The business origins of the "psychic distance" idiom can be traced back to research conducted by Beckerman (1956) and Linnemann (1966). As a fully formed concept Vahlne and Wiedersheim-Paul (1973) as cited by Nordstrom and Vahlne (1992) described psychic distance as "factors preventing or disturbing the flow of information between potential or actual suppliers and customers." These factors are associated with country-based diversities and dissimilarities and can be grouped into four clear areas:   Although the concept was fully formed by the early 1970s, it was the study of Nordic multinationals by Johanson and Vahlne (1977) which followed on from two earlier studies in 1975 and 1976, that is generally accepted as the concept's real genesis. The studies concluded that a firm's international activities relate directly to psychic distance and that further international expansion progresses into markets with successively greater psychic distance. In summary, companies tend to initially export to countries that they understand; then build on their acquired experience to explore opportunities further afield. In other words, firms enter new markets where they are able to identify opportunities with low market uncertainty then enter markets at successively greater psychic distance. As a consequence, contemporary literature on the internationalisation process cites psychic distance as a key variable and determinant for expansion into foreign markets. The psychic distance has also on occasion been measured through formative indicators such as strong commercial relations, close political relations, historic ties, geographic ties, social ties, country information stock, level of development. These indicators are deeply analyzed for the international market selection. The measurement of these indicators is best accomplished through an index construction. However, the formative indicators are very context dependent. If they were applied to different industries, countries and entry modes, the indicators would have shifted dramatically. More recently, Gairola and Chong incorporated psychic distance to simulate more realistic noise models in spatial games, leading to interesting results, including a manifestation of the psychic distance paradox.