## 3 Results and Discussion
### Results of Anfimov Test  
In earlier studies, the Anfimov test has been commonly used to measure cognitive performance under different classroom lighting conditions [57; 58; 59]. To our knowledge, however, the impact of a practice effect or the degree of proficiency on the test results has not been investigated. Therefore, to investigate this issue, different groups of subjects with and without test experience in Exp.1 were invited to participate in Exp.2 (i.e., Group A and Group B). Note that results of the repeated tests within a defined experiment (i.e., data from Session 1 and Session 3) could not be used to validate the practice effect, since such repetition was confounded by visual fatigue caused by the two-hour self-study period in Session 2.  
The number of letters read per minute was used as a measure of proofreading speed and the proofreading accuracy (PA) was calculated as follows [52]:  
\[\text{PA}=(\gamma\div\sigma)\times 100\%, \tag{1}\]  
where \(\gamma\) and \(\sigma\) represent the number of times the letter K was correctly underlined by the subjects in the given pair of letters, \(EK\), and the total number of times the letter K should have been underlined in the assessed text (i.e., the text that had been read by the subject), respectively.  
Figure 9 illustrates the comparison of the Anfimov test results derived from experienced subjects (Group A) and inexperienced subjects (Group B) in Exp.2. In each experiment, two trials (i.e., tests in Session 1 and Session 3) were conducted. As can be seen, the subjects in Group A, with higher proficiency in the Anfimov test, always performed better in proofreading speed and accuracy than the subjects of Group B. This indicates that the Anfimov test is heavily influenced by the practice effect and this must be taken into consideration when implementing the test in further studies. In addition, the difference between test results of Session 1 and Session 3 for the two experiments was not so clear. A possible explanation is that although subjects might perform better in the second round of tests (i.e., Session 3), the visual fatigue caused by the two-hour study in Session 2 offset that improvement.  
The mean values of the subjects' proofreading speed and accuracy from Exp.1 and Exp.2 are shown in Figure 10. To remove the influence of the practice effect (proficiency), only the results of Group B in Exp.2 and the data of Exp.1 are shown. There is little difference between the results of Exp.1 and Exp.2 in most of the six comparisons (3 paper colours \(\times\) 2 sessions). The difference between Exp.1 and Exp.2 in terms of the proofreading accuracy using black text on yellowish-white paper (Figure 10, right) is relatively larger. However, as verified by the Mann-Whitney U test, there is actually no significant difference between Exp.1 (\(\sim\)6600 K-150 lux) and Exp.2 (\(\sim\)5100 K-300 lux) for all the six comparisons (\(p\) values \(>\) 0.05). That is, there is no significant effect of lighting environment on the Anfimov test results. [PERSON] et al. [57] found similar results, i.e., there was no significant difference between the results derived from the lighting conditions defined by 5000 K-300 lux and 6500 K-150  
Figure 9: The means of proofreading speed and accuracy of experienced (Group A) and inexperienced subjects (Group B) in Exp.2. The error bars depict the 95% confidence intervals.  
lux. In addition, the Mann-Whitney U test indicates that the test trial, paper colour, and gender have no statistically significant influence on the results of the Anfimov test (\(p\) values \(>\) 0.05).