Our 10-year-old Chattering son appears to be a synesthete, which in his case means that he “sees” letters in color and perceives the taste of foods on a “mental” grid or graph.

A fair share of famous artists and composers have had synesthesia, a involuntary sensory irregularity in which some of the five senses cross into each other. Musical notes may be “seen” in color, or smells might be grouped visually as circles, squares, or triangles. I first learned of synesthesia when I read Vladimir Nabokov’s autobiography “Speak Memory,” and found this sort of sensory profile so wonderful to contemplate that I never forgot about it. Once considered extremely rare, sensory overlaps may actually occur in as many as three percent of all people.

Young Chat has always been able to hear more than most people in one ear (our pediatrician insisted we see an audiologist to have the irregularity tested when he was very young). He’s also been hugely appreciative of the complex flavorings of many ethnic cuisines in restaurants. And lately, his remarks when cooking with me in the kitchen have seemed so odd. “Oh Mom,” he declared while making his usual Asian dumpling dipping sauce for our carryout: “The taste of this sauce goes way up, then goes flat for awhile, and then comes up, and goes down again.” Could he one day be a skilled wine taster or “nose” for a perfume company?

“He seems to chart the tastes of foods like he’s drawing them on graph paper,” I told my sister on the phone last week.

“Well, he might have synesthesia!” she said, always the one to point stuff out to me.

“Hey honey, do you see letters in color?” I called out to him, phone still in hand (admittedly, not the best way to tease scientific information out of somebody).

My son said “yes” very emphatically.

So Mr. Chattering cheerfully sat him down and went through the alphabet several times, reviewing letters in random order, and discovered that yes, our son has involuntary color associations for letters that are fixed in his mind as realities. A and R are red in nature. B, G, H, and O are blue. Lots of letters seem green: E, I, V, T, J, S. The letter Y is white. D and C are inexplicably silver. Apparently, not all synesthetes assign the same colors in the same way, so there’s no making sense of it. Young Chat can read books without being distracted; it’s just when he thinks about the letters individually, and savors their character, that the colors come up loud and clear.

For me, certain acupunture points on my body, when needled, have colors to them. But I don’t know what they are until I feel them. That’s the only way I can relate. So we’ve just joined the American Synesthesia Association, which has annual conventions and is fueling a revival of deeper inquiry.

Do your senses ever lapse into each other? Do you know any synesthetes? Why do you think someone would be born with these kinds of sensory crossovers? Fun to think about, isn’t it?