Patients with schizophrenia are biased toward low spatial frequency to decode facial expression at a glance

Whereas patients with schizophrenia exhibit early visual processing impairments, their capacity at integrating visual information at various spatial scales, from low to high spatial frequencies, remains untested. This question is particularly acute given that, in ecological conditions of viewing, spatial frequency bands are naturally integrated to form a coherent percept. Here, 19 patients with schizophrenia and 16 healthy controls performed a rapid emotion recognition task with hybrid faces. Because these stimuli displayed in a single image two different facial expressions, in low (LSF) and high (HSF) spatial frequencies, the selected emotion probes which spatial scale is preferentially perceived. In a control experiment participants performed the same task with either low or high spatial frequency filtered faces. Results show that patients have a strong bias towards LSF with hybrid faces compared to healthy controls. However, both patients and healthy controls performed better with HSF filtered faces than with LSF filtered faces in the control experiment, demonstrating that the bias found with hybrid stimuli in patients was not due to an inability to process HSF. Whereas previous works found a LSF contrast deficit in schizophrenia, our results suggest a deficit in the normal time course of concurrently perceiving LSF and HSF. This early visual processing impairment is likely to contribute to the difficulties of patients with schizophrenia with facial processing and therefore social interaction.