Question

Why are Likert scales written so half of the responses, agreeing with them means the person has the variable measured, whereas the other half, agreeing with the item means that the person does not have the variable being measured?

Answer 1

They are written in this manner in order to to reduce the influence of acquiescent bias (responding).

Step-by-step explanation:

Acquiescence bias (responding) is a category of response bias in which respondents to a survey have a tendency to agree with all the questions or to indicate a positive connotation. Acquiescence is sometimes referred to as "yea-saying" and is the tendency of a respondent to agree with a statement when in doubt.

By formating the Likert scale so that in one half agreeing with means that the person has the variables measured and the other half means that the variable is not measured avoides acquiescent bias (responding).