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Skill Level Appropriate for all
- [Jill] Hi, I'm Jill Butler, and this is the Universal Principles of Design, in this movie, Orientation Sensitivity or appealing to the better angles of our nature. In 1931, a young unemployed engineering draftsman by the name of Harry Beck decided to tackle the problem of redesigning the London Underground's rail map. The rail system had grown large and complex over the years and its renderings had become increasingly difficult to comprehend in map form.
Beck realized that since the railway ran mostly underground the physical locations of the stations and other geographic details were irrelevant to the travelers. They couldn't see them. So perhaps drawing on his experience designing electrical circuits, he traded realism for readability, replacing irregular lines with horizontal, vertical, and 45 degree diagonal lines only. The then tweaked the map's scale, placing the stations at equal distances from one another creating a nice balanced composition.
And last but not least, he removed all aboveground details such as city landmarks and street grids. The resulting tube map is a classic of information design, representing one of the first instances of a map designed from a user perspective versus a geographic perspective. The London Underground was initially skeptical of Beck's proposal. It was after all an uncommissioned work by an unemployed engineer that ignored all traditional cartographic conventions.
But to their credit, they decided to test it as a small pamphlet in 1933. It met with great success, and the rest, as they say, is history. Harry Beck's London Underground map is both aesthetically pleasing and easy to read because he intuitively observed a principle of design known as orientation sensitivity. Orientation sensitivity refers to the fact that certain line orientations are more easily processed and discriminated than others.
People can accurately judge vertical and horizontal lines but have problems judging diagonal lines. Lines differing in orientation by more than 30 degrees from a background of lines are easy to detect, but when differing by less than 30 degrees, difficult to detect. But it's not just about visual processing accuracy. It's also about aesthetics. Compositions where the primary elements have vertical or horizontal orientations are considered more aesthetic than diagonal orientations.
So why is this? Orientation sensitivity is based on two phenomena observed in visual perception, the Oblique Effect and the Pop-Out Effect. The Oblique Effect is the ability to more accurately perceive and judge line orientations that are close to vertical and horizontal versus line orientations that are oblique. For example, in tasks where people have to estimate the relative orientation of a line by any number of methods, for example, redrawing from memory, the most accurate judgments are for horizontal and vertical lines, and the least accurate judgments are for oblique lines.
The Pop-Out Effect is the tendency of certain elements in a display to pop out as figure elements, and as a result to be quickly and easily detected. For example, in tasks where people have to identify a target line against a background of lines of a common orientation, the target line is easily detected when it differs from the background lines by 30 degrees or more. Consider orientation sensitivity in compositions requiring discrimination between different lines or textures, or decisions based on the relative position of elements like a radar display.
Facilitate discrimination between linear elements by making their orientation differ by 30 degrees or more. In displays requiring estimates of orientation or angle, provide visual indicators at 30 increments to improve accuracy in oblique regions. Use horizontal and vertical lines as visual anchors to enhance aesthetics and maximize discrimination with oblique elements. So whether you use your knowledge of orientation sensitivity to create easy-to-read gauges and displays, to design more aesthetic graphical patterns and posters, or to produce the next revolutionary leap in cartography remember, horizontal, vertical and 45 degree lines appeal to the better angles of our nature.