Controlling extraneous variables

This document discusses extraneous variables that need to be controlled in experiments to avoid confounding results. It describes four types of extraneous variables: physical, social, personality, and context variables. For each variable, it provides examples of how they can influence experiments and methods for controlling them, such as eliminating variables, using single-blind or double-blind experiments, cover stories, and balancing conditions across treatments. The goal is to establish constancy of conditions and control for demand characteristics, experimenter bias, and other unintended influences on experimental outcomes.