Carsten Höller’s Light Wall (2021) consists of a metal structure holding 1,100 lightbulbs which are simultaneously blinking at a frequency of 7,8 Hz. This rhythm has a visual (and auditory) hallucinatory effect on the viewer, as it presumably influences brainwave frequencies in the visitors exposed to the powerful on and off of the lights (there is a sound element too: a stereo click at the same frequency). Created as an original outdoor piece for Noor Riyadh 2021, the work sends its light pulses towards the audience and surrounding buildings in Riyadh. It calls into question the reliability of what is perceived as given, which is foremost the constancy of both natural and artificial light. At the same time, it produces beautiful, dreamlike “color field” hallucinations, especially with closed eyes. One’s own thoughts, spoken words, and behavior in general are influenced by the flickering lights and clicking sounds, with the result that not only the perceived but also its interpretation is different.