Table 6.

Global and local switch costs in terms of drift rate for each participant group and for each discrimination task.

Groups	Global SC			Local SC			ANOVA				Contrast Tests
	M	SE	99% CI	M	SE	99% CI	Effect	F ratio	df	Partial ƞ2	GC	Global SC	Local SC
Letter Discrimination Task
College Students	−0.07	0.01	[−0.09, −0.05]	−0.01	0.01	[−0.02, 0.0]	G	7.09**	2	0.00	1	t(64.2) = −1.6	t(80.7) = −2.7**
61–74 year olds	−0.09	0.01	[−0.12, −0.07]	−0.03	0.01	[−0.05, −0.02]	T	22.17**	1	0.17	2	t(31.4) = −1.7	t(42.8) = −2.1*
75–89 year olds	−0.10	0.01	[−0.13, −0.07]	−0.03	0.01	[−0.05, −0.01]	C	69.94**	1	0.39	3	t(45.0) = −0.3	t(46.4) = 0.3
Brightness Discrimination Task
College Students	−0.04	0.01	[−0.05, −0.02]	−0.03	0.01	[−0.04, −0.02]	G × T	2.27	2	0.04	1	t(60.3) = −1.1	t(83.2) = 0.2
61–74 year olds	−0.05	0.01	[−0.07, −0.03]	−0.03	0.01	[−0.04, −0.02]	G × C	0.60	2	0.01	2	t(30.1) = −1.5	t(34.7) = 0.3
75–89 year olds	−0.06	0.01	[−0.08, −0.03]	−0.03	0.01	[−0.05, −0.01]	C × T	24.80**	1	0.19	3	t(45.8) = −0.5	t(36.5) = 0.1
							G × C × T	0.34	2	0.01

Note. SC = Switch Costs; Global SC = performance difference between pure and no-switch trials. Local SC = performance difference between no-switch and switch trials; ANOVA = analysis of variance; G = group; T = task type; C = switch cost type; CI = confidence interval; GC = group comparisons (1 = college students vs. 61–74 year olds; 2 = college students vs. 75–89 year olds; 3 = 61–74 year olds vs. 75–89 year olds).

^*p < .05;

^**p < .01.