000K utf8 1100 $c2020 1500 eng 2050 urn:nbn:de:gbv:8-mods-2020-00456-4 2051 10.3389/fnins.2020.00298 3000 Keil, Julian 4000 Double Flash Illusions$dCurrent Findings and Future Directions [Keil, Julian] 4209 Twenty years ago, the first report on the sound-induced double flash illusion, a visual illusion induced by sound, was published. In this paradigm, participants are presented with different numbers of auditory and visual stimuli. In case of an incongruent number of auditory and visual stimuli, the influence of auditory information on visual perception can lead to the perception of the illusion. Thus, combining two auditory stimuli with one visual stimulus can induce the perception of two visual stimuli, the so-called fission illusion. Alternatively, combining one auditory stimulus with two visual stimuli can induce the perception of one visual stimulus, the so-called fusion illusion. Overall, current research shows that the illusion is a reliable indicator of multisensory integration. It has also been replicated using different stimulus combinations, such as visual and tactile stimuli. Importantly, the robustness of the illusion allows the widespread use for assessing multisensory integration across different groups of healthy participants and clinical populations and in various task setting. This review will give an overview of the experimental evidence supporting the illusion, the current state of research concerning the influence of cognitive processes on the illusion, the neural mechanisms underlying the illusion, and future research directions. Moreover, an exemplary experimental setup will be described with different options to examine perception, alongside code to test and replicate the illusion online or in the laboratory. 4950 https://doi.org/10.3389/fnins.2020.00298$xR$3Volltext$534 4950 https://nbn-resolving.org/urn:nbn:de:gbv:8-mods-2020-00456-4$xR$3Volltext$534 4961 https://macau.uni-kiel.de/receive/macau_mods_00000859 5051 150 5550 Congruence 5550 Crossmodal Influence 5550 Double Flash Illusion 5550 Multisensory Integration 5550 perception 5550 Sound-induced Flash Illusion