I'll never forget, I was like 7 years old. I closed my eyes, and that's when it started. I started seeing sounds Joe sat across the crackling campfire from me that evening, his dirty flannel shirt bearing the markings of our hard day of fieldwork. His wrinkled brow was dusty and slightly sunburnt, gray hair tousled under his worn cap. We'd found some amazing fossils, but it was a brutal day of digging and hard labor under the unrelenting sun of the New Mexico badlands, and Joe was no spring chicken. For a rare moment, the perpetually sunny smile left his face. As I watched, he leaned over, sighed, and rubbed his arthritic right knee, wincing at the residual pain from the day's toils. Suddenly, an almost-overwhelming lightning bolt of pain shot through my knee and up into my thigh. But I didn't have arthritis and I wasn't injured. Rather, I have synesthesia, a neurological condition that causes sensory experiences to get … mixed up. My synesthetic brain had seen Joe's knee pain and mistakenly interpreted it as my own, radiating acute pain sensations down my leg. Synesthesia is a type of sensory perception in which stimulation of one sense triggers an automatic response in another sense or cognitive pathway. The term comes from the Greek words for together (syn) and sensations (esthesia); as in, multiple sensations are experienced concurrently. Synesthetes process information simultaneously across multiple regions of the brain, creating a secondary sensory experience. For example, tastes may trigger sounds or smells in the perceiver's brain (lexical-gustatory synesthesia). Or, as in the case of musician Pharell Williams and other chromesthesia-type synesthetes, sounds may have visual qualities or colors. French composer Gautier Serra (stage name Igorrr) perceives music as colors, which influence the eccentrically remarkable stylings of his musical cooperative. “As I got synesthesia, I see the tracks as paintings. In order to create the painting, I need different colors, which means for me different instruments. Since I know what to record and where to place it, I can start the recordings” (Martin, 2017). I recently saw Igorrr perform an amazing live show in a tiny, dingy, sweltering, underground basement club, Nile Theater in Mesa, AZ. As the musically induced colors swirled around me and my brain buzzed with vibrations, I wondered how my synesthetic visions compared to Serra's mental paintings. The closest analogy I can conjure is that it was like watching a heavy metal version of the trippy Disney movie Fantasia in my head. As I slept one night, a light flicked on in the kitchen. In my half-conscious state, I heard it first, a deep rumble swelling towards me as if the air were vibrating, booming louder as it got closer. Then the color came: vivid, aquamarine waves rolling in layered sheets towards me. When the waves reached my face, I felt them gently break against the bridge of my nose before rolling upwards across my forehead. In reality, it was only a light turning on, but to me it arrived as a multi-sensory tide: sound, sight, and touch layered into one experience. Many “flavors” (pun intended) of synesthesia involve numbers. In grapheme–color synesthesia (my primary type), certain numbers have colors or other inherent characteristics. For example, in my brain, 12 is round and a rich royal blue, while 6 is decidedly orange. Four is yellow and bitter, slightly sharp. Seventeen is completely untrustworthy. In spatial-sequence synesthesia, dates such as months, days, or years appear visually in a sequence. For example, my mental calendar is arranged like a square with the seasons arranged clockwise chronically along each edge (spring months along the bottom, summer months along the left side, autumn across the top, and winter down the right side). Years are arranged in rows by decade and century. Upon hearing or reading a particular year, my mental calendar visually zips along the row to that decade and then focuses in on the year. These visualizations occur instantaneously and involuntarily whenever I encounter any date. Synesthetic experiences exist along a continuum from strong, consistent sensations (mine are often so visually stunning and all-consuming that it's like watching a movie that outshines the world around me) to milder, hazier effects. Animal science researcher and autism advocate Temple Grandin once said, “I'm a visual thinker not a language-based thinker. My mind is like Google Images.” The same is true of many synesthetes: Sounds, smells, tastes, and even numbers may conjure up such striking visual images that we are often “thinking in pictures” (the title of Grandin's autobiography) or “seeing sounds” (like Pharell). As many as 4%–7% of the population may experience some degree of synesthesia, although the rates are 3 times higher in people on the autism spectrum (Baron-Cohen et al., 2013). While the precise mechanisms are not well understood, both conditions appear to involve reduced synaptic pruning during development leaving more interconnections among cortical pathways (Matuskey et al., 2025). While it may be tempting to look at these conditions as disorders, they can genuinely be a strength. I lean into my neurodivergence and try to capitalize on the unique interconnections that allow me to see the world differently. I enjoy being able to visualize data in novel ways, approach problems from a unique angle, and see unusual connections that ultimately spur innovation. Again, to quote Temple Grandin, we are “Different, not less.” As I was recently reminded by a fellow neurodivergent: We all contain multitudes. In this Special Issue of The Anatomical Record, we celebrate the fascinating world of sensory perceptions across vertebrates. The volume brings together a collection of papers on special senses ranging from neurosensory diversity in synapsids (Benoit et al., 2026, this issue) to cochlear echolocation in bats (Anthwal et al., 2026, this issue) to visual acuity in flounders (Moreno Smith, 2023; Smith et al., 2023). Tim is also a talented artist and has generated many lovely cover images for AR Special Issues. In all, special senses are a crucial and fascinating mechanism by which animals experience the world. Whether your senses act individually or are synesthetically intertwined, we hope you enjoy the collection of papers on the sensory world of vertebrates in this novel Special Issue. Thank you for reading. Heather F. Smith: Writing – original draft; conceptualization; visualization; investigation. Jeffrey T. Laitman: Writing – review and editing; validation. On behalf of The Anatomical Record, the authors would like to express our sincere thanks to the energetic guest editors, talented authors, and dedicated reviewers who made this excellent volume possible. HFS would also like to thank JDC for insightful discussions on neurodivergence that helped shape this piece, and for the important reminder that neurodivergent minds are not contradictions, but resonating chords.
Smith et al. (Thu,) studied this question.