Figure 1.

Graphical surface of the consistency test and examples of consistency test results for different patients. (A) Participants selected a color for each item presented on the screen by moving a cross-hair cursor over a color matrix. The majority of patients reported not perceiving colors when seeing numbers or letters and made inconsistent color choices as in (B). Accordingly, those patients have rather high scores in the consistency test (>1.0). This is consistent with their reports and their low scores in the six-point questionnaire (<17). Three patients made consistent color choices (score <1.0) for letters and numbers (C) or numbers only (D) which was consistent with their reports and six-point questionnaire scores (those patients claiming to perceive synesthesia differently for numbers and letters completed the questionnaire twice, separately for numbers and letters).