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Fall 2021
In this analysis of six information graphics, I identify their elementary perceptual tasks related to: the information components, the visual variables, and the implantations according to Bertin’s Semiology of Graphics. I abstract certain graphical elements and marks in order to make m rationale clear:
1- Evolution of savings deposits into the Italian post office
– Antonio Gabaglio – 1888
this graph, the informational invariants are the Italian post office and the deposit. The information components are:
A. The total amount of savings deposited into the postal office over time.
B. The average amount per deposit over time.
C. The number of postal savings deposits issued until each period.
Each block represents values for its according month. At a pre-attentive observation, the constant shape and color repeating is associative of the similar kind of information components. Their size variation allows the dissociative and ordered perceptual tasks.
Gabaglio uses the first implantation of point (location) to order the monthly values, following a spiral shape and starting at the center and swirling towards the edge of the circular chart. This ordered layout make it obvious for the quantitative task for time observation, that the location of a block signifies its order in time in relation to the other blocks. It is noteworthy that the spiral layout is not very common, which makes it even more captivating.
The second implantation is the length of each rectangle used to encode the quantitative value of the number of postal savings deposits issued until that period. The rectangles lengths seem to only increase with time suggesting a constant increase in deposits. The third implantation is the height of each rectangle, representing the average amount per deposit.
The area of the rectangle represents then the total amount of savings deposited into the postal office. These dissociative visual variables show variations of shape and allow approximate comparison of the quantitative components at a pre-attentive glance; they can also be calculated through the above-mentioned ratios that Gabaglio includes as a scale/reference for the last block
2- National debts of foreign countries compared with the United States
– Rand McNally – 1890
In this second chart, the informational invariants are the foreign countries, the United States, a person, and a dollar.
The information components are:
A. The total population.
B. The Total debt.
C. The debt per capita.
At a pre-attentive glance, the repetition of the circular shape enables the associative task of the viewer to register that each circle represents a quantitative value. The clumps of circles shape (arbitrarily positioned) allow the viewer the selective task to decode the categories they represent, equidistant groups of equal importance (each country).
The Variation of area is the main implantation enabling the viewer to decode through size, the quantitative relationships among these circles facilitating accurate approximation and comparison.
The color encoding enables the selective perceptual task to focus on one clump at a time (each group of three circles is supposed to be a of a similar color with varying value).
The value and texture encodings enable the selective perceptual task to focus on one circle and the category it represents. This second task requires knowledge from the legend.
Finally, some circles are divided into pie-charts with the use of lines as borders for equidistant micro categories, and areas facilitating quantitative perceptual task.
3- Cholera cases in London
– John Snow – 1954
In this map, the informational invariants are the London urban plan and Cholera sickness. The information component is the quantity of Cholera cases by location.
The implantation of areas enclosed with lines (enable the associative task of identifying the buildings. The positions of these shapes enable the viewer the ordered visual task of identifying the locations of the buildings.
The darker colored rectangles present the viewer with the associative perceptual task of identifying the Cholera cases. The position of these dark rectangles enables the viewer the ordered visual task of identifying their locations.
The heights of the dark rectangles present the viewer with the quantitative perceptual task for the number of cases of Cholera. Enabling comparison and approximation.
This map is beneficial because with these spatial accumulations of larger dark colored rectangles it facilitates the selective and quantitative perceptual tasks to distinguish between agglomerations of Cholera cases and less affected zones.
4- City and rural population
– W.E.B. Du Bois – 1890
In this chart, the informational invariants are the city populations, the rural populations, one person and race. The information component is the Black population.
The distinctive overall shape is a retinal variable that represents one black population in America, despite geographical disparity. It enables the associative task of the similar qualitative attribute represented.
Enabling a selective task, colors enable distinguishing different qualitative categories of black population
(rural / category of city).
Graphically, the implantation of length (size) of each section of the shape encodes the count of the relevant black population, facilitating the quantitative visual task.
On a last note, the spiral is an efficient way to compress length in limited space, the pattern in red is a powerful way to focus the viewer’s attention and to highlight the quantity of the black population in rural areas.
5- Napoleon's Russian campaign-
– Charles Minnard – 1812
In this chart, the informational invariants are the geography, a soldier, the war campaign, and a degree (on the Reamure scale). The information components are:
A - The distance the soldiers traveled.
B- The number of soldiers at a time and place (by subtraction it also shows the casualties). C- The direction of the army’s movement.
D - The location of the army.
E- The temperature during the army’s return from Russia.
F – The duration of the return of the army from Russia.
The shape (as a network of lines) can be identified as representing a flow of soldiers moving across space and time and therefore enables an associative visual task.
The visual variable of position enables the selective perceptual task. The position reflects the geographical location of a point, in fact, the rivers are also represented.
The color enables the selective perceptual task, as it encodes the qualitative attributes of the direction of the army’s travels.
The length of the line is the implantation signifying the distance covered by the soldiers, and therefore enables the quantitative perceptual task; it is aided by the scale on the middle right.
The width of the line encodes the number of soldiers at a certain place, and therefore enables the quantitative perceptual task described in the text accompanying the chart. The width decreasing depicts the casualties.
On the bottom of the flow map, there is a line chart, with a dark colored line, as an implantation enabling the selective perceptual task to read the temperature during the army’s return from Russia.
The y-dimension enables a quantitative perceptual task for the temperature and the x-dimension enables the quantitative task for time in synchronicity with the part of the flow chart representing the army’s return from Russia.
6- The Histomap: Four Thousand Years of World History-
– John B. Sparks – 1931
In this Histomap, the informational invariants are the states, nations, empires, the duration of 50 years and I am guessing a unit to measure power.
The informational component is the rise and decline of different civilization, states, nations, and empires.
The orientation (vertical ranking) of the shape areas enables the associative visual task to identify nation power.
The widths of the areas enable the quantitative task for power and influence of contemporary states, nations, and empires.
The color of each area enables the selective perceptual task as the viewer can distinguish between the influence of the different nations.
The y-dimension enables the quantitative task for time.
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