Electrophysiological Correlates of Visual Backward Masking in Schizotypy

Visual deficits are well documented in schizophrenia. For example, a Vernier is followed by a blank inter-stimulus interval (ISI) and then a grating mask. Observers indicate the direction of the Vernier offset (left vs right). Patients need ISIs that are 120ms longer than in healthy controls (Herzog et al. 2004). Interestingly, these masking deficits are reflected in strongly reduced EEG amplitudes in schizophrenia patients when compared to healthy controls (Plomp et al. 2013). Schizophrenia is considered to be on a continuum ranging from strongly affected patients to healthy people with schizotypic personality traits. Schizotypic traits are measured with self report questionnaires such as the sO-LIFE (Mason et al. 2005). In analogy to patients, schizotypic traits are divided in positive traits (e.g., hallucinations), negative traits (e.g., anhedonia) and cognitive disorganization (CogDis). It has been shown that healthy students scoring high in CogDis show higher masking deficits than students scoring low in CogDis. On average, high CogDis students need ISIs that are 20ms longer than in low CogDis students (Cappe et al. 2012).