Vocal Acoustic Correlates of Flat Affect in Schizophrenia: Similarity to Parkinson's Disease and Right Hemisphere Disease and Contrast with Depression

In a survey of authoritative psychiatric texts, inconsistent, sometimes contradictory use can be found of the terms ‘affect’, ‘mood’, and ‘emotion’. There is some consensus that these terms deal with subsets of the larger domain of feelings, but many authorities, explicitly or implicitly, treat them as at least partially interchangeable. Others see the terms as referring to different phenomena, but disagree on how they differ. In lay usage, feelings are primarily subjective experiences, but the term is used here in a more encompassing, generic sense. In the psychiatric texts, some attributes are frequently used to distinguish among feelings. These include the duration of the phenomena; whether they are subjective, objective or both; the relative involvement of cognition; and whether they are clinically observable or rather reflect the patient's potential for response. Some examples of current usage will be considered before alternative formulations are suggested.