The percentage of correctly identified letters was used as the short-term visual performance measure. The correctness was checked by the computer recorded file and the subjects’ writing sheet. The correctness was also determined by the position sequence of recall. For example, if the presented position sequence from a particular trial was BMSQ, then the response of MSQB would not be correct. In the present study, the mean percentage (mean of correct character identification percentage) for all of the 10 female and the 10 male subjects together were used instead of individual character identification performance to avoid the confounding of subjects’ difference. Analysis of variance (ANOVA) and calculation of effect size (2) [12, 13] were conducted using Statistical Products & Service Solutions (SPSS 13.0).