There were no significant differences between the total scores for patients with schizophrenia and the total scores for healthy volunteers receiving ketamine on the Scale for the Assessment of Thought, Language, and Communication (t=0.43, df=23, p=0.67, d=0.19). There was no significant difference between the groups’ scores on any of the factors tested on the Scale for the Assessment of Thought, Language, and Communication. The scores for the unidimensional severity factor (t=–0.40, df=23, p=0.69, d=0.18), the paired factors for verbal productivity (t=0.75, df=23, p=0.46, d=0.30) and disconnection (t=0.21, df=23, p=0.84, d=0.10), and the paired factors for positive (t=0.02, df=23, p=0.98, d=0.01) and negative (t=1.10, df=23, p=0.28, d=0.45) symptoms did not differ for the patients with schizophrenic thought disorder and the patients with ketamine-induced thought disorder. Only the scores for one of the 20 individual items on the Scale for the Assessment of Thought, Language, and Communication—perseveration (t=2.13, df=23, p=0.04)—differed significantly for the two groups. This item was not found to be significantly different after use of a Bonferroni correction for the 20 comparison items (F1). In patients with schizophrenia and healthy volunteers receiving ketamine, scores for three of the four highest rated items on the Scale for the Assessment of Thought, Language, and Communication—poverty of speech, circumstantiality, and loss of goal—were the same.