The second most common type of synesthesia is ‘Space Sequence Synesthesia.’
Space Sequence synesthetes perceive dates and/or numbers in a spatial layout inside or outside their minds, and in a 2D or 3D arrangement. Like in “Grapheme-Color Synesthesia,” the ability to create vivid mental pictures correlates with external, 3D images. The opposite is true for vague, 2D images.
Space-sequence synesthetes claim to zoom in on events and recall them with better precision than average. This might be because synesthesia possesses characteristics of object (internal and detailed) and spatial (external and vague) visualizers. Paradoxically, SS synesthetes visualize specific areas with outstanding detail, but can also morph and rotate their spatial map.
The rotational model and navigational model are two different types of SSS. The rotational model comprises numbers or months moving toward the user, and the navigational model comprises numbers or months of moving away from the user.
About 2-20% of people have this kind of synesthesia. Estimates vary because there is not a scientific study to determine “SSS” occurrences in the general population. Stroop-like tests showed SSS and non-SSS react differently to stimuli. As an example, if the synesthete in the diagram above pointed to the front saying the word “January,” his response would be fast and concordant. But if the individual pointed to the back saying “January,” his response would be slow and incongruent. This does not occur with non-synesthetes.
Although this proves SSS is a legitimate phenomenon, SSS is often confused with the SNARC effect, an unconscious association of magnitude and positions. While both share similarities, a mix of environmental and developmental factors produce better average shape and color recognition results for SS synesthetes than non-synesthetes.
Environmental factors are heavily considered in synesthesia studies. For instance, scientists tested if colored magnets created associations in children that later developed into grapheme-color synesthesia. This theory was discarded. However, environmental factors have effects on SSS.
One environmental factor of SSS are time diagrams: It is an instinct to visualize numbers in a number line, like this:
People learn to think this way since childhood. Adult memory activates areas of the brain similar to children comparing numbers because people visualize years and numbers in a line. Teachers and parents reinforce this teaching the linear number system.
Numbers are represented like this because of one developmental factor: the phonological loop. The phonological loop is a conscious memory mechanism that develops around age six or seven. It allows people to retain information for one to two seconds before “rehearsing it.” When rehearsing, our mind maps out our mental math, memories, among other things.
In many cases, preference between spatial and non-spatial learning influences number rehearsal in children under six. Children who present difficulty in non-spatial learning visualize numbers in a 2D or 3D diagram or shape. And major events and decade changes can forge the visualization throughout life.
Synesthesia shapes are not constrained by social conventions, like left representing negative numbers or a circle representing a cycle. This leads to scattered patterns that become elaborate from age six because of improved spatial relations.
Number sequences learned earlier in life should be prone to SSS, but they are not. Most SS synesthetes report a linear visualization of numbers. But calendars are usually diagrams that reinforce time visualizations. Therefore, time visualization is more common than number visualization.
So next time you know an artist with outstanding memory and even math skills, he might have SSS.
- Price, Mark C. “Toward a Visuospatial Developmental Account of Sequence-Space Synesthesia.” Edited by Beat Meier, Frontiers, Frontiers, 30 Sept. 2013. http://www.frontiersin.org/articles/10.3389/fnhum.2013.00689/full.
- Eagleman, David M. “The Objectification of Overlearned Sequences: A New View of Spatial Sequence Synesthesia.” Egyptian Journal of Medical Human Genetics, Elsevier, 7 July 2009, http://www.sciencedirect.com/science/article/pii/S0010945209002111.
- Ward, Jamie, et al. “The Prevalence and Cognitive Profile of Sequence-Space Synaesthesia.” Egyptian Journal of Medical Human Genetics, Elsevier, 16 Apr. 2018, http://www.sciencedirect.com/science/article/pii/S1053810017305718.