Comparison of scoring methods for tests of attention, including an error index for use with schizophrenic patients

A resume is given of various doubts raised concerning the application of signal-detection theory to discrimination tasks involving 'supra-threshold' stimuli, as in tests of vigilance and selective attention. The validity of this theory in pathological conditions, such as schizophrenia, is also questioned. The continuing need for a unitary index combining errors or omission and commission is emphasized and the various indices so far proposed are compared using experimental data. A new Error Index is offered as a more satisfactory resolution.