No statistical methods were used to pre-determine sample sizes but our sample sizes are similar to those reported in previous publications 22, 23, 46. 154 subjects gave written consent to procedures approved by the Boston University Institutional Review Board and were paid. Of the 91 subjects in Experiment 1, five were excluded due to excessive eye movements and two voluntarily withdrew before completing the study. Data on the remaining 84 subjects were analyzed. 42 subjects were younger adults aged 20 to 29 years old (mean age 24.4 ± 2.8 SD, 20 female, all right-handed, mean years of education 15.7 ± 1.3 SD), and 42 were older adults aged 60 to 76 years old (mean age 68.8 ± 4.4 SD, 22 female, all right-handed, mean years of education 17.0 ± 2.3 SD). Of the 31 subjects in Experiment 2, three voluntarily withdrew before completing the study. Data on the remaining 28 subjects (aged 62–75 years, mean age 69.6 ± 3.7 SD, 14 female, all right-handed, mean years of education 16.4 ± 1.4 SD) were analyzed. Of the 18 subjects in Experiment
