Science is learning more about synesthesia. Synesthesia is the condition in which the senses are mixed (e.g., a sound or a number has a color, the sense of touch evokes emotions). There is also a strong time-space synesthesia. According to recent studies by David Brang of UC San Diego, Department of psychology, individuals with time-space synesthesia tend to perceive months of the year in circular shapes, usually just as an image inside their mind's eye.
(Hooper, Rowan. New Scientist Life. 2010. http://www.newscientist.com/article/dn18723-time-lords-discovered-in-california.html)