## 2 Method
### Experimental Procedure  
The procedure for Exp.1 and Exp.2 is shown in Figure 1 above. Before the formal experiments, all the luminaires were switched on for at least 30 min to ensure they had stabilized. Upon arrival, the subjects randomly chose a seat and signed an informed consent form. A general information questionnaire was issued to collect demographic and lighting knowledge information. During that time, the experimenter read the instructions and answered any questions raised by the subjects. The subjects then consecutively performed the six tasks in Session 1. The first task was to observe a plate of multicoloured fruit and vegetables (including an apple, an orange, a lemon, an onion, a green date, a cucumber, and some cherry tomatoes; Figure 5), and make a subjective preference rating. Note that the fruit and vegetables adopted in Exp.1 and Exp.2 were not the same due to the timescale of the experiments affecting the long-term preservation of the items. In Exp.2, therefore, the fruit and vegetables were selected to be as similar to those use in Exp.1 as possible. A 7-point categorical judgement method was employed to quantify the subjective preference of the illuminated objects. Specifically, the seven scores (\(-3\), \(-2\), \(-1\), \(0\), \(1\), \(2\), \(3\)) corresponded to _strongly dislike_, _moderately dislike_, _slightly dislike_, _neutral_, _slightly like_, _moderately like_, and _strongly like_, respectively. This method was also adopted for the preference evaluation of the skin tone of the back of the hand of each subject, as shown in Figure 5.  
In the third task, subjects were asked to assess the atmosphere of the lighting environment according to four perceptual attributes: _Uncomfortable/Comfortable_, _Cool/Warm_, _Negative/Active_, and _Tense/Relaxed_. Figure 6 shows the questionnaire used to record these measurements, in which a score of \(+3\) corresponded to the highest degree of comfort, warmth, activeness, and relaxation, respectively. Figure 5: Colour preference judgements of fruit and vegetables (**left**) and skin tone (**right**). Figure 6: Questionnaire used for recording the subjective rating of the atmosphere of the lighting environment. The subjective evaluation of the lighting was followed by the Anfimov test, which was designed to measure attention and mental workability [49; 50; 51; 52]. As can be seen in Figure 7, the test comprises 1200 uppercase letters printed as a justified paragraph (without hyphenation) on a 210 \(\times\) 297 mm (A4) sheet of paper. The paragraph consists of 8 letters (A, B, C, E, H, K, N, X) such that each letter randomly appears 150 times (organized into 30 lines with 40 letters in each line). The text was presented in 14 pt Times New Roman font and contained 20 pairs of the two given letters \(EK\) (in sequence) whose positions were randomized and counterbalanced. Note that all the Anfimov tests conducted in this study had different text paragraphs with different arrangements of letters. During the test, the subjects were instructed to read the letters one by one (beginning at the upper left) and to underline the letter \(K\) in the preset pair \(EK\), all within 2 min. In addition, they needed to mark the last letter they read when the time was up. Each subject had to complete three Anfimov tests in Session 1, each using a different coloured piece of paper--white, yellowish-white, and green, respectively. The order of the three Anfimov tests was randomized and a break of 1 min was allowed between each test. After the Anfimov test, the reading comfort assessment was performed, during which the subjects had to read the questionnaires used in the Anfimov test (Figure 7) and conduct the assessment of reading comfort. These questionnaires contained sentences in Chinese and English (including the uppercases letters in the Anfimov test), as well as Arabic numerals. The 7-point judgement method was again adopted with a score of +3 relating to the most comfortable reading experience.