[rebuilder]

My wife has fairly classic synesthesia, with letters and numbers having colours and "character" etc. I don't have that, but I do have exactly what you described with numbers, months of the year, and years having an unchanging position in a mental 3-d model. The model for each of these is a bit different, but each could be described as a kind of winding road.

So I wouldn't say I'm synesthetic, but at the same time I can't really point to a clear difference between how my mind associates numbers with locations in a spatial structure, and how my wife's mind associates them with colours.

I also can't really say how those associations are different from the kinds of associations that the mind seems to make to anchor new experiences and information into memory. I'm not explaining that very well, but overall I half think synesthesia seems more like just an atypical manifestation of a probably universal human trait, and less like a rare oddity.

[jraph]

I also have some representation for numbers and for the days of the week, but it would not be 3D, more like 2D, and kind of dynamic, too: the view is relative to the “focused” number / day. Same thing as you, the representations are different for numbers, days of the week and months. The days are horizontal, and months too. Numbers, not so much. Kind of horizontal up to ten, and then vertical up to twenty, and then I would not know how to describe it. There is a kind of break for each tens up to one hundred, with numbers being mostly horizontal but not quiet, and each teen somewhat higher than the previous one. Negatives have the exact same place as there opposite. Days of the months are the same as numbers. Anyway, describing this is kind of pointless. This representation does not feel very precise.

These representations are the same since as far as I can remember. I know that some people I discussed with don't think they have such a representation for numbers or dates. It seems to correspond to the description given in [1].

I think it may have an impact on my memory, at least for dates (but nothing extraordinary). It's usually easy to remember meetings and events in the year, because they somewhat appear in the representation, I don't really need a calendar if there are not too much things scheduled (but I note in a log, just in case, and it's not completely reliable too).

You might have calendar synesthesia [2,3], and maybe me too, but maybe weaker than yours or my father's.

And yeah, it's not something we really see, its a representation that automatically comes into the mind without us trying to at all. Right?

Maybe many people actually have some form of synesthesia.

[1] https://en.wikipedia.org/wiki/Synesthesia#Number_form

[2] https://www.thecut.com/2016/11/the-form-of-synesthesia-where...

[3] https://fr.wikipedia.org/wiki/Synesth%C3%A9sie#Synesth%C3%A9...

Translation of [3]:

> Like “numerical synesthesia”, spatio-temporal synesthesia is a mental map of the days of the week and/or months of the year. People having this kind of synesthesia state that they can “see the time” as a ribbon, a ring or a circle for instance. According to some studies, these people would have particular synaptic connections in their brain, allowing them to live time like a spatial construction.

> Like all the forms of synesthesia, “spatio-temporal” also shows a permanent feature: tested months later, someone having synesthesia will report the same experiences they had previously reported.

[rebuilder]

Calendar synesthesia sounds like a good match with mine, although for me it's very much a "mind's eye" thing, not like an image projected into my visual field. In article 2, the researchers are said to have asked their subject to recite every third month going backwards, apparently to test that it's not just a mind's eye visualization. I get similar speeds as their test subject, and do go through the months in my mental image to help with the task. However, since for me it is a mind's eye visualization, I'm not sure the test as described is very useful.

The Wikipedia article points out that in theory, all logical synesthetic combinations are possible. I suspect that if you tested broadly for any kind of synesthetic experiences, you'd find a significant portion of the population had them, maybe even the majority.

[jraph]

> for me it's very much a "mind's eye" thing, not like an image projected into my visual field

Same for me.

> In article 2, the researchers are said to have asked their subject to recite every third month going backwards, apparently to test that it's not just a mind's eye visualization

I would be terrible at this task. I don't see the whole year (week) at once. This representation would not be of any help for that. It's here when I am scheduling / planning, or when someone is saying / I'm reading a date.