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Number-form synesthesia

Also occasionally called number-space synesthesia

A type of spatial sequence synesthesia

(Image: Ailsa in Ailsa Brims Fine Art)

People with this type of synesthesia perceive numbers as a sequence visualised spatially, around them or in front of them. The spatial positioning is highly consistent and tends not to vary throughout the synesthete’s lifetime. For many of these people, each number also has its own colour (so number-form coexists with grapheme-colour synesthesia in this case), or their number maps have shading effects. These synesthetes frequently visualise the numbers spatially in relation to themselves, with a perspective that varies according to the number they have in mind at any given time. The maps are three-dimensional and assume many different forms: they can be straight or curving, with one or more changes of direction, with right angles, peaks and dips, spirals, zigzags, steps or ladder-like structures, going from right to left or vice versa, climbing up or disappearing on the horizon as the numbers get larger, and they may look tidy and well-organised or appear chaotic, only making sense to their “owner”. In any case, it can safely be said that there are as many spatial numerical maps as there are number-form synesthetes, as this type of synesthesia is just as idiosyncratic as any other.

(Image: Sarah, in the blog Terra Nomad.)

What percentage of synesthetes have this specific subtype? There do not appear to be any studies giving a conclusive number, but it probably occurs in the majority of people who have calendar synesthesia (estimated at 20%, N. Sagiv et al, 2005) and also in some others who do not have the calendar type, so it is likely to be relatively common.  

Projector synesthetes, who are a minority, see their sequences physically in the space around them, while associators perceive a well-defined and consistent map in their mind’s eye, always present in their lives.

(Image: from the book Des Phénomènes de Synopsie by Théodore Flournoy, 1893, p163.)


Having this type of synesthesia often helps the synesthete to perform mental calculations and these people sometimes excel at mathematics, as they can easily navigate through their visual numbers, handling and remembering them at will.

(Image: Francis Galton, 1881)


All the above examples are for natural numbers, but there are also synesthetes with mental maps for other numerical sequences: age, height and/or weight measurements, temperatures (meteorological or body temperature), clothes sizes, shoe sizes, salaries and so on.

(Images: Weight in lbs and people’s ages, by Rebecca Schulz Kluchnyk, posted to the Facebook group Synesthesia. 2020.)


Go to the page on spatial sequence synesthesia in general

Go to the page on alphabet-form synesthesia


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