Table 1. Dependent variables with definitions.

SCORED PER TRIAL
Success	Stick inserted into the cut-out (three-dimensional task), or aligned with the contour (two-dimensional task)
Above Tray Action	Stick moved horizontally above the tray or disc before making contact, with close visual attention to the stick and the tray or disk below
Number of Attempts	Each attempt was a particular combination of the hand, angle of the stick with respect to the horizontal plane, alignment of each feature of the stick to the matching cut-out or contour and movement of the stick on the tray or disc. A change in any one of these features constituted the end of one attempt and the start of a new attempt. A break of ½ second or longer in contact with the tray or disc also ended an attempt.
SCORED PER ATTEMPT
Position of Shaft (Long Feature)	Alignment to the long feature of the cut-out or contour, scored categorically in 45° octants using a clock-face rubric, where 12–6 indicated correct alignment and incorrect positions were scored as 3–9 (perpendicular), or 1–7 or 10–4 (intermediate between aligned and perpendicular octants)
Position of Cross Feature	Aligned (cross feature of the stick closer to the matching cross feature on the cut-out or contour) or Not aligned (closer to the end of the stick opposite the matching end)
Position of Tomahawk Head	Matching (the left-right orientation of the tomahawk feature on the cut-out or contour) or Not matching (reversed orientation)
Angle	Angle of the long axis of the stick with respect to the tray or disc upon contact: 90 if within 10° of 90°, 0 if within 10° of 0°, 45 if between these positions
Surface Assistance	Scored in 3D trials only. Moving the stick across the boundary between the tray’s flat surface and the cut-out