In the early points in time of quantification of attributes in psychology progresses back to the days of Francis Galton who endeavoured to examine intelligence.
Extraneous variables are of three types:
? Situational variables: these are facets of the natural natural surroundings that might sway the participant's demeanor, for demonstration, disturbance, room heat, and lighting conditions. It is plausible that such variables have result on both the unaligned and reliant variables. These are to be controlled to encompass them at the very comparable point for topics and that they are unchanging without fluctuations.