Double blind control expectation – UGC NET Question

A double-blind design ensures that both participants and the researchers who have contact with them are unaware of which individuals are in the experimental or control group. This reduces expectancy effects, such as participants changing behaviour because they think they are receiving a special treatment, and experimenter bias, where researchers unintentionally influence outcomes. By keeping group assignment concealed from both parties, the design enhances the credibility of observed differences. Therefore, the arrangement described in the stem is correctly called double-blind.

Option A:
Single-blind designs keep group assignment hidden from participants but not from researchers, so experimenter expectations can still influence data collection or interpretation. This makes single-blind less effective than double-blind in controlling expectancy effects, so it does not fully match the stem.

Option B:
Open-label studies are those in which both participants and researchers know who receives the treatment, making them vulnerable to numerous biases. They are not designed to control expectancy effects and therefore are not an appropriate completion.

Option C:
Option C, double-blind, is widely used in clinical trials and psychological experiments to address both participant and experimenter expectations simultaneously. This dual masking corresponds exactly to the description in the question, making it the correct option.

Option D:
Matched-pairs designs pair participants based on similarity in key characteristics before assigning them to different conditions but do not inherently prevent either party from knowing group assignments. Thus, matched-pairs is not the right answer here.