Everyday Research Methods

How much do chimpanzees cooperate?

Which behaviors were used to operationalize cooperation in chimps?
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Human beings are a fundamentally prosocial and cooperative species, but what about one of our close relatives, the chimpanzee?  A science writer summarized a series of studies on chimpanzees who live in the Tchimpounga Chimpanzee Sanctuary, in the Republic of the Congo. The summary is here and you can read the empirical journal article here.

The studies illustrate how researchers can operationalize a variable like "cooperativeness" in other species. It provides a clear example of observational research, too. 

Researcher Alexandra Rosati conducted three observational tasks on the sanctuary, all meant to operationalize the construct cooperativeness. The first task took place with chimp volunteers who were alone in a dormitory area. One experimenter grabbed another one's stick and threw it out of reach into the dormitory. The second researcher made a show of trying to get the stick back through the bars of the dormitory. Would the chimp help her out by bringing her the stick? The researcher conducted 10 trials with each chimp. You can see the task in action at this link--watch Video 2. The journalist writes:

On average, the chimpanzees, who received no reward for cooperating, chose to hand the out-of-reach object to the researcher just over 50% of the time – but the rate of cooperation varied significantly among the individuals, with some helping in all 10 trials and others not at all. Chimps who chose to help more often also chose to help more quickly, supporting the conclusion that more cooperative individuals tend to make decisions faster than more selfish individuals do, the authors wrote.

Notice that there are two findings here. The first is the simple result of how many chimps helped (that's a frequency claim result).The second result is a correlational pattern. 

a.) What is the frequency claim you can make here? 

b.) Reread the description of the "stick" study (above) and decide what two variables are correlated.

c.) Placing these two variables on the x and y axis, sketch a scatterplot of the result that is described. (Compare your sketch to Figure 2a in the empirical journal article.) 

d.) Comment on the operationalization of the construct "Cooperation". Why might the researchers have chosen this operationalization? 

Here's a second way they studied chimp cooperation. This operationalization asks whether the chimps would punish individuals who don't follow rules:

When they had an opportunity to punish a thief who stole food from them, the chimps often chose to collapse the experimenter’s table [by pulling out the table's false leg] to prevent the thief from consuming the ill-gotten treats. 

e.) You can watch the "stealing" task here, under Video 3. What behavior (by the chimps) was used to operationalize "cooperativeness" here?  Why might this behavior be considered as an operationalization of Cooperation?

Finally, another task used in the study presented chimpanzees with two options for food. This task is viewable in Video 1 here: 

When presented with two sets of plates, one that contained a snack for both the chimpanzee and a familiar caretaker and another that had a treat only for the chimp, the apes were basically indifferent to whether the experimenter got something to eat. 

f.) The three operationalizations of cooperation in chimps found variable results. Two operationalizations showed some "cooperation," and one apparently did not. What does this pattern of results suggest to you about the importance of how well we operationalize variables? 

 

 

Reading vs. listening

Photo: Ladida/Getty Images

Audiobooks are more popular than ever. Have you ever wondered if there are cognitive differences between reading print books and listening to audiobooks? In this editorial, psychologist Dan Willingham explains some of the research comparing the two formats. Dr. Willingham describes several research findings, most of which come from experimental designs. 

Here's one point Willingham makes: 

...there are differences between print and audio, notably prosody. That’s the pitch, tempo and stress of spoken words. “What a great party” can be a sincere compliment or sarcastic put-down, but they look identical on the page. Although writing lacks symbols for prosody, experienced readers infer it as they go. In one experiment, subjects listened to a recording of someone’s voice who either spoke quickly or slowly. Next, everyone silently read the same text, purportedly written by the person whose voice they had just heard. Those hearing the quick talker read the text faster than those hearing the slow talker.

a. In the study above, what is the independent variable?  Was it manipulated independent groups or within groups (and what keywords in the description help you decide?)

b. What is the dependent variable? 

c. Sketch a small graph of the results described, labeling your axes mindfully.

 

Here is another study from Willingham's summary:

It sounds as if comprehension should be easier when listening than reading, but that’s not always true. For example, one study compared how well students learned about a scientific subject from a 22-minute podcast versus a printed article. Although students spent equivalent time with each format, on a written quiz two days later the readers scored 81 percent and the listeners 59 percent.

d. In this study, what is the independent variable?  Was it manipulated independent groups or within groups (and what aspects if the description helped you decide?)

e. What is the dependent variable? 

f. Sketch a small graph of the results described, labeling your axes mindfully.

g. Do you think you could have conducted this study as a repeated-measures design? Why or why not? 

h. What questions do you have about the internal validity of this study? 

 

Suggested answers

a. The IV is reading speed of the narrator during the first task; its levels are Slow and Fast. The phrase, "either spoke quickly or slowly" tells you this was manipulated as independent groups.

b. The dependent variable was how fast people read the text passage. 

d. Here the IV is reading a text or listening to a podcast. The results phrase refers to "readers" and "listeners," implying that the IV was manipulated as between groups (independent groups).

e. The DV is score on a comprehension quiz.

g. It might be difficult to conduct this exact study as a repeated-measures design, because people would have to process the same content aurally and via reading. Once they've processed the content once, it would undoubtedly be easier to process it a second time. 

h. You'd want to be sure that i) people were randomly assigned to the two conditions. This would control for selection threats; and ii) people in the two conditions read or listened to the exact same text (for example, a podcast and its transcript). This would help avoid a design confound.