The author used a scale that emphasizes objective behavioral signs to
evaluate affective flattening and to rate affect in 69 patients suffering
from schizophrenia (N = 30), mania (N = 19), and depression (N = 20).
Raters were blind to the patient's diagnosis. Interrater reliability was
assessed and found to be adequate to good for most items on the scale and
for a global rating. The affective flattening was found to be common, but
not omnipresent, in schizophrenia; it was also common among the depressed
patients. The author recommends that affective flattening be considered as
an important criterion for schizophrenia and that future research explore
its frequency and prognostic significance.