Objective tests are measures in which responses maximize objectivity, in the sense that response options are structured such that examinees have only a limited set of options (e.g. Likert scale, true or false).
[1] These ‘projective tests’ require examinees to generate unstructured responses to ambiguous tasks or activities, the content of which is supposed to represent their personal characteristics (e.g. internal attitudes, personality traits).
[1][3] Although the fixed response style of objective tests does not require interpretation on the part of the examiner during the administration and scoring of the measure, responses to questions are subject to the examinee's own response style and biases, in much the same way they are for projective measures; therefore, both test ‘types’ are vulnerable to subjective factors that may affect scores.
[4] Furthermore, understanding and giving meaning to the results of any assessment, projective and objective alike, is done within the context of an examinee's personal history, presenting concerns, and the myriad of factors that can affect examinee's scores on the assessment.
Thus, both objective and projective tests carry potential sources of bias and require judgment in interpretation to varying degrees.