Which research method allows specific variables to be controlled and manipulated?
Experimental MethodBy Dr. Saul McLeod, published 2012 Show
The experimental method involves the manipulation of variables to establish cause and effect relationships. The key features are controlled methods and the random allocation of participants into controlled and experimental groups. An experiment is an investigation in which a hypothesis is scientifically tested. In an experiment, an independent variable (the cause) is manipulated and the dependent variable (the effect) is measured; any extraneous variables are controlled. An advantage is that experiments should be objective. The views and opinions of the researcher should not affect the results of a study. This is good as it makes the data more valid, and less biased. There are three types of experiments you need to know: 1. Lab ExperimentA laboratory experiment is an experiment conducted under highly controlled conditions (not necessarily a laboratory), where accurate measurements are possible. The researcher decides where the experiment will take place, at what time, with which participants, in what circumstances and using a standardized procedure. Participants are randomly allocated to each independent variable group. An example is Milgram’s experiment on obedience or Loftus and Palmer's car crash study.
2. Field ExperimentField experiments are done in the everyday (i.e. real life) environment of the participants. The experimenter still manipulates the independent variable, but in a real-life setting (so cannot really control extraneous variables). An example is Holfing’s hospital study on obedience.
3. Natural ExperimentNatural experiments are conducted in the everyday (i.e. real life) environment of the participants, but here the experimenter has no control over the independent variable as it occurs naturally in real life. For example, Hodges and Tizard's attachment research (1989) compared the long term development of children who have been adopted, fostered or returned to their mothers with a control group of children who had spent all their lives in their biological families.
Key TerminologyEcological validityThe degree to which an investigation represents real-life experiences. Experimenter effectsThese are the ways that the experimenter can accidentally influence the participant through their appearance or behavior. Demand characteristicsThe clues in an experiment that lead the participants to think they know what the researcher is looking for (e.g. experimenter’s body language). Independent variable (IV)Variable the experimenter manipulates (i.e. changes) – assumed to have a direct effect on the dependent variable.
Dependent variable (DV)Variable the experimenter measures. This is the outcome (i.e. result) of a study. Extraneous variables (EV)All variables, which are not the independent variable, but could affect the results (DV) of the experiment. EVs should be controlled where possible. Confounding variablesVariable(s) that have affected the results (DV), apart from the IV. A confounding variable could be an extraneous variable that has not been controlled. Random AllocationRandomly allocating participants to independent variable conditions means that all participants should have an equal chance of taking part in each condition. The principle of random allocation is to avoid bias in the way the experiment is carried out and to limit the effects of participant variables. Order effectsChanges in participants’ performance due to their repeating the same or similar test more than once. Examples of order effects include: (i) practice effect: an improvement in performance on a task due to repetition, for example, because of familiarity with the task; (ii) fatigue effect: a decrease in performance of a task due to repetition, for example, because of boredom or tiredness. How to reference this article:How to reference this article:McLeod, S. A. (2012, January 14). Experimental method. Simply Psychology. www.simplypsychology.org/experimental-method.html How to reference this article:How to reference this article:McLeod, S. A. (2012, January 14). Experimental method. Simply Psychology. www.simplypsychology.org/experimental-method.html Home | About Us | Privacy Policy | Advertise | Contact Us Simply Psychology's content is for informational and educational purposes only. Our website is not intended to be a substitute for professional medical advice, diagnosis, or treatment. © Simply Scholar Ltd - All rights reserved What type of research allows the researcher to control and manipulate the variables?Experimental research allows the researcher to control the situation. In so doing, it allows researchers to answer the question, “What causes something to occur?” Permits the researcher to identify cause and effect relationships between variables and to distinguish placebo effects from treatment effects.
What is variable manipulation in research?Again, to manipulate an independent variable means to change its level systematically so that different groups of participants are exposed to different levels of that variable, or the same group of participants is exposed to different levels at different times.
Which research method manipulating a variable in a controlled situation in order to understand the effect it has on the dependent variable?In the experimental method of research, the independent variable is manipulated to observe and measure its effect on the dependent variable. Experimental Method: Experimental research is research conducted with a scientific approach using two sets of variables.
In which type of research is there control randomization and manipulation?Section 2: Experimental Studies
True experiments have four elements: manipulation, control , random assignment, and random selection. The most important of these elements are manipulation and control.
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