Conclusion and Discussion

Figure 5.15 Graph representing the comparison of the results of the first and second steps of the test

related colour temperatures. At values of 2970 K and 2940 K, half of the subjects answered they perceived a little difference between colours. From 2910K to 2820K, most subjects identified a little difference between colours; increasing up to 2700K when all the subjects perceived the difference in colours as a big difference.

Comparing the two charts from Step 1 and Step 2, the most common answers differ slightly at each point on the correlated colour temperature graphs. At 2700K most subjects were able to see a big variation, while from 2820 K to 2910K, on both steps, the participants perceived a slight difference. In the second step, participants continued perceiving the small difference until 2970K. From 3000K to 3030K most subjects answered with values close to 1 (No variation), especially at 2970K for Step 2 and at 3030K to 3060K for Step 1.

The graph differs slightly after 3000K, with Step 2 registering higher values than Step 1 in all correlated colour temperature values until 3420K. Only at 3390K, there is a higher perception in the variation for the Step 1 process. In conclusion, considering the Step 2 part of the experiment, the subjects identified the changes in colours with a smaller change in correlated colour temperature compared with Step 1. Step 1 registered higher values than Step 2 for lower K, at 2790K and 2910K. Conclusion and Discussion

The data shows that to perceive the difference between two different correlated colour temperatures, the value of that difference needs to be

higher than 30 Kelvin degrees when colours are presented nonadjacent. Thus, the hypothesis “if there is a variation of more than 30K in the range of 3000K, then people will perceive the variation under mesopic vision conditions” was refuted. A difference of more than 90 Kelvin degrees was necessary, both for warmer and cooler correlated colour temperatures, starting from 3000K. In the case where the colours were presented adjacent, a difference of 30K for warmer correlated colour temperature and a variation of 60K was necessary for participants to perceive the variation. In this case, the hypothesis “if colour samples are presented adjacent, then a smaller colour variation will be noticeable compared when colours are presented nonadjacent” was partially corroborated.

The participant group for the test was homogeneous in age, including participants from 23 to 30 years of age. In addition, all participants but one was Lighting Design students, which according to Brown’s findings, people can experience a learning effect after being exposed to the same stimuli recurrently (Narendran et al., 2000). In consequence, the results could have to vary incorporating people with older age with different visual capabilities and with diverse backgrounds.

The effect produced by the colour interaction between the yellow wall where the TV screen was located was not considered. Due to the characteristics of a TV screen, absolute black was not possible for the surroundings of the colour samples, since a brightness of 0.036 cd/m2 was measured. In addition, the variation of the brightness during the transition of the slides produced a flash effect on the participants which could have altered their perception. Another effect mentioned by the participants was the presence of an afterimage on the slides for the second step, caused by the lines pre-