Objective

  1. Read the two posted papers: Cleveland and McGill, Heer and Bostock.
  2. Write an essay that builds on the above two articles and explores the questions “What do we know about the role of perception in visualization?” and “Why is it important?”
  3. Your essay should include at least 2 additional studies on perception and visualization beyond the assignmed reading.
  4. Cite all sources, no plagurism, and feel free to use images, or your own graphics to make support your thesis.

Perception Essay

As per Cleveland & McGill, Graphical perception is defined as visual decoding of information encoded on graphs.This is linked to the science on how the brain functions and percieves different images and shapes. Based on the perception it then draws an interpretation from it. Different types of charts and graphs are used to communicate the information visually such as pie charts, bar graphs, box plot etc.The article explains that they are certain graphs that are more effecient in conveying the message as the brain reads as the brain interprets the information easily.

Some experiments were conducted to see which graphs are more efficient. It was concluded that visual judgement based on length was bettter than judgement based on area.Similarly diagrams depicting area are preferred over ones depicting volume. These elementary graphical coding are ranked in the following order.

  1. Position
  2. Length
  3. Area
  4. Volume
  5. Shading

The higher the rank the easier it is to decode the information. Various experiments were conducted to verify this result. Hence we can say that data visualization is a science that helps us to convey information visualy such that it can be percieved in the desired manner and with more efficiency.

Zubiaga and Namee have studied more about people’s perception of length as compared to other elementary graphical coding measurements. The results show that the humans have a very high accuracy in reading information through a histogram as compared to other graphs such as density plots, pie charts etc.

Another study by Simkin and Hastie concluded that audience for which the graphs are meant are also critical along with the type of graph used to convey information. Hence the combination of type of graph and type of judgement would determine the speed and accuracy with which the information is percieved. THis was shown through an example where it was proven that comparison was most accurate when judgment required assessing position along a common scale. A similar study, conducted by Spence and Lewandowsky found that pie chart fare well when used in scenarios other than measuring direct magnitude.

References

  1. Cleveland W.S., McGill R. (1989). “Graphical Perception: Theory, Experimentation, and Application to the Development of Graphical Methods”. Journal of the American Statistical Association. 79(387): 521-534.
  2. Heer J., Bostock M. (2010). “Crowdsourcing Graphical Perception: Using Mechanical Turk to Assess Visualization Design”. ACM Human Factors in Computing Systems (CHI). 203-212
  3. Zubiaga, Arkaitz and MacNamee, Brian. (2016) Graphical perception of value distributions : an evaluation of non-expert viewers’ data literacy. Journal of Community Informatics
  4. D. Simkin and R. Hastie. An information-processing analysis of graph perception. J. Am. Stat. Assoc., 82:454–465, Jun 1987
  5. I. Spence and S. Lewandowsky. Displaying proportions and percentages. Applied Cog. Psych., 5:61–77, 1991