The experimenter puts all of the 3rd graders in
  the experimental group and gives them gun-safety
  training. All of the 4th graders are put in the
  control group. The experiment shows that those
  in the control group pick up the gun more than
  those in the experimental group.
• The experimenter puts all of the childrens name
  into a hat and pulls out equal numbers for the
  gun training and control groups. The experiment
  shows that those in the control group pick up the
  gun more than those in the experimental group.

Credits to Athabasca University, Psychology
Dept.
18
In which case is History a threat ?

• Children are randomly selected for the
  experimental and control group. The children in
  the experimental group are tested first. Before
  the children in the control group are tested, a
  case of an gun injury by a child is reported in
  the news. The experiment shows no difference
  across groups - few children in either group pick
  up the gun.
• Children are randomly selected for the
  experimental and control group. The children in
  the experimental group are tested at the same
  time. Before the experiment begins, a case of an
  gun injury by a child is reported in the news.
  The experiment shows no difference across groups
  - few children in either group pick up the gun.

Credits to Athabasca University, Psychology
Dept.
19
In which case is Maturation a threat ?

• Children are randomly selected for the
  experimental and control group. The police
  officer gives gun-safety training to the
  experimental group, and both groups are tested 1
  week later. The experiment shows no difference
  across groups - few children in either group pick
  up the gun.
• Children are randomly selected for the
  experimental and control group. First, children
  in the control group are tested. The officer who
  is supposed to do the training, however, is
  unable to come to the school. Nine months later
  the experimental group is given the training and
  are tested. The experiment shows no difference
  across groups - few children in either group pick
  up the gun.

Credits to Athabasca University, Psychology
Dept.
20
In which case is Testing a threat ?

• Children are randomly selected for the
  experimental and control group. All children are
  tested. The police officer gives gun-safety
  training to the experimental group, and both
  groups are tested again. The experiment shows no
  difference across groups - few children in either
  group pick up the gun.
• Children are randomly selected for the
  experimental and control group. The police
  officer gives gun-safety training to the
  experimental group, and both groups are tested.
  The experiment shows no difference across groups
  - few children in either group pick up the gun.

Credits to Athabasca University, Psychology
Dept.
21
In which case is Mortality a threat ?

• Children are randomly selected for the
  experimental and control group. The police
  officer gives gun-safety training to the
  experimental group, but some children are too
  disruptive and are removed. Children in both
  groups are then tested. The experiment shows that
  few children in the experimental group pick up
  guns, but that many children in the control group
  do.
• Children are randomly selected for the
  experimental and control group. The police
  officer gives gun-safety training to the
  experimental group and traffic-safety training to
  the control group. In both groups, children that
  are too disruptive are removed. Children in both
  groups are then tested. The experiment shows that
  few children in the experimental group pick up
  guns, but that many children in the control group
  do.

Credits to Athabasca University, Psychology
Dept.
22
In which case is Experimental Bias a threat ?

• Children are randomly selected for the
  experimental and control group. The police
  officer gives gun-safety training to the
  experimental group. Children in both groups are
  tested. During testing, an observer who doesnt
  know what group the children are in (i.e., a
  blind observer) records the behavior of the
  children. The experiment shows an effect of
  training.
• Children are randomly selected for the
  experimental and control group. The police
  officer gives gun-safety training to the
  experimental group. Children in both groups are
  tested. During testing, the experimenter, who
  believes the training will decrease gun handling,
  records the behavior of the children. The
  experiment shows an effect of training.

Credits to Athabasca University, Psychology
Dept.
23
Identify some threats to the internal validity

• A study is designed to test the effects of a drug
  on aggressive behavior. First, two rats are put
  together in a testing chamber to measure
  aggression. Those who win the fight are
  selected for the experimental group. A second
  group of inexperienced rats is used as the
  control group. Both groups are tested again in
  an aggression test but the experimental group is
  given a drug. The rats in the experimental group
  are more aggressive than rats in the control
  group, suggesting that the drug increases
  aggression.

24
Identify some threats to the internal validity

• A group of investigators were interested in how
  warning signs of the danger of skin cancer posted
  by a pool would affect sunblock use. The
  experimenters recruited the lifeguards of the
  pool to record the data. The experimenters told
  the lifeguards about the study and asked the
  lifeguards to walk around with a clipboard and
  record the total number of times they saw people
  putting on sunblock. The next day, the
  experimenters put up the signs. The lifeguards
  for that day were asked to record sunblock use.
  Sun block use increased that day. The researchers
  reported that the signs were effective in
  increasing sunblock use.

25
Identify some threats to the internal validity

• A study is designed to test whether newborns
  prefer to hear their parents voices over the
  voices of strangers. At 7 days old, infants are
  tested with their mothers voice and a strange
  females voice. Two weeks later, infants are
  tested with their fathers voice and a strange
  males voice. The study shows that infants
  prefer their fathers voice over a strange males
  voice much more than their mothers voice over a
  strange females voice

26
Social validity

• You are interested in implementing a weight loss
  program. You decide to implement a
  self-management program whereby each person
  charts their own calories consumed and exercise
  time. Your plan is to have participants make
  graduate changes in calories/exercise across
  weeks. What are some of your social validity
  concerns?
• Goals Procedures Outcomes
• Subjective evaluation? Social comparison?

27
Social validity

• You are working with a restaurant to increase
  sanitation among employees. You decide to use
  managers to record behavior of employees across a
  shift, chart and display the behavior, and
  delivery monetary bonuses to employees with the
  best performance. What are some of your social
  validity concerns?
• Goals Procedures Outcomes

Subjective evaluation? Social comparison?