Table 1. Mean percentages of correct responses and mean response time data in eight pretest sessions for each stimulus orientation condition and each individual.

	% correct				Response time (ms)
	Upright		Inverted		Upright		Inverted
Monkeys	Mean	S.D.	Mean	S.D.	Mean	S.D.	Mean	S.D.
Heiji	87.4	8.6	70.7	9.1	1370.8	388.7	1415.3	366.1
Kiki	91.5	5.4	72.3	9.2	1398.5	248.8	1284.0	221.6
Pigmon	89.2	7.4	73.0	10.2	1474.8	407.0	1378.6	305.3
Zilla	91.7	7.4	65.2	14.0	1351.6	306.0	1330.6	306.3