The Influence of Speed and Amplitude on Visibility and Perceived Subtlety of Dynamic Light

摘要

LED lighting can provide pleasant temporal dynamics,rnthough the understanding of what constitutes pleasant has so farrnremained largely in the experiential domain of lighting designers.rnOnly recently has research begun to uncover what affectsrnpreferences for dynamic lighting. Based on the insight that visible,rnyet subtle, dynamic lighting is desirable, an experiment wasrnconducted which studied the influence of the speed and amplitudernof periodic temporal color transitions on the thresholds forrnvisibility and perceived subtlety. Using RGB LED lights tornilluminate a wall in a living room setting, stimuli with periodicrncolor transitions were presented to 40 observers, half of whomrnevaluated whether the dynamic transitions were visible, and half ofrnwhom evaluated whether the dynamics were subtle. Thernobservers’ data were fit using psychometric surfaces over thernindependent variables speed and amplitude of transitions. The 2Drncontours at the middle of the height of these surfaces were taken asrnthresholds. Experimental confidence was estimated viarnparametric bootstrapping, showing significant effects of thernlocation and direction in color space in which the transitions werernmade, further strengthening the need for a temporal differencernbased color space. Interestingly, a distinct difference between thernthreshold for visibility and the threshold for subtlety can be seen,rnallowing for the creation of transitions that are both visibly andrnyet subtly dynamic. The results indicated that observers are morernsensitive to hue changes than to chroma changes, and observersrnare more sensitive to hue changes in the orange region than tornthose in the blue region. Additionally, questionnaire responsesrnprovided insight into interpretations of the word subtle,rnunderstood to be pleasant, gentle, and smooth, which are alsornterms used to describe desired characteristics of dynamic lighting.