The neurocognitive underpinnings of diminished expressivity in schizotypy: What the voice reveals

Diminished expressivity is a characteristic feature of schizophrenia-spectrum pathology. However, attempts to elucidate the neurobiological underpinnings of diminished expressivity have yielded limited information. The present study posited that diminished expressivity was associated with a right, but not left-hemispheric dysfunction. Diminished expressivity was measured in separate groups of controls and psychometrically-identified individuals with schizotypic traits using 1) acoustic analysis of natural speech during a controlled laboratory procedure, and 2) self-report of expressivity. A state measure of emotional experience was also employed. For the most part, the schizotypy and control groups performed similarly on the neurocognitive measures. Within the schizotypy group diminished expressivity, measured using acoustic analysis, was significantly correlated with right hemispheric but not left hemispheric deficits. Conversely, the self-report measures of emotional expressivity and experience were relatively unrelated to the neurocognitive measures. These results highlight the role of the right hemisphere in diminished expressivity and support the use of acoustic analysis of speech as a sensitive means for researching diminished expressivity. The discussion focuses on placing the present findings in the larger context of understanding the neuropathology of schizophrenia-spectrum disorders.