Extraneous variables can have several effects on experimental research:
1. Confounding: Extraneous variables can become confounding variables when they are related to both the independent and dependent variables. This can lead to a distorted or misleading interpretation of the results, as it becomes difficult to determine whether the observed effect is due to the independent variable or the extraneous variable.
2. Bias: Extraneous variables can introduce bias into the study, affecting the accuracy and validity of the results. For example, if participants in one group of an experiment are more motivated or have different characteristics than participants in another group, the extraneous variable of motivation or participant characteristics can influence the outcome.
3. Reduced internal validity: Extraneous variables can decrease the internal validity of an experiment, which refers to the extent to which the observed effects can be attributed to the independent variable. If extraneous variables are not controlled or accounted for, they can introduce alternative explanations for the results, making it difficult to draw accurate conclusions about the relationship between the independent and dependent variables.
4. Decreased generalizability: Extraneous variables can also affect the generalizability or external validity of the research findings. If extraneous variables are not controlled, the results may only be applicable to the specific conditions of the study and may not be representative of the broader population or real-world situations.
To minimize the impact of extraneous variables, researchers employ various strategies such as randomization, matching, and statistical techniques like analysis of covariance (ANCOVA) to control for their effects.