Experimental Methods In Psychology

February 6, 2025 – Paper 2 Psychology in Context | Research Methods

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When conducting research in psychology, a psychologist has to consider what method they are going to use in order to collect their data. A psychologists has two choices, they can either use an Experimental Method to collect their data or, they can use a Non-Experimental Method to collect their data. There are three Experimental Methods in the field of psychology; Laboratory, Field and Natural Experiments. Each of the Experimental Methods holds different characteristics in relation to; the manipulation of the IV, the control of the EVs and the ability to accurately replicate the study in exactly the same way.

Method	Description of Method	Strengths	Weaknesses
Laboratory Experiment	A highly controlled, artificial setting in which the experimenter is able to manipulate the Independent Variable (IV) and control for Extraneous Variables (EVs) preventing them from becoming Confounding Variables which would lower Internal Validity. Examples of Laboratory Experiments include: Loftus and Palmer Leading Questions Study Asch’s Conformity Study	(+) A strength of a Laboratory Experiment is that the researcher has a high level of control. Experimenters are able to control the Independent Variable (IV) and the potential Extraneous Variables (EVs) that may affect the overall results of the study. This is a strength because, by exercising this level of control, researchers are able to establish a cause and effect relationship between the Independent Variable and the Dependent Variable, as a result, the study will have high internal validity. (+) A second strength of using a Laboratory Experiment is, due to the high level of control, laboratory experiments can be replicated in exactly the same way under exactly the same conditions. This is a strength as it means that the reliability of the research can be assessed (i.e. a reliable study will produce the same findings over and over again).	(-) A weakness of a Laboratory Experiment is that it has Low Ecological Validity. A laboratory experiment takes place in an unnatural, artificial setting. As a result participants may behave in an unnatural manner. This is a weakness because it means that the experiment may not be measuring real-life behaviour. (-) Another weakness of a laboratory experiment is that there is a high chance of demand characteristics. For example, as the laboratory setting makes participants aware they are taking part in research, this may cause them to change their behaviour in some way. For example, a participant in a memory experiment might deliberately remember less in one experimental condition if they think that is what the experimenter expects them to do to avoid ruining the results. This is a problem because it means that the results do not reflect real-life results as they are responding to demand characteristics and not just the independent variable.
Field Experiment	An experiment conducted in a real life setting where an experimenter can control the IV however the experimenter doesn’t have control over EVs (e.g. weather, background noise, individual participant differences etc…) For example, research looking at altruistic behaviour had a stooge (actor) stage a collapse in a subway and recorded how many passers-by stopped to help.	(+) A strength of a Field Experiment is that it has high ecological validity. Due to the fact that a field experiment takes place in a real-life setting, participants are unaware that they are being watched and therefore are more likely to act naturally. This is a strength because it means that the participants behaviour will be reflective of their real-life behaviour. (+) Another strength of a field experiment is that there are less chance of demand characteristics occurring. For example, because the research consists of a real life task in a natural environment it’s unlikely that participants will change their behaviour in response to demand characteristics/what they think the experimenter is looking for as part of the research study. This is positive because it means that the results reflect real-life as they are not responding to demand characteristics, just the independent variable.	(-) A weakness of a Field Experiment is that there is a low degree of control over variables. For example, extraneous variables such as the weather (if a study is taking place outdoors), noise levels or temperature are more difficult to control if the study is taking place outside the laboratory. This is problematic because there is a greater chance of extraneous variables affecting participant’s behaviour which reduces the experiments *internal validity* and makes a cause and effect relationship difficult to establish. (-) Another weakness of a Field Experiment is that they are very difficult to replicate. For example, if a study is taking place outdoors, the weather might change between studies and affect the participants’ behaviour. This is a problem because it reduces the chances of the same results being found time and time again and therefore can reduce the reliability of the experiment.
Natural Experiment	An experiment set in a real-life setting· The experimenter has no control over EVs or the IV as the IV is naturally occurring· Examples of Natural Experiments include, looking at the changes in levels of aggression after the introduction of the television. The introduction of the TV is the natural occurring IV and the DV is the changes in aggression (comparing aggression levels before and after the introduction of the TV).	The strengths of a Natural Experiment are exactly the same as the strengths of the field experiment: (+) Firstly, a Natural Experiment has high ecological validity due to the fact that the research is taking place in a natural setting and therefore is reflective of real-life natural behaviour. (+)Another strength of a Natural Experiment is that there is a low chance of demand characteristics. Due to the fact that the participants do not know that they are taking part in a study they will not change their behaviour and act unnaturally therefore the experiment can be said to be measuring real-life natural behaviour.	The *weaknesses* of a Natural Experiment are exactly the same as the strengths of the field experiment: (-)Firstly, a Natural Experiment has low control over variables. For example, the researcher isn’t able to control EVs and the IV is naturally occurring. This means that a cause and effect relationship cannot be established and there is low internal validity. (-) A second weakness is due to the fact that there are no control over variables, a natural experiment cannot be replicated and therefore reliability is difficult to assess for.

When conducting research, it is important to create an aim and a hypothesis, click here to learn more about the formation of aims and hypotheses.

In addition, when carrying out research there are many design elements that researchers need to consider before conducting their research including; having an awareness of and dealing with potential ethical issues, sampling methods, and, when conducting a Laboratory Experiment, a researcher needs to decide when Experimental Design they are going to use. Learn more about these design features by clicking the title hyperlinks.

Some researchers decide to conduct Non-Experimental methods as opposed to Experimental Methods when conducting research. Non-Experimental Methods include; Naturalistic Observations, Questionnaires, Interviews and Case Studies.