TABLE 2.

Example of the Categorization for the Index Finger

Friction at the index finger contact	No. of other fingers at low friction contact
	0	1	2	3
High friction at the thumb contact
H	HHHHH	HHLHH	HHLLH	HHLLL
		HHHLH	HHHLL
		HHHHL	HHLHL
L	HLHHH	HLLHH	HLLLH	HLLLL
		HLHLH	HLHLL
		HLHHL	HLLHL
Low friction at the thumb contact
H	LHHHH	LHLHH	LHLLH	LHLLL
		LHHLH	LHHLL
		LHHHL	LHLHL
L	LLHHH	LLLHH	LLLLH	LLLLL
		LLHLH	LLHLL
		LLHHL	LLLHL

Note. The data of 32 surface conditions for each finger were categorized by (a) surface at the thumb contact (high-friction contact [H] or low-friction contact [L]), (b) surface at the finger contact (H or L), and (c) number of other fingers at low-friction contact (from 0 to 3)—in total 16 groups. The groups are presented in the individual cells in the four right-hand columns of the table. For instance, the comparison was performed for the groups HHLHH, HHHLH, HHHHL and for the groups HLLHH, HLHLH, HLHHL. Similar categorizations and similar analyses were performed for the middle, ring, and little fingers.