People rely on space to represent all types of essentially non-spatial things. For example, most people represent numbers in a spatial manner. Low numbers are pretty consistently associated with left, and right numbers... I'm sorry, high numbers are associated with right. This has been dubbed the mental number line.

You might wonder whether we have a similar representation of time. And indeed we do. Western people perceive time as flowing from left to right. This can be tested by having participants sort a set of cards, which depict some type of temporal progression. For example, participants might be asked to sort a set of photos showing a man of various ages. Sure enough, participants will layout the cards with the young man on the left and the old man on the right.

There is of course nothing inherently left about the past. Presumably, our tendency to associate the past with left stems from the fact that we write from left to right. This left-to-right bias simply transfers to other domains. In a forthcoming paper in Psychological Science, Boroditsky and Gaby show that people from Pormpuraaw, an aboriginal community in Australia, have a very different way of representing time. In the same card sorting-task, Pormpuraawans layout the cards from east to west. Boroditsky and Gaby tested this by having participants perform the task two times and rotating the experimental set-up for the second time. Western participants didn't care about the rotation. Without a compass, most of us are totally disoriented anyway. But Pormpuraawan participants did care. They layed out the cards according to the rotation of the experimental set-up. For example, when they were facing north they arranged the cards from right to left, but when they were facing south they arranged them from left to right. In other words, they maintained an absolute (i.e., north, east, south, west), rather than a relative (i.e., top, right, bottom, left) reference frame. According to the authors, Pormpuraawans derive their spatial reference frame not from writing, as we do, but from the sun (which, in case you were wondering, rises in the east and sets in the west).

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