Zohar-Shai and Tzelgov confirmed that our mental number line (MNL) runs from left to right with smaller values to the left. They share that “Several studies . . . have reported [findings indicating] that. . . the ‘mental number line’ extends from left to right. The . . . effect has been found mainly in native speakers of Germanic/Romanic languages; it has been suggested that the . . . effect may derive from the experience of reading from left to right. . . . we provide the first demonstration of a horizontal, left-to-right . . . effect in native speakers of Hebrew. . . . the left-to-right direction of the MNL might reflect a nativistic foundation of such orientation that is independent of cultural factors. Such an interpretation is supported by the findings that indicate a predisposition to represent numerical magnitudes in a left-to-right direction in newborn human babies. . . . 7-month-old infants prefer an increasing left-to-right display of magnitude (de Hevia et al., 2014).” These findings have implications for the display of objects, for example.
Bar Zohar-Shai and Joseph Tzelgov. 2017. “It Does Exist! A Left-to-Right Spatial-Numerical Association of Response Codes (SNARC) Effect Among Native Hebrew Speakers.” Journal of Experimental Psychology: Human Perception and Performance, vol. 43, no. 4, pp. 719-728.