“…PPI deficits have been observed across the schizophrenia spectrum in some (but not all) medicated and unmedicated patients (Anokhin, Heath, Myers, Ralano, & Wood, ; Braff et al, ; Greenwood et al, ), in relatives of patients, and in patients diagnosed with schizotypy (Cadenhead, Swerdlow, Shafer, Diaz, & Braff, ; Kumari, Das, Zachariah, Ettinger, & Sharma, ). Although hundreds of studies have looked at PPI and its deficiency in clinical conditions, PPI deficits are generally only weakly correlated with schizophrenic symptomatology (Hasenkamp et al, ; Molina et al, ; Swerdlow et al, ). This may be due to a heterogeneous patient population, or to variations in methodology across studies.…”