Lab Experiment: Examples & Strengths (2023)

What do you think of when you hear the word "laboratory"? Do you picture people in white coats and goggles and gloves standing over a table with beakers and tubes? Well, that picture is pretty close to reality in some cases. In others, especially in psychology, laboratory experiments often look nothing like that!

  • We will start by looking at the lab experiment definition and how lab experiments are used in psychology.
  • Moving on from this, we will take a look at how lab experiment examples in psychology and how cognitive lab experiments may be conducted.
  • And to finish off, we will explore the strengths of lab experiments and weaknesses too.

Lab Experiment Psychology Definition

From the name, you can probably guess that lab experiments take place in well, lab settings. Although this is not always the case, they can sometimes occur in other controlled environments. The purpose of lab experiments is to identify the cause and effect of a phenomenon through experimentation.

A lab experiment is an experiment that uses a carefully controlled setting and standardised procedure to accurately measure how changes in the independent variable (IV; variable that changes) affects the dependent variable (DV; variable measured).

In lab experiments, the IV is what the researcher predicts as the cause of a phenomenon, and the dependent variable is what the researcher predicts as the effect of a phenomenon.

Lab Experiment: Psychology

Lab experiments in psychology are used when trying to establish causal relationships between variables.

A researcher would use a lab experiment if they were investigating how sleep affects memory recall.

The majority of psychologists think of psychology as a form of science. And, therefore they argue that the protocol used in psychology research should resemble those used in the natural sciences. For research to be established as scientific, three essential features should be considered:

  1. Empiricism - the findings should be observable via the five senses.
  2. Reliability - if the exact study was replicated, then similar results should be found.
  3. Validity - the investigation should accurately measure what it intends to.

But do lab experiments fulfil these requirements of natural sciences research? Actually, if done correctly, then yes. Lab experiments are empirical as they involve the researcher observing changes occurring in the DV.

Reliability is established by using a standardised procedure in lab experiments.

A standardised procedure is a protocol that states how the experiment will be carried out. This allows the researcher to ensure the same protocol is used for each participant, increasing the study's internal reliability.

Standardised procedures are also used to help other researchers replicate the study to identify if they measure similar results.

Dissimilar results reflect low reliability.

Validity is another feature of a lab experiment considered. Lab experiments are conducted in a carefully controlled setting where the researcher has the most control compared to other experiments to prevent extraneous variables from affecting the DV.

Extraneous variables are factors other than the IV that affect the DV; as these are variables that the researcher is not interested in investigating, these reduce the validity of the research.

There are issues of validity in lab experiments, which we'll get into a bit later!

Lab Experiment: Examples & Strengths (1)Scientists working in a lab,

Lab Experiment Examples: Asch's Conformity Study

The Asch (1951) conformity study is an example of a lab experiment. The investigation aimed to identify if the presence and influence of others would pressure participants to change their response to a straightforward question. Participants were given two pieces of paper, one depicting a 'target line' and another three, one of which resembled the 'target line' and the others of different lengths.

The participants were put in groups of eight. Unknown to the participants, the other seven were confederates (participants who were secretly part of the research team) who were instructed to give the wrong answer. If the actual participant changed their answer in response, this would be an example of conformity.

Asch controlled the location where the investigation took place, constructed a contrived scenario and even controlled the confederates who would affect the behaviour of the actual participants to measure the DV.

Some other famous research that is lab experiment examples includes research conducted by Milgram (the obedience study) and Loftus and Palmer's eyewitness testimony accuracy study. These researchers likely used this method because of some of their strengths, e.g., their high level of control.

Lab Experiment Examples: Cognitive Lab Experiments

Let's look at what a cognitive lab experiment may entail.

Suppose a researcher is interested in investigating how sleep affects memory scores using the MMSE test.

In the theoretical study, an equal number of participants were randomly allocated into two groups; sleep-deprived versus well-rested. Both groups completed the memory test after a whole night of sleep or staying awake all night.

In this research scenario, the DV can be identified as memory test scores and the IV as whether participants were sleep-deprived or well-rested.

Some examples of extraneous variables the study controlled include researchers ensuring participants did not fall asleep, the participants took the test during the same time of day, and participants in the well-rested group slept for the same amount of time.

Strengths of Lab Experiments

In the following, we will present the advantages of laboratory experiments. This discusses the controlled setting, standardised procedures and causal conclusions.

Strengths of Lab Experiments: Highly Controlled

Laboratory experiments are conducted in a well-controlled setting. All the variables, including extraneous and confounding variables, are rigidly controlled in the investigation. Therefore, the risk of experimental findings being affected by extraneous or confounding variables is reduced. As a result, the well-controlled design of laboratory experiments implies the research has high internal validity.

Internal validity means the study uses measures and protocols that measure exactly what it intends to, i.e. how only the changes in the IV affect the DV.

Strengths of Lab Experiments: Standardised Procedures

Laboratory experiments have standardised procedures, which means the experiments are replicable, and all participants are tested under the same conditions. Therefore, standardised procedures allow others to replicate the study to identify whether the research is reliable and that the findings are not a one-off result. As a result, the replicability of laboratory experiments allows researchers to verify the study's reliability.

Strengths of Lab Experiments: Causal Conclusions

A well-designed laboratory experiment can draw causal conclusions. Ideally, a laboratory experiment can rigidly control all the variables, including extraneous and confounding variables. Therefore, laboratory experiments provide great confidence to researchers that the IV causes any observed changes in DV.

Weaknesses of Lab Experiments

In the following, we will present the disadvantages of laboratory experiments. This discusses ecological validity and demand characteristics.

Weaknesses of Lab Experiments: Low Ecological Validity

Laboratory experiments have low ecological validity because they are conducted in an artificial study that does not reflect a real-life setting. As a result, findings generated in laboratory experiments can be difficult to generalise to real life due to the low mundane realism. Mundane realism reflects the extent to which lab experiment materials are similar to real-life events.

Weaknesses of Lab Experiments: Demand Characteristics

A disadvantage of laboratory experiments is that the research setting may lead to demand characteristics.

Demand characteristics mean the cues that make participants aware of what the experimenter expects to find or how participants are expected to behave.

The participants are aware they are involved in an experiment. So, participants may have some ideas of what is expected of them in the investigation, which may influence their behaviours. As a result, the demand characteristics presented in laboratory experiments can arguably change the research outcome, reducing the findings' validity.

Lab Experiment - Key takeaways

  • The lab experiment definition is an experiment that uses a carefully controlled setting and standardised procedure to establish how changes in the independent variable (IV; variable that changes) affects the dependent variable (DV; variable measured).

  • Psychologists aim to ensure that lab experiments are scientific and must be empirical, reliable and valid.

  • The advantages of lab experiments are high internal validity, standardised procedures and the ability to draw causal conclusions.

  • The disadvantages of lab experiments are low ecological validity and demand characteristics.

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