This study is the first to report findings of schizophrenia patients on the TASIT, a videotape measure of ToM that assesses the ability to draw inferences about the intentions, beliefs, and feelings of others in social interactions involving counterfactual statements (i.e., lies vs. sarcasm). The primary finding was that schizophrenia vs. control group differences were largely accounted for by differences in the ability to comprehend sarcasm. Compared with demographically comparable healthy adults, schizophrenia participants showed greater difficulty comprehending sarcasm than lies. This finding was present with the full schizophrenia sample as well as a subset with low level positive symptoms. Hence, the relative discrepancy in the ability to comprehend sarcasm does not appear to be an artifact of psychotic symptoms.
Our findings are consistent with the lone previous report on sarcasm involving a schizophrenia sample (Leitman et al. 2006
). In that study, inpatients and outpatients with schizophrenia or schizoaffective disorder were compared with a healthy control group. The ability to detect sarcasm was assessed using the attitudinal subtest from the Aprosodia Battery (Orbelo et al. 2005
) that included an audiotape presentation of 10 semantically neutral sentences (e.g., “This looks like a safe boat.”) recorded by a female speaker in both a sincere and a sarcastic tone of voice. Participants’ task was to ascertain whether the speaker was being sarcastic or sincere. Though the methods used in the Leitman et al. study were considerably different than those used in the present one, the results provide convergent evidence for a deficit in this area of processing.
We can only speculate about the reasons for impairment in the perception of sarcasm but not lies in persons with schizophrenia. Leitman et al. (2006)
proposed that the observed deficits in sarcasm might be due to difficulties in the processing of physical features that give rise to the percept of sarcasm (i.e., alterations in stress and prosody) rather than a more general ToM deficit. In line with this possible explanation, it is noteworthy that the physical cues that “tip off” the observer about whether someone is telling a white lie or being sarcastic are present only for the latter. For example, persons typically show little change in expression when telling a white lie in an attempt to conceal the deception. In contrast, persons making a sarcastic remark often present with exaggerated facial expression, voice tone, and gestures for effect. In the TASIT Part III scenes, the determination of white lies places fewer demands on information processing. Social cues are less relevant and the determination can be made by viewing the camera shot or prologue/epilogue that reveals the true state of affairs to one of the characters but not the other. For the sarcasm scenes, this supplemental information is helpful but not sufficient to make an accurate determination. The viewer must attend to and accurately process subtle changes in paralinguistic and other social cues from the characters’ conversational exchange in addition to information from the camera shot or prologue/epilogue. The findings from the present study suggest that persons with schizophrenia may not be impaired in ToM globally, but only certain areas with greater information processing load or perhaps, those ToM areas more intimately tied to the ability to perceive facial expression and paralinguistic cues. Interestingly, impaired perception of sarcasm but not lies was also found in the lone study with TBI patients using the TASIT (McDonald et al., 2003
Despite the observed differences in comprehension of sarcasm vs. lies in the present study, care should be taken in interpreting these findings as definitive of a differential deficit. Testing for a differential deficit requires measures to be equated on true score reliability, variance, and level of difficulty (Chapman & Chapman, 1978
). For the present study, no a priori efforts were made to ensure that the two conditions were equated on these psychometric properties. However, interpretation of findings should also consider two other sources of information, the TASIT’s administration methods and healthy adult data from the present study. It would be difficult to argue that schizophrenia participant difficulties on sarcasm vs. lies were due to differences in the methods used to assess these conditions. For both sarcasm and lies, the structure of the scenes was highly similar (e.g., characters, settings, length of video clip), and the type of questions and response format were the same. Post hoc examination of subscale scores for sarcasm vs. lies in the healthy adult group revealed highly comparable levels of performance accuracy and variance for both types of scenes, levels comparable with published norms for this test (McDonald et al. 2006
). Hence, even though the measures were not deliberately manipulated for the purpose of testing a differential deficit, they were fairly well matched.
Examination of the relationship between TASIT performance and community functioning yielded negative findings. Of 18 comparisons, one trend finding emerged and the significance of that relationship disappeared after consideration of positive symptoms. In hindsight, it is not clear that we should expect one. Despite the substantial number of studies documenting the presence of ToM deficits in schizophrenia, few have examined the relationship between ToM and community functioning. A recent review (Couture et al. 2006
) revealed four published reports of ToM and functional outcome in schizophrenia; only one examined community functioning and the findings were mixed (Roncone et al., 2002
). Perhaps, ToM is less directly tied to broader community functioning that can be influenced by a number of variables (e.g., family support, employment opportunities, social environment) and instead, is more closely related to narrower areas within interpersonal functioning such as social communication. For example, it might be expected that the ability to “read” other persons’ mental states would be necessary to communicate effectively, and this ability may in turn facilitate the formation and maintenance of social relationships, though the latter could be influenced by other variables as well. There is some, albeit limited, evidence to support this notion (McCabe et al., 2004
Our findings indicated a significant relationship between ToM ability and positive, but not negative symptoms. Specifically, TASIT performance was related to SAPS subscales measuring severity of delusions and positive formal thought disorder, as well as overall positive symptom severity. In contrast, TASIT performance did not show a significant relationship with overall severity of negative symptoms or any of the negative symptom subscales. The findings for negative symptoms are generally consistent with those reported by Leitman et al. (2006)
that also used the SANS. However, that study did not find a significant relationship between sarcasm and positive symptoms, perhaps because they used a different measure (BPRS vs. SAPS). In general, reviews of the literature have yielded mixed findings for a relationship between ToM and positive and negative symptoms. The inconsistencies across studies may be due to differences in the samples, the measures used to assess symptom severity, the area of ToM assessed (e.g., first-and second-order false beliefs, sarcasm, irony), and the ToM measures used.
The study is limited by the lack of inclusion of other measures of ToM to evaluate how comprehension of sarcasm and lies compares with other ToM abilities such as understanding first- and second-order false beliefs, metaphors, jokes, empathy, or adult faux pas. Also, a broad-based neurocognitive battery was not administered, so we cannot make claims about the independence of observed group effects on this measure relative to differences in general cognitive functioning. The schizophrenia sample was comprised of stable chronic outpatients and we do not know if these findings may extend to more acute patients or those early in the course of their illness.
In sum, this report is the first to our knowledge to use videotape recordings of social interactions to assess ToM in schizophrenia. In terms of ecological validity, the TASIT has advantages over paper-and-pencil measures and more closely captures the kinds of ToM processes involved in daily interactions with others in everyday conversations. This study showed a differential impairment in the ability to perceive sarcasm vs. lies for persons with schizophrenia. Though intriguing, this finding requires replication in other independent studies using the TASIT or similar measures.