Which phenomenon arises when the observer's data reporting is influenced by awareness that others are evaluating the data?

• A. Observer drift
• B. Observer reactivity
• C. Social desirability
• D. Reactivity bias

Answer: (D)

The main idea here is that measurement can become biased when the person collecting or reporting data knows that others are watching or evaluating it. That awareness can lead the observer to alter what they record—either tightening how they code behaviors, omitting ambiguous events, or otherwise shaping the data to look more favorable. This tendency is called reactivity bias: a systematic distortion in data reporting caused by the observer’s perception that they are under evaluation. It matters because the resulting data don’t reflect true occurrences, even when the same procedures are used.

Social desirability involves participants giving responses they think are acceptable, not the observer’s reporting. Observer drift would mean the scoring criteria change over time independently of being watched, and observer reactivity describes the general effect of being observed on the observer, but the specific bias in reported data due to that awareness is best described as reactivity bias.