. 2018 Sep 5;13(9):e0201976. doi: 10.1371/journal.pone.0201976

Table 2. Overview of effects of surface luminance on the perceived layout of interior space, as a function of the room surface that was varied in luminance, and the room dimension that was judged by the observers.

$\bar{S}$ indicates the mean simulated size of the judged spatial dimension. Y_b and Y_d indicate the luminance of the brightest and the darkest presented surface color, respectively. The difference in perceived brightness (ΔB), the mean difference in perceived spatial extent ( ${\bar{Δ}}_{b - d}$ ), and Cohen's [37] d_z are reported for the comparison of the brightest and darkest presented surface color. We calculated the difference in perceived brightness between the dark and the bright stimulus by ΔB = Y_b^0.33−Y_d^0.33, where the power function links the perceived brightness B to the physical luminance Y (e.g., [39], see also [40,41]). Bold d_z-values indicate significant effects (p < .05). Effects of bounding-surface luminance are highlighted by a gray background.

Surface with luminance variation	Judged dimension	Study	Experiment	$\bar{S}$ (cm)	Y_b (cd m^-2)	Y_d (cd m^-2)	ΔB	${\bar{Δ}}_{b - d}$ (cm)	d_z
Ceiling	Height	Oberfeld et al. (2010) [21]	1	300	^a	^a		8.56	0.66
		Oberfeld et al. (2010) [21]	2	300	^a	^a		3.64	0.50
		Oberfeld & Hecht (2011) [22]	2	300	^a	^a		3.76	0.63
		Oberfeld & Hecht (2011) [22]	3	300	^a	^a		7.63	0.46
		von Castell et al. (2017) [23]	3 (matching task ^b)	300	17.51	1.05	1.56	1.93	0.79
		von Castell et al. (2017) [23]	3 (verbal estimates)	300	17.51	1.05	1.56	3.38	0.51
		von Castell et al. (in press) [24]	Chromatic colors	300	13.74	4.76	0.70	1.40	0.47
		von Castell et al. (in press) [24]	Achromatic colors	300	13.78	4.70	0.70	1.17	0.28
	Width	Oberfeld & Hecht (2011) [22]	3	450	^a	^a		−6.07	0.38
	Width	Present study		450			1.06	2.14	0.25
	Depth	Present study		600	82.64	34.87	1.06	0.14	0.02
Side walls	Height	Oberfeld et al. (2010) [21] ^c		300	^a	^a		9.45	0.62
	Height	Oberfeld & Hecht (2011) [22] ^c	2	300	^a	^a		8.69	0.77
	Width	Present study		450	82.11	25.45	1.37	7.88	0.98
	Depth	Present study		600	82.11	25.45	1.37	4.09	0.32
Rear wall	Height	Oberfeld et al. (2010) [21] ^c		300	^a	^a		9.45	0.62
	Height	Oberfeld & Hecht (2011) [22] ^c	2	300	^a	^a		8.69	0.77
	Width	Present study		450	82.08	25.46	1.37	3.97	0.38
	Depth	Present study		600	82.08	25.46	1.37	6.84	0.62

Note:

^a No luminance measurement available.

^b Results for the comparison stimulus (pillar) presented at a distance of 4.50 m from the observer (for a discussion see [23]).

^c No independent variation of side-wall and rear-wall luminance.