Table 5.
Global and local switch costs in terms of nondecision time component 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 | 0.04 | 0.01 | [0.03,0.06] | 0.06 | 0.01 | [0.03,0.08] | G | 41.70** | 2 | 0.43 | 1 | t(52.9) = 5.0** | t(46.1) = 6.3** |
| 61–74 year olds | 0.09 | 0.01 | [0.07,0.10] | 0.14 | 0.01 | [0.11,0.17] | T | 37.23** | 1 | 0.26 | 2 | t(25.6) = 5.7** | t(22.1) = 5.2** |
| 75–89 year olds | 0.11 | 0.01 | [0.09,0.13] | 0.19 | 0.02 | [0.15,0.23] | C | 128.15** | 1 | 0.54 | 3 | t(41.3) = 1.7 | t(30.5) = 1.8 |
| Brightness Discrimination Task | |||||||||||||
| College Students | 0.02 | 0.01 | [0.0,0.06] | 0.13 | 0.02 | [0.09,0.18] | G × T | 9.90** | 2 | 0.15 | 1 | t(47.1) = 4.7** | t(48.8) = 5.7** |
| 61–74 year olds | 0.10 | 0.02 | [0.06,0.14] | 0.30 | 0.02 | [0.25,0.36] | G × C | 6.54** | 2 | 0.11 | 2 | t(22.0) = 1.5 | t(25.2) = 3.2** |
| 75–89 year olds | 0.08 | 0.02 | [0.02,0.13] | 0.25 | 0.03 | [0.18,0.33] | C × T | 44.26** | 1 | 0.29 | 3 | t(28.9) = −0.6 | t(45.0) = −1.1 |
| G × C × T | 1.53 | 2 | 0.03 | ||||||||||
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.