There are three major research designs that psychologists use to analyze human behavior based on a given study. Descriptive research designs simply create an image of the state of affairs at a given moment. On the other hand, correlational designs make an assessment of the relationships between two or more variables while experimental designs make an assessment of the causal impact of certain experimental manipulations made on a dependent variable. Under the experimental designs, we can have an experimental group, which is the group that receives the tested variable, and the control variable, which is the group that does not receive the variable being tested. Let us analyze various hypotheses and classify them as either correlational or experimental designs:
Blondes have more fun
This study suggests that blondes (people with colored hair) tend to have more fun than people with hair of a normal color. This is a case of a correlational research design, where a blonde is the independent variable, while the amount of fun that they have is the dependent variable. This study cannot be run as an experiment because being blonde is just a matter of the hair color, something that an individual can change at any time.
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Children with no father influence are more aggressive
This study suggests that father influence is a crucial factor when it comes to how aggressive a child is. As such, a child who does not have any father influence tends to be more aggressive. This study is an experimental research design, where the experimental group is children with no father influence while the control group is children with father influence. The dependent variable that is being measured is the level of aggression.
Athletes are less aggressive
This study suggests that the level of aggression in an individual depends on whether they are athletes or not. The independent variable in this correlational research design is whether a person is an athlete or not, while the dependent variable is the level of aggression.
The lightest shade in the optic array will be perceived as white and all other colors will be anchored on that color.
This hypothesis presents an experimental study design, where different shades in an optic array are viewed in a different manner. The lightest shade in the array is considered the experimental group, while all the other colors act as the control groups.
Religious people are healthier than people who are not religious.
In this study, we see the suggestion that the level of health that an individual enjoys is dependent on whether they are religious or not. For this reason, the religious perspective of an individual is the independent variable while the level of health is the dependent variable.
The more walking a person does, the larger his or her calf muscles will be.
This study suggests that the size of human calf muscles is dependent on the amount of walking that the person does. Therefore, the amount of walking is the independent variable while the size of calf muscles is the dependent variable.
People talk to their friends more than strangers.
This study suggests that the amount of talking that an individual does with another person depends on the level of familiarity that exists between them. Therefore, the level of familiarity is the independent variable while the amount of talking is the dependent variable.
Watching television at close range causes poor eyesight.
This is an experimental study design that seeks to analyze the effect that the TV range has on someone’s eyesight. The control variable, in this case, is watching TV at a close range while the control variable is watching TV from a distance. In this case, the quality of eyesight is what is being tested, and it is the dependent variable.
Confounding and Extraneous Variables
Some of the hypotheses discussed above have extraneous and/or confounding variables. These include:
Children with no father influence are more aggressive
In this case, the study is testing whether father influence has an effect in the extent to which a child is aggressive. However, there are several other factors that affect the level of aggression in a child, for instance the environment in which they have grown. In this case, the environment serves as an extraneous variable.
The more walking a person does, the larger his or her calf muscles will be.
In this study, a person might not do a lot of walking, but they engage in vigorous exercise, and this would result in larger calf muscles. Therefore, the amount of exercise acts as confounding variable that was not targeted but it has an effect on the dependent variable.
