In psychological research, what does a "single-blind study" help to eliminate?

A "single-blind study" is a research design in which the participants do not know whether they are receiving the treatment or a control, such as a placebo. This design primarily helps to eliminate participant bias, which occurs when participants have preconceived notions about the treatment or expectations affect their behavior and responses during the study.

By keeping participants unaware of their treatment allocation, researchers can minimize the influence of these biases on the results, leading to more objective and valid data regarding the effectiveness of the intervention being tested. This can significantly enhance the reliability of the findings, as participants' behaviors and reactions are less likely to be influenced by their expectations.

In contrast, experimenter bias refers to the researcher’s expectations or beliefs inadvertently influencing the study's outcome, which isn't addressed by a single-blind study. Sample and response biases are also not directly controlled by this design as they pertain to the selection of participants and the delivery of responses, respectively. Thus, the single-blind method effectively mitigates participant bias, making it a valuable approach in psychological research.