Setup procedures for each method.
A. i. Subject positioning for the adaptive staircase method. Right hand placed on a 25° stand beneath the display screen. ii. The blindfolded subject was instructed to press firmly against the experimenter’s finger (dashed outline) and then relax to control for muscle thixotropy. iii. The hand was positioned in an outline drawn on the angled stand. The MP joint of the 2nd finger was on a tactile marker with the index finger pointing along a 55° line and the other fingers slightly spread. iv. The display screen was placed over the subject’s hand and the blindfold removed. Subject was asked, “Do you feel like the end of the white line is to the left or to the right of your index fingertip?” B. i. Subject positioning for the matching method. Both hands placed in outlines on the angle board, inclined at 25°. Subject blindfolded throughout. ii. Controlling for muscle thixotropy in both index fingers. iii. The experimenter (dashed outlines) moved each index finger in turn with a variety of motions. iv. The experimenter placed the right index finger along the 55° line and the left in a variety of positions about the mirrored position. Subjects were instructed to “Move your left index finger so it mirrors your right index finger.” C. i. Subject positioning for the PMDD method. Right hand on the left half of the angle board, inclined at 25°. Index finger taped to a smooth stick. Subjects blindfolded throughout. ii. Controlling for muscle thixotropy. iii. Experimenter placed hand with fingers slightly spread and index finger in a neutral position. iv. Touching only the stick, experimenter moved subject’s index finger right or left (~0.062°/s) to a standard angular magnitude. Subject was asked, “Did I move your finger to the left or to the right?”