Lets Say We Decided to Run the Experiment Again This Time We Used

Chapter 6: Experimental Research

Conducting Experiments

1. Draw several strategies for recruiting participants for an experiment.
2. Explain why it is important to standardize the procedure of an experiment and several ways to exercise this.
3. Explain what pilot testing is and why information technology is of import.

The information presented so far in this chapter is plenty to design a basic experiment. When it comes fourth dimension to conduct that experiment, nevertheless, several additional practical issues arise. In this section, we consider some of these issues and how to deal with them. Much of this information applies to nonexperimental studies as well as experimental ones.

Recruiting Participants

Of course,at the beginning of whatever research projecty'all should be thinking about how you will obtain your participants. Unless you have access to people with schizophrenia or incarcerated juvenile offenders, for example, then there is no point designing a written report that focuses on these populations. But fifty-fifty if you plan to use a convenience sample, you lot volition have to recruit participants for your report.

There are several approaches to recruiting participants. One is to use participants from a formal —an established group of people who have agreed to be contacted about participating in research studies. For example, at many colleges and universities, there is a subject pool consisting of students enrolled in introductory psychology courses who must participate in a certain number of studies to meet a grade requirement. Researchers post descriptions of their studies and students sign upward to participate, usually via an online system. Participants who are non in subject pools can also be recruited by posting or publishing advertisements or making personal appeals to groups that correspond the population of interest. For example, a researcher interested in studying older adults could arrange to speak at a meeting of the residents at a retirement community to explain the study and ask for volunteers.

"Written report."The affiche reads: Volunteers needed for a scientific study investigating whether people tin can distinguish between scientific studies and kidney-harvesting scams. (Good for you Blazon-O Adults But).

Even if the participants in a report receive bounty in the class of course credit, a small amount of coin, or a chance at beingness treated for a psychological trouble, they are notwithstanding essentially volunteers. This is worth because because people who volunteer to participate in psychological inquiry accept been shown to differ in predictable ways from those who do not volunteer. Specifically, there is good testify that on average, volunteers have the following characteristics compared with nonvolunteers (Rosenthal & Rosnow, 1976)^[ane]:

• They are more interested in the topic of the enquiry.
• They are more than educated.
• They have a greater need for approval.
• They take higher intelligence quotients (IQs).
• They are more than sociable.
• They are higher in social grade.

This deviation can be an consequence of external validity if there is reason to believe that participants with these characteristics are likely to behave differently than the general population. For instance, in testing different methods of persuading people, a rational argument might work better on volunteers than it does on the full general population considering of their generally higher educational level and IQ.

In many field experiments, the task is non recruiting participants but selecting them. For case, researchers Nicolas Guéguen and Marie-Agnès de Gail conducted a field experiment on the consequence of being smiled at on helping, in which the participants were shoppers at a supermarket. A confederate walking down a stairway gazed directly at a shopper walking upward the stairway and either smiled or did not smiling. Shortly afterward, the shopper encountered another confederate, who dropped some computer diskettes on the ground. The dependent variable was whether or non the shopper stopped to help pick up the diskettes (Guéguen & de Gail, 2003) ^[two]. Notice that these participants were non "recruited," but the researchers notwithstanding had to select them from among all the shoppers taking the stairs that day. It is extremely of import that this kind of selection be done co-ordinate to a well-defined set of rules that is established earlier the data collection begins and can be explained clearly afterward. In this case, with each trip down the stairs, the confederate was instructed to gaze at the starting time person he encountered who appeared to exist between the ages of 20 and 50. Only if the person gazed back did he or she become a participant in the report. The point of having a well-defined option rule is to avert bias in the pick of participants. For example, if the confederate was complimentary to cull which shoppers he would gaze at, he might cull friendly-looking shoppers when he was prepare to smile and unfriendly-looking ones when he was non set to smile. As we volition see soon, such biases tin can be entirely unintentional.

Standardizing the Procedure

Information technology is surprisingly like shooting fish in a barrel to introduce extraneous variables during the procedure. For example, the same experimenter might give clear instructions to one participant but vague instructions to another. Or i experimenter might greet participants warmly while another barely makes eye contact with them. To the extent that such variables affect participants' behaviour, they add racket to the data and brand the result of the independent variable more difficult to detect. If they vary beyond weather condition, they go confounding variables and provide alternative explanations for the results. For example, if participants in a treatment group are tested by a warm and friendly experimenter and participants in a control grouping are tested by a cold and unfriendly one, then what appears to be an effect of the treatment might really be an effect of experimenter demeanor. When in that location are multiple experimenters, the possibility for introducing inapplicable variables is even greater, but is oftentimes necessary for practical reasons.

It is well known that whether enquiry participants are male or female person can affect the results of a written report. But what nigh whether the experimenter  is male or female? At that place is plenty of testify that this matters too. Male and female experimenters have slightly unlike means of interacting with their participants, and of course participants also respond differently to male and female experimenters (Rosenthal, 1976) ^[3].

For example, in a contempo study on pain perception, participants immersed their hands in icy water for as long as they could (Ibolya, Restriction, & Voss, 2004) ^[4]. Male person participants tolerated the hurting longer when the experimenter was a woman, and female participants tolerated information technology longer when the experimenter was a man.

Researcher Robert Rosenthal has spent much of his career showing that this kind of unintended variation in the process does, in fact, affect participants' behaviour. Furthermore, one important source of such variation is the experimenter's expectations about how participants "should" behave in the experiment. This effect is referred to equally an  (Rosenthal, 1976) ^[5].For instance, if an experimenter expects participants in a treatment group to perform better on a task than participants in a control group, then he or she might unintentionally give the treatment group participants clearer instructions or more than encouragement or allow them more fourth dimension to consummate the chore. In a striking case, Rosenthal and Kermit Fode had several students in a laboratory grade in psychology train rats to run through a maze. Although the rats were genetically similar, some of the students were told that they were working with "maze-brilliant" rats that had been bred to exist proficient learners, and other students were told that they were working with "maze-wearisome" rats that had been bred to be poor learners. Sure enough, over five days of training, the "maze-bright" rats made more correct responses, fabricated the correct response more apace, and improved more than steadily than the "maze-dull" rats (Rosenthal & Fode, 1963) ^[6]. Clearly it had to have been the students' expectations near how the rats would perform that made the difference. But how? Some clues come up from data gathered at the stop of the report, which showed that students who expected their rats to learn rapidly felt more positively well-nigh their animals and reported behaving toward them in a more than friendly fashion (e.g., handling them more than).

The way to minimize unintended variation in the procedure is to standardize it as much as possible so that it is carried out in the same mode for all participants regardless of the condition they are in. Here are several ways to practice this:

• Create a written protocol that specifies everything that the experimenters are to do and say from the time they greet participants to the time they dismiss them.
• Create standard instructions that participants read themselves or that are read to them word for word past the experimenter.
• Automate the residual of the procedure every bit much as possible by using software packages for this purpose or even simple reckoner slide shows.
• Anticipate participants' questions and either enhance and answer them in the instructions or develop standard answers for them.
• Train multiple experimenters on the protocol together and have them practice on each other.
• Be certain that each experimenter tests participants in all conditions.

Some other good practice is to adapt for the experimenters to be "blind" to the research question or to the condition that each participant is tested in. The idea is to minimize experimenter expectancy furnishings past minimizing the experimenters' expectations. For example, in a drug study in which each participant receives the drug or a placebo, it is often the case that neither the participants nor the experimenter who interacts with the participants know which condition he or she has been assigned to. Because both the participants and the experimenters are bullheaded to the status, this technique is referred to every bit a . (A single-blind study is one in which the participant, but non the experimenter, is blind to the condition.) Of course, there are many times this blinding is not possible. For example, if you are both the investigator and the simply experimenter, it is non possible for yous to remain bullheaded to the research question. Also, in many studies the experimenter must  know the status because he or she must bear out the procedure in a dissimilar style in the different weather condition.

Placebo effect blocker. [Image Description]

Tape Keeping

It is essential to go along skilful records when you lot bear an experiment. Every bit discussed earlier, information technology is typical for experimenters to generate a written sequence of weather before the study begins then to test each new participant in the next condition in the sequence. As you lot test them, it is a good thought to add to this list basic demographic information; the date, time, and place of testing; and the proper name of the experimenter who did the testing. Information technology is also a skilful thought to have a place for the experimenter to write downwardly comments about unusual occurrences (e.g., a confused or uncooperative participant) or questions that come upward. This kind of data can be useful later if you decide to analy z e sex differences or furnishings of different experimenters, or if a question arises about a particular participant or testing session.

It can besides be useful to assign an identification number to each participant as you test them. Merely numbering them consecutively beginning with 1 is usually sufficient. This number tin can then also be written on any response sheets or questionnaires that participants generate, making it easier to continue them together.

Pilot Testing

It is ever a expert idea to conduct a  of your experiment. A pilot examination is a small study conducted to make sure that a new procedure works every bit planned. In a pilot test, you tin can recruit participants formally (e.g., from an established participant pool) or you can recruit them informally from among family, friends, classmates, and so on. The number of participants can be small, but it should be enough to give you confidence that your process works every bit planned. There are several of import questions that you tin reply by conducting a airplane pilot test:

• Do participants sympathise the instructions?
• What kind of misunderstandings do participants accept, what kind of mistakes do they make, and what kind of questions do they enquire?
• Practice participants become bored or frustrated?
• Is an indirect manipulation effective? (You will need to include a manipulation bank check.)
• Tin can participants guess the research question or hypothesis?
• How long does the procedure take?
• Are figurer programs or other automated procedures working properly?
• Are data being recorded correctly?

Of grade, to answer some of these questions you lot will demand to find participants advisedly during the procedure and talk with them about information technology afterward. Participants are often hesitant to criticize a study in front of the researcher, and so be sure they empathize that their participation is part of a pilot examination and y'all are genuinely interested in feedback that volition aid you meliorate the procedure. If the procedure works equally planned, then y'all tin can continue with the actual study. If there are problems to exist solved, you can solve them, airplane pilot examination the new procedure, and keep with this procedure until you are gear up to proceed.

• There are several effective methods you can utilise to recruit inquiry participants for your experiment, including through formal subject pools, advertisements, and personal appeals. Field experiments crave well-defined participant selection procedures.
• It is important to standardize experimental procedures to minimize inapplicable variables, including experimenter expectancy effects.
• Information technology is important to deport one or more pocket-size-scale pilot tests of an experiment to be sure that the process works as planned.

1. Practice: List two means that you might recruit participants from each of the post-obit populations:
   1. elderly adults
   2. unemployed people
   3. regular exercisers
   4. math majors
2. Discussion: Imagine a study in which you will visually present participants with a list of 20 words, i at a fourth dimension, wait for a brusque fourth dimension, and then ask them to call back as many of the words as they tin can. In the stressed status, they are told that they might likewise exist chosen to requite a short voice communication in front of a small audience. In the unstressed condition, they are non told that they might take to give a oral communication. What are several specific things that you could do to standardize the process?

Image Descriptions

A comic of ii stick figures talking.

Person ane: Some researchers are starting to figure out the mechanism backside the placebo effect. Nosotros've used their work to create a new drug: A placebo effect blocker. Now nosotros just need to run a trial. Nosotros'll go two groups, give them both placebos, then requite one the REAL placebo blocker, and the other a…. wait.

[The two people scratch their heads]

Person 2: My caput hurts.

Person 1: Mine too. Here, want a carbohydrate pill?

[Return to Image]

Media Attributions

• Study by XKCD CC By-NC (Attribution NonCommercial)
• Placebo blocker by XKCD CC Past-NC (Attribution NonCommercial)

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Source: https://opentextbc.ca/researchmethods/chapter/conducting-experiments/

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