Experiments: Practice identifying independent and dependent variables

[sue_frantz]

Psychology students often struggle with the difference between the independent and dependent variables. After covering these concepts, ask students to work in pairs or small groups to identify both the independent variable(s) and the dependent variable(s) in each example.

Hypothesis: Creating concrete examples will improve recall.

"Students read a short text that introduced eight concepts. Some students were then prompted to generate concrete examples of each concept followed by definition restudy, whereas others only restudied definitions for the same amount of time. Two days later, students completed final tests involving example generation and definition cued recall." (In the definition cued recall test, the cues were the names of each of the concepts; the "recall" was the student writing down the definition.) Those who created their own examples of each of the concepts did better on the test than students who just restudied the concepts. 

In this experiment, identify the independent variable and the dependent variable. 

Rawson, K. A., & Dunlosky, J. (2016). How effective is example generation for learning declarative concepts? Educational Psychology Review, 28(3), 649–672. https://doi.org/10.1007/s10648-016-9377-z

Hypothesis: Attending to a phone will decrease the likelihood of seeing a unicycling clown.

People, after walking across a college square, were asked if they saw a clown unicycling around a central sculpture. Only 25% of cell phone users reported seeing the clown as compared to 60% of people who were listening to music, 51% of people who were walking alone with no technological distractions, and 71% of people who were walking with another person.

This type of study is called a quasi-experiment because participants weren't randomly assigned to conditions.

In this experiment, identify the independent variable and the dependent variable. 

Hyman, I. E., Boss, S. M., Wise, B. M., McKenzie, K. E., & Caggiano, J. M. (2010). Did you see the unicycling clown? Inattentional blindness while walking and talking on a cell phone. Applied Cognitive Psychology, 24, 597–607. https://doi.org/10.1002/acp.1638

Hypothesis: Being sleep-deprived will increase the desire for high-calorie foods.

After either get a full night’s sleep or staying awake all night, participants were asked how desirable each of 80 different foods were.  When participants were sleep-deprived, they found high-calorie foods more desirable than when they had a full night’s sleep.

This type study is called a within-subjects design because the same participants got both the full night’s sleep and, on another night, stayed awake all night.

In this experiment, identify the independent variable and the dependent variable. 

Greer, S. M., Goldstein, A. N., & Walker, M. P. (2013). The impact of sleep deprivation on food desire in the human brain. Nature Communications, 4, 1–7. https://doi.org/10.1038/ncomms3259

Hypothesis: “Inflated praise [will] decrease challenge-seeking in children with low self-esteem but [will] increase challenge-seeking in children with high self-esteem.”

Children (ages 8 to 12), after having their self-esteem measured, “drew a famous painting… and were told that that a professional painter, who in reality did not exist, would examine their drawing.”  Each child then received a handwritten note that they were told was written by the painter. The note said either, “You made an incredibly beautiful drawing!,” “You made a beautiful drawing!,” or did not address the drawing. Children then could choose to replicate two easy drawings (“If you choose to draw these easy pictures, you won’t make many mistakes, but you won’t learn much either.”) or two difficult drawings (“If you choose to draw thsese difficult pictures, you might make many mistakes, but you’ll definitely learn a lot, too.”). Children with low self-esteem who received the incredibly beautiful praise were more likely to choose the easy drawings. Children with low self-esteem who received the beautiful praise were likely to choose the difficult drawings. Those results were reversed for children with low self-esteem.

In this experiment, identify the two independent variables and the dependent variable.

Brummelman, E., Thomaes, S., Orobio de Castro, B., Overbeek, G., & Bushman, B. J. (2014). “That’s not just beautiful-that’s incredibly beautiful!”: The adverse impact of inflated praise on children with low self-esteem. Psychological Science, 25(3), 728–735. https://doi.org/10.1177/0956797613514251

Hypothesis: Tasters will rate vinegar-laced beer as better than regular beer if they are not first told that vinegar has been added to the beer.

Participants were invited to taste two different beers and express their preference for one over the other. Participants were told that the beer was laced with vinegar either before or after tasting or were told nothing. Participants who weren’t told that the beer was laced with vinegar or were told after they tasted it preferred it over the regular beer. Those who were told it was laced with vinegar before tasting it preferred the regular beer.

In this experiment, identify the independent variable and the dependent variable.

Lee, L., Frederick, S., & Ariely, D. (2006). Try it, you’ll like it: The influence of expectation, consumption, and revelation on preferences for beer. Psychological Science, 17(12), 1054–1058. https://doi.org/10.1111/j.1467-9280.2006.01829.x