Research Design Problems For the following problems: Identify the type of investigation used (i.e., non-experimental, experimental, or quasi- experimental) If the investigation has an independent variable, dependent variable, and/or extraneous variable, identify each. 1. A researcher decides to examine the effect of playing violent video games on aggressive behavior in aircraft maintainers. These maintainers were randomly assigned to one of two groups. Group A consisted of 20 who spent 30 minutes playing a violent video game: Borg Death Fighters. Group B consisted of 20 who spent 30 minutes playing a nonviolent video game: Baseball Two-D. Following the time spent playing the video game, the maintainers all played in the same room with others. A BoBo doll with a bat was available in order to express any aggressive actions. The number of aggressive acts and aggressive verbalizations by each maintainer was recorded. Those in Group A exhibited a significantly greater number of aggressive behaviors on both measures. The researcher concluded that playing violent video games may lead to aggressive behavior in maintainers. a. Type of investigation? b. Variables? 2. A researcher examines the effects on reaction times of Air Traffic Controllers taking a minimum of 45 minutes exercise each day. Subjects recorded the length and time spent exercising on a daily basis. After two weeks, subjects turned in their daily exercise logs to the researcher and reaction time measures were taken. Clearly, participants who exercised more had the better the reaction times. The researcher concludes that exercise leads to better reaction time. a. Type of investigation? b. Variables? 3. A researcher tested the effect of caffeine on sleep. Forty pilots volunteered to participate in the study and signed up for one of two nights. Pilots on Tuesday night drank a cup of regular coffee and those on Wednesday night received a cup of decaffeinated coffee. They then took a nap and length of time to fall asleep was recorded with the aid of an EEG. Pilots in the caffeine group took significantly longer to fall asleep. The researcher concludes that caffeine interferes with the ability to fall asleep. a. Type of investigation? b. Variables? 4. A researcher tests the effect of listening to instrumental music on learning of material in a statistics book. Subjects (college students) are randomly assigned to groups and all tested during one testing session. Group A wears headphones and listens to instrumental music Page 1 of 2 and Group B wears headphones but no music is being played. The music is the same for all subjects in Groups A. Each are given an equal amount of time to study and then tested over the material. Group A performs significantly poorer. The students participating in the study are unaware of the hypothesis and the person scoring the examinees is unaware of which group the subjects were in. The researcher concludes that listening to instrumental music may be detrimental to learning. a. Type of investigation? b. Variables? Page 2 of 2