Did someone with spatial-sequence synaesthesia design the calendar app on mobile phones? Because that’s how time and dates look in my brain. If you say a date to me, that day appears in a grid diagram in my head, and it shows if that box is already imprinted with a holiday, event or someone’s birthday. Public holidays and special events like Christmas and Easter are already imprinted for the year, and the diagram goes backwards to about 100,000BC and then forwards all the way to about the year 2500 before tapering off.

It was only in my 60s that I discovered there was a name for this phenomenon – not just the way time appears in this 3D sort of calendar pattern, but the colours seen when I think of certain words. Two decades previously, I’d mentioned to a friend that Tuesdays were yellow and she’d looked at me in the same strange, befuddled way that family members always had when told about the calendar in my head. Out of embarrassment, it was never discussed further. I was clearly very odd.

The funny thing is I’d been working as a GP for more than 30 years before discovering there was a word for the way my brain worked. One day, while doing some research into managing anxiety for my paediatric patients, I stumbled across some research from Macquarie University in Sydney about grapheme-colour synaesthesia. Other people were similarly affected, apparently. Then I learned about another common form of the phenomenon, called spatial-sequence synaesthesia, which fitted with my experiences of not only seeing time in a 3D pattern but numbers and letters too. Perhaps I was not so odd after all.

I joined both research projects and learned so much about my own form of synaesthesia and other people’s. It is estimated that 10% to 20% per cent of the population have some form of spatial-sequence synaesthesia but we don’t all see time in the same way. Some people see minutes, hours, days and weeks going around in a circle or square pattern, whereas for me they go from left to right and veer up and down.

While thinking about the moment in time I’m at now, I see the day of the week and the hours of that day drawn up in a grid pattern. I am physically in that diagram in my head – and there’s a photographic element to it. If there’s a concert coming up in the calendar, in my mind, a picture of the concert venue is superimposed on to the 7pm to 10pm time slot on that particular day.

The alphabet and numbers also follow particular patterns in my mind’s eye.

The main benefit day-to-day is memory. The patterns have helped with maths and handling money: I don’t need a calculator for basic arithmetic and, if I’m comparing prices, the amounts sit relative to other prices on a number map in my head. It’s helpful for remembering dates, too. I remember the birthdays of friends I haven’t seen for 65 years and I can picture my kindergarten classroom in vivid detail: its location in the building, the mats we sat on and the plastic templates of the Australian states that we drew around.

When it comes to planning, synaesthesia is no longer as useful an asset as it once was, given that most of us have diaries and reminders on our phones. But it can be handy for history or geography rounds on trivia nights when phones aren’t allowed.

Sometimes I’d like to be more laissez-faire and less structured in my head but I do find it fascinating. Neural patterns will become better understood as science becomes more sophisticated but, in the meantime, the wonder of it all is quite appealing. Neuro-researchers can have my brain one day, and I would love to get into someone else’s head and see what they see.

We are all alike and yet our brains are surprisingly different. Long may that continue.

• Anina Rich, a cognitive neuroscientist and chair of the synaesthesia research group at Macquarie University, assisted in reporting this series