# Koffka Ring Perception in Digital Environments with Brightness Modulation
## 4 Discussion  
The results of the statistical analysis--including descriptive statistics, [PERSON]'s ANOVA for dependent samples with repeated measurements, and post hoc Wilcox tests--demonstrate that the visual effect induced by the Koffka ring varies significantly depending on the brightness of the stimuli, the design variant of the Koffka ring, and the color of the background. The strongest effect was observed for dark stimuli, particularly on blue/green and red/green backgrounds in variant b of the Koffka ring design. For middle stimuli, the effect was also pronounced in variant b, while for light stimuli, the effect was generally weak or absent, except for specific combinations where it was noticeable. [PERSON] and [PERSON] demonstrated that perceptual organization can override local surrounding effects in determining simultaneous lightness contrast, emphasizing the importance of spatial arrangement in visual perception [14]. Our results are consistent with this principle, as variant b of the Koffka ring--where the ring is split between two different backgrounds--showed the strongest effect, suggesting that spatial organization and background color are critical factors in the perception of brightness differences. [PERSON] was the first to define simultaneous contrast as a shift in a color's tone and darkness toward the complementary color adjacent to it [15]. Our results confirm that this effect is most pronounced for dark stimuli, which is in line with [PERSON]'s observations. Furthermore, the findings are supported by theories of lateral inhibition in the retina, as discussed by \begin{table}
\begin{tabular}{l c c c c c c c c} \hline \hline
**Samples** & **Sample 1** & **Sample 2** & **Sample 3** & **Sample 10** & **Sample 11** & **Sample 12** & **Sample 19** & **Sample 20** \\ \hline Sample 2 & 0.807 & - & & & & & & \\ Sample 3 & 0.007 & 0.002 & - & - & & & & \\ Sample 10 & 0.947 & 0.798 & 0.006 & - & & & & \\ Sample 11 & 0.693 & 0.639 & 0.008 & 0.806 & - & & & \\ Sample 12 & 0.028 & 0.009 & 0.353 & 0.055 & 0.030 & - & & \\ Sample 19 & 0.004 & 0.003 & 0.757 & 0.000 & 0.001 & 0.538 & - & \\ Sample 20 & 0.007 & 0.005 & 0.850 & 0.000 & 0.010 & 0.294 & 0.745 & - \\ Sample 21 & 0.001 & 0.000 & 0.805 & 0.001 & 0.002 & 0.107 & 0.527 & 0.661 \\ \hline \hline \end{tabular} Legend: This table contains Wilcox tests’ \(p\)-values.  
\end{table} 
Table 11: Results of Wilcox dark primary stimuli tests. [PERSON], [PERSON], and [PERSON], which explains how adjacent visual stimuli can inhibit each other, leading to perceived differences in brightness. [PERSON] et al. investigated the simultaneous contrast effect in both analog and digital media, and our study extends these findings by demonstrating that, even on digital displays, the effect is robust and depends on the combination of background color and the spatial organization of stimuli [17; 18; 19; 20; 21]. The effect was particularly strong for blue/green and red/green backgrounds, while it was weak for red/blue backgrounds across all brightness levels. [PERSON] et al. showed that the Koffka ring effect depends on the thickness of the ring rather than its continuity [27]. Our results indicate that, in addition to thickness, the spatial arrangement and background color play crucial roles. Variant b, with its split design, produced the strongest effect, highlighting the importance of perceptual organization in determining the strength of the simultaneous contrast effect. In this research, a computer screen was used as a digital medium with the goal of determining the strength of the perceived Koffka effect when using a certain color combination of primary and secondary stimuli in the design of a conceptual graphic solution in real graphic production. The experiment was conducted on a single type of digital display, potentially limiting the applicability of the findings to other devices or display technologies.