Tad Brunyé and his colleagues think this spatial bias may have to do with our life-long association of north with up (with additional connotations of being uphill) and south as down - as is the convention on maps.
Brunyé's team tested this idea with a series of implicit association tasks. Student participants from Tufts University in Boston looked at pictures of landscapes and categorised them as either flat or mountainous. They also saw aerial shots of geographic areas and had to indicate whether a star on the picture was located north or south. The main finding here is that the participants were quicker to respond during experimental blocks when the same keyboard response key was used for answering "north" or "mountainous" (and another key was for answering "south" or "flat") compared to the contrasting situation where the same key was used for indicating "north" or "flat" (and another key was for "south" or "mountainous").
This finding suggests that the participants implicitly associated the concepts of "north" and "mountainous" in their minds. The same result was obtained when the images for north vs. south consisted of a large compass in the middle of the screen (with a large N in the centre denoting north or a large S denoting south). Although most Tufts students are from areas outside of Southern New England, where the university is based, the researchers also repeated the study with a student sample based in Ohio, where there are mountains to the south east. Again, despite living in an area where the south is more hilly, the same implicit association of north with hills and mountains was exhibited by the students.
A final study measured participants' implicit associations and their more explicit associations. This latter task came in the form of a free association test - participants were given a word such as "north" or "south" and they had to write the first five words that came to mind (the researchers were interested to see if they'd mention words like "up" or "hilly"; past research has generally found that most people don't explicitly associate the north with a mountainous landscape). This study also involved the participants choosing between pairs of routes through similar terrain to the same destination - one more northerly, one more southerly. Once again the usual bias for southern routes was obtained (these were picked 62 per cent of the time); participants who showed a stronger implicit association of north with mountainous terrain, as revealed on the implicit association test, were more likely to pick the more southerly route.
"Given physical experiences associating upward mobility with relative difficulty, the north-south canonical axis becomes misperceived as indicative of physical effort," the researchers said. "Thus if participants misperceive northward areas as higher elevation (or 'uphill') then it logically follows that they would strategically avoid travelling through what they perceive as relatively demanding areas. Indeed, everyday colloquialisms such as heading down south or going up north may reflect how pervasive such associations are throughout cognition." The researchers added that their finding could have practical implications - for example, affecting driving behaviour within towns and cities and also over greater distances, which could be of interest to city planners and civil engineers.
Tad T. Brunyé, Stephanie A. Gagnon, David Waller, et al (2012). Up north and down south: Implicit associations between topography and cardinal direction. Quarterly Journal of Experimental Psychology : 10.1080/17470218.2012.663393
Post written by Christian Jarrett for the BPS Research Digest.