A reversed map, also known as an Upside-Down map or South-Up map, is a map where south is up, north is down, east is left and west is right. Thus the Southern Hemisphere at the top of the map instead of the bottom. These maps are just as accurate as traditionally oriented maps, because the position of North at the top of maps is arbitrary. Such maps have been made in several cultures and time periods. The convention that North is at the top (and East at the right) on most modern maps was established by the astronomer Ptolemy and was adopted by other cartographers.
In modern times, reversed maps are made as a learning device or to illustrate Northern Hemisphere bias. Different from simply turning a north-up map upside down, a reversed map has the text oriented to be read with south up. Uruguayan constructivist artist Joaquín Torres García created several works depicting a map of South America with the southern point at the top.
The famous "Blue Marble" photograph of the Earth taken from on board Apollo 17 was originally oriented with the south pole at the top, with the island of Madagascar visible just left of center, and the continent of Africa at its right. However, the image was turned upside-down to fit the traditional view.
Reversed maps often have Indonesia placed in the center while Europe and the Americas are placed to the sides, although there are reversed maps centered on the Prime Meridian. Ordinary north-up maps in East Asia also often have the Americas on the right, showing the Pacific ocean whole while cutting through the Atlantic ocean.
The earliest commercially published upside-down map was McArthur's Universal Corrective Map Of The World, published by an Australian Stuart McArthur, in 1979, which sold 350,000 copies and is considered the original.
Psychological significance 
An article by Meier, Moller, Chen, and Riemer-Peltz (2011), published in the journal Social Psychological and Personality Science, explored some of the psychological and behavioral consequences of consistently orienting maps such that north is up, and south is down (i.e., the north-south bias). Across 4 experiments, the authors demonstrated that due to affective associations between vertical position and valence (up = good, down = bad), participants tended to irrationally favor real estate positioned to the north (north=good, south=bad). When an imaginary city map was oriented such that north was at the top of the page, the average participant expressed a preference for living north of that city's center, and guessed that a hypothetical person described as high in socioeconomic status (SES) would also live north of the city's center (whereas someone low in SES would likely live significantly south of the city's center).
In Study 3, one group of participants was shown a map of an imaginary city oriented in the traditional manner (north at the top; south at the bottom); a second group of participants was shown the same map with the orientation reverse (i.e., south at the top; north at the bottom). All participants were asked to place an 'x' on the map where they would prefer to live if moving to this imaginary city. Those in the first group with a traditional orientation, on average, selected a position significantly north of the city's center (replicating Study 2). For the second group shown a map with a reversed orientation (south at the top), there was a nonsignificant trend toward selecting a position south of the city's center. Regardless of orientation, in both groups the trend was for people to prefer a location toward the top of the map, an indication that map orientation may be driving the observed north-south bias.
See also 
- "On maps, why is north always up?". The Straight Dope. 1987-04-24. Retrieved 2007-04-22.
- "Worth a thousand worlds". Geek Trivia (TechRepublic). 2005-12-06. Retrieved 2007-06-23.
- Reversed map centered on the Prime Meridian Flourish.org
- Meier, Brian P.; Moller, Arlen C.; Chen, Julie J.; Riemer-Peltz, Miles (2011). "Spatial Metaphor and Real Estate: North-South Location Biases Housing Preference". Social Psychological and Personality Science 2 (5): 547. doi:10.1177/1948550611401042.
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