Novel forms of cross-modal perception might show up at any moment.
Several years ago, I read the research paper “One Shot Synesthesia” (Alexandra Kirschner and Danko Nikolić, Translational Neuroscience, 2017 Nov 25. doi: 10.1515/tnsci-2017-0023). The authors' theory that all of us “have the capability to creatively construct novel synesthetic experiences as events unfold in [our] lives” deeply resonated with me. I am a polysynesthete with multiple forms of cross-modal perception that are with me every day; however, I've only once had an occurrence of taste->color/pattern synesthesia. That experience was so robust, it has forever impacted the way I understand my neurocognitive differences.
I was standing in my kitchen eating a Thai curry straight out of the carton. When I took the first bite, fingers of cobalt blue light flashed across my visual field, projecting into my peripheral vision on the left side of my face. These blue forms were punctuated by chartreuse and yellow “floaters”; I don't know what else to call them. The experience was so intense and unfamiliar, I found it a little frightening. Then, I recognized the perception for what it was: one shot synesthesia. Perhaps it was launched by the fact that I was ravenously hungry, so ready to eat that I didn't bother to plate my food. Maybe my one shot synesthesia was fostered by the unusual flavors of the green curry. Whatever the reason, that gustatory synesthesia left its mark, not only in terms of my recollection of the visual phenomena but also in my understanding that my synesthesia isn't always neatly contained into reliable categories. Novel forms of cross-modal perception might show up at any moment. I look forward to another instance of one shot synesthesia.
One Shot Synesthesia (Click to enlarge)