Embodied and disembodied allocentric simulation in high schizotypal subjects

Abstract

It is known that non-clinical subjects with high levels of schizotypal personality traits (High-S), as well as schizophrenic patients, have difficulties to judge how a scene would appear (so-called Appearance questions) from a point of view other than their own after having performed a disembodied perspective taking (D-PT, a mental self-rotation cued by an object like a chair). This inability has been defined allocentric simulation deficit. However, it is still unclear whether this inability might also regard an embodied transformation (E-PT), which is a self-rotation cued by another individual in the scene, and whether the observed deficit regards the pure mental transformation phase. In the present study, we took advantage of a virtual reality environment to explore both embodied and disembodied allocentric simulation in healthy volunteers with low and high levels of schizotypal personality traits, as assessed by the Schizotypal Personality Questionnaire. All subjects performed a pure self-rotation cued by a chair (D-PT) or by an avatar (E-PT), or a control array rotation. Each rotation was followed by classical Appearance and Item questions. Results revealed no between-groups differences in the mental transformation phase, while High-S subjects were significantly slower than Low-S subjects in the Appearance task after D-PT, but not after E-PT. Accordingly, higher schizotypy levels (cognitive-perceptual subscale) were positively correlated with slower reaction times in the Appearance task after D-PT. These data suggest the existence of a disembodied allocentric simulation deficit in non-clinical High-S, paving the way to future studies on clinical populations.

Mental rotation and schizotypal personality traits: A Bayesian approach

“…It is worth noting that the importance of the employed analytical approach could be decisive to draw conclusions. When literature is not consistent regarding the existence of a relationship between two variables, such as the case of schizotypy and mental rotation (e.g., Jha, Read, Hurd & Crespi, 2018; Steinisch et al ., 2011; Thakkar & Park, 2010; Vastano, Sulpizio, Steinisch, Comani & Committeri, 2014), the effect size should also be taken into account to ensure that the effect is not spurious or due to randomness. As explained above, the use of HDIs and ROPEs using a Bayesian approach may be useful for this purpose (Kruschke, 2011).…”

“…(2011) reported improved performance in both men and women with high global schizotypy that were also measured with the SPQ in an array and self‐mental rotation task. On the contrary, Vastano, Sulpizio, Steinisch, Comani and Committeri (2014) detected a negative relationship between mental rotation performance and Cognitive‐perceptual scores in the SPQ, while other studies (e.g., Jha, Read, Hurd & Crespi, 2018) have found spared – but neither enhanced nor impaired – mental rotation in people with high schizotypy. Thus, it can be concluded that more research is needed to better elucidate the relationship between schizotypy and mental rotation performance.…”

“…Since our goal was to detect subtle effects (Ettinger et al ., 2015) that might not appear if they were beneficial and the task was easy, or if they were impairing and the task was hard (as we could not presume the direction of a possible schizotypy‐mental rotation relationship), the use of a task that features two distinct difficulty levels, which most studies do not utilize, is required. Although the direction of this possible schizotypy‐mental rotation relationship cannot be presumed due to previous contradictory findings (Jha, Read, Hurd & Crespi, 2018; Steinisch et al ., 2011; Thakkar & Park, 2010; Vastano, Sulpizio, Steinisch, Comani & Committeri, 2014), it is expected to find sex differences in the mental rotation task, as this is a typical result in mental rotation paradigms (Boone & Hegarty, 2017).…”