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Dog research has gotten much more popular in the last 10 years, as researchers study what cognitive and social abilities dogs have. Here's a study that tested whether dogs could tell the difference between a competent and an incompetent human. Here's how the study was summarized by by a dog blogger.
So, the gist of the experiment is that randomly-selected pet dogs watched two people manipulate a box. One person, the “competent” person, opened it easily. The other person, the “incompetent” person, did not.
Then, the researchers put a treat in the boxes.
The male dogs in the study asked the competent and incompetent people for the treats pretty equally [I imagine it's about 50-50].
The female dogs?
A whopping 83 percent of the time, the females asked the person they witnessed to be competent.
a) In the passage above, identify the manipulated IV and its levels.
b) How was this IV manipulated--as independent groups or within groups?
c) What was the DV in this study?
d) Dog's gender is another variable in this study--it's a PV, or participant variable. Is this an independent groups or within groups variable?
Because this study has an IV with two levels and a PV with two levels, it is a 2x2 factorial design.
e) Fill in this 2x2 table with the data mentioned above:
| Male dog | Female dog | |
| Competent | ||
| Incompetent |
f) Compute the marginal means for the IV and the PV, and estimate any main effects.
Describe main effects with this format:
"There is/is not a main effect for _[IV name]_ such that _[IV level]_ is higher on [DV] than _[IV level]_"
"There is/is not a main effect for _[PV name]_ such that _[PV level]_ is higher on [DV] than _[PV level]_"
g) Sketch a small line or bar graph of the results. Remember to put the DV on the y axis.
h) There is an interaction in these data. See if you can describe it!
Instructors: This would be a good example with which to have students compare popular press coverage to the original article. The empirical article is published in an Elsevier journal, which makes it harder to obtain for most people, but ILL can help. The blogger and Yahoo! newsboth make errors in reporting the study--for example, the dogs were not randomly selected, and there were about 60 dogs in the study, not 30 (they left out one of the conditions).
