Fig. 3: Response surface analysis (RSA) of the interactive association of positive schizotypy and AQ attention to detail with left and right tail hippocampal cerebral blood flow (CBF in ml/100 mg/min).

The blue lines are the balance and bias axes, where the balance axis represents equal expressions of autistic and positive schizotypy traits, and the bias axis (orthogonal to the balance axis) represents the relative and progressive dominance of autistic and/or positive schizotypy traits. Figures show a curvilinear relationship between these traits and hippocampal volumes, with volumes being smaller along the bias axis and particularly in individuals with either positive schizotypy-dominant or an AQ attention to detail-dominant trait profile, and larger in individuals with relatively balanced levels of positive schizotypy and AQ attention to detail, and particularly in individuals with either low-low or high-high trait profiles. However, this curvilinearity was only significant for the association of the balance axis with CBF of the left hippocampal tail (Left: β(se) = 2.44 (0.81), 95%CI= (0.85, 4.03), p = 0.003; Right: β(se) = −3.24 (1.93), 95%CI = (−7.02, 0.55), p = .094). Surface colour-coding represents the CBF of the hippocampus from low (green) to high (red).