Perception Essay

Graphical perception is “the ability of viewers to interpret such visual encodings and thereby decode information in graphics.” Crowdsourcing is a new phenomenon which enable web workers complete small tasks. Because crowdsourcing could lower cost and scalability and provides new insights for visualization design, it is very attractive.

The effectiveness of visualization depends on the capabilities of human visual system. Therefore, the data visualization is effective if the intended structure of the data and the perceptual structure of the visualization coincide. The process for the effective data visualization starts with an input data consisting of data elements. The first step of this process is to determine the data structure, namely the relationship between the data elements. The second step is to determine visual elements that represent data elements so that the perceptual structure of the decided visual elements represents the structure of the data. The last step is the layout process which transforms the abstract perceptual structure to a drawable visualization (Dastani, 2002). The following figure shows the process model for effective data visualization.

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The effectiveness of a visualization also depends on other conditions such as conventions, subjective user preferences, cultural settings, and the structural correspondence with its denoting data (Dastani, 2002). For example, temperature values are visualized by color hue values in a temperature map. The effectiveness of visualization for the temperature map increases if red is used for high temperatures and blue is used for low temperatures.

The perception in visualization is very important, because understanding of perception can improve quality and quantity of displayed information (Healey). For example, the multidimensional visualization could assign different visual features to different data attributes. Therefore, multiple data values can be shown in a single image. Visualization could also make the images visually salient. Due to the low-level visual system for humans, researchers especially explored ways in visualization that could remedy people’s visual disadvantages. There’s always an interruption to the image caused usually by a blink. People might be blind to some important area of an image. By utilizing visualization, images could be produced novel for people to direct the eye and then the mind to areas of importance or interest. In addition, color, texture, motion and nonphotorealism have been used in visualization (Healey).

The analysis for the perception in visualization should be based on scientific experiments. The first part is to identify a set of elementary perceptual tasks when people extract quantitive information from graphs. The second is to order the tasked based on the accuracy of people’s performance. The result is that position judgements were more accurate than length judgements and angle judgements. The ordering of the perceptual tasks does not give a complete description about how to make a graph (Cleveland and McGill, 1984).

Citation: Cleveland, W. and McGill, R. (September, 1984). Graphical Perception: Theory, Experimentation, and Application to the Development of Graphical Methods. Journal of the American Statistical Association, Vol. 79, No. 387.

Christopher G. Healey. Healey, C. G. Perception in Visualization. Retrieved from https://www.csc2.ncsu.edu/faculty/healey/PP/

Dastani, M. (March, 2002). The Role of Visual Perception in Data Visualization. Retrieved from http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.109.5971&rep=rep1&type=pdf

Heer, J. and Bostock, M. (2010). Crowdsourcing Graphical Perception: Using Mechanical Turk to Assess Visualization Design