PSYCHIATRIC symptom rating scales can be used for testing and reformulating clinical concepts as well as for categorizing patients. Hallucinations and delusions are two symptoms that take on new meanings when defined more operationally for use in such scales. It is especially important to conceptualize these symptoms adequately because they are key diagnostic criteria of the psychoses, especially of schizophrenia. Even those who classify hallucinations and delusions as "secondary" tend to use these symptoms to establish the diagnosis of psychosis since they are among the easier symptoms to identify clinically. Generally hallucinations and delusions are considered to be discrete and discontinuous, a patient either has them or he does not. The notion of the discreteness of these symptoms encourages the conception of psychosis and schizophrenia as states that are also discrete and discontinuous and the further conception that patients with these diagnoses are somehow qualitatively different from other