Graph Literacy Research Articles

Individual Differences in Graph Literacy: Overcoming Denominator Neglect in Risk Comprehension

ABSTRACTGraph literacy is an often neglected skill that influences decision making performance. We conducted an experiment to investigate whether individual differences in graph literacy affect the extent to which people benefit from visual aids (icon arrays) designed to reduce a common judgment bias (i.e., denominator neglect—a focus on numerators in ratios while neglecting denominators). Results indicated that icon arrays more often increased risk comprehension accuracy and confidence among participants with high graph literacy as compared with those with low graph literacy. Results held regardless of how the health message was framed (chances of dying versus chances of surviving). Findings contribute to our understanding of the ways in which individual differences in cognitive abilities interact with the comprehension of different risk representation formats. Theoretical, methodological, and prescriptive implications of the results are discussed (e.g., the effective communication of quantitative medical data). Copyright © 2011 John Wiley & Sons, Ltd.

Graphical Literacy Moderates the Interaction of Decorative Dimensionality and Cognitive Demand in Computer-Based Graph Comprehension

Scholars have argued that imprecise data graphics, specifically those displaying decorative dimensionality of data, may lead to inaccurate interpretations. Empirical tests of decorative dimensionality have produced mixed results. The literature also suggests that the effects of decorative dimensionality may depend on the cognitive demand of a given task. This study employs an experimental design in which participants receive three levels of decorative dimensionality amidst systematically varying levels of cognitive demand. Graph type and subject matter knowledge are controlled for by design. The hypothesis that the impact of decorative dimensionality on comprehension not only depends on the cognitive demand of the task at hand, but also on the user's graphical literacy, is tested. Results indicate that graphical literacy moderates the interaction between cognitive demand and decorative dimensionality. A familiarity effect may also be present during the display of common two-dimensional bars.

Bar and line graph comprehension: an interaction of top-down and bottom-up processes.

This experiment investigated the effect of format (line vs. bar), viewers' familiarity with variables, and viewers' graphicacy (graphical literacy) skills on the comprehension of multivariate (three variable) data presented in graphs. Fifty-five undergraduates provided written descriptions of data for a set of 14 line or bar graphs, half of which depicted variables familiar to the population and half of which depicted variables unfamiliar to the population. Participants then took a test of graphicacy skills. As predicted, the format influenced viewers' interpretations of data. Specifically, viewers were more likely to describe x-y interactions when viewing line graphs than when viewing bar graphs, and they were more likely to describe main effects and "z-y" (the variable in the legend) interactions when viewing bar graphs than when viewing line graphs. Familiarity of data presented and individuals' graphicacy skills interacted with the influence of graph format. Specifically, viewers were most likely to generate inferences only when they had high graphicacy skills, the data were familiar and thus the information inferred was expected, and the format supported those inferences. Implications for multivariate data display are discussed.

Early Development of Graphical Literacy through Knowledge Building

This study examined growth in graphical literacy for students contributing to an online, multimedia, communal environment as they advanced their understanding of biology, history and optics. Their science and history studies started early in Grade 3 and continued to the end of Grade 4; students did not receive instruction in graphics production, nor were they required to produce graphics. Results show that students spontaneously produced graphics that advanced along seven dimensions, including effective representation of complex ideas, use of source information and captions, and aesthetic quality. On average, the scores for the seven dimensions were higher for Grade 4 students with two years of experience with Knowledge Building pedagogy and technology (Knowledge Forum®) than for Grade 6 students with one year of experience. The overall pattern of results suggests reciprocal enhancement of graphical, textual, digital, and scientific literacy, with students exceeding expectations by available norms, and performance enhanced through extended Knowledge Building experience.

Graph Literacy

Visual displays are often used to communicate important medical information to patients. However, even the simplest graphs are not understood by everyone. To develop and test a scale to measure health-related graph literacy and investigate the level of graph literacy in the United States and Germany. Experimental and questionnaire studies. Setting. Computerized studies in the laboratory and on probabilistic national samples in the United States and Germany. Participants. Nationally representative samples of people 25 to 69 years of age in Germany (n = 495) and the United States (n = 492). Laboratory pretest on 60 younger and 60 older people. Measurements. Psychometric properties of the scale (i.e., reliability, validity, discriminability) and level of graph literacy in the two countries. The new graph literacy scale predicted which patients can benefit from visual aids and had promising measurement properties. Participants in both countries completed approximately 9 of 13 items correctly (in Germany, x¯ = 9.4, s = 2.6; in the United States, x¯ = 9.3, s = 2.9). Approximately one third of the population in both countries had both low graph literacy and low numeracy skills. Limitations. The authors focused on basic graph literacy only. They used a computerized scale; comparability with paper-and-pencil versions should be checked. The new graph literacy scale seems to be a suitable tool for assessing whether patients understand common graphical formats and shows that not everyone profits from standard visual displays. Research is needed on communication formats that can overcome the barriers of both low numeracy and graph literacy.

Who proficts from visual aids: Overcoming challenges in people's understanding of risks

Many people have difficulties grasping numerical concepts that are prerequisites for understanding treatment risk reduction. Visual aids have been proposed as a promising method for enhancing comprehension. In a survey of probabilistic, nationally representative samples in two different countries (United States and Germany), we compared the effectiveness of adding different types of visual aids (icon arrays and bar graphs representing either affected individuals only or the entire population at risk) to the numerical information in either an absolute or a relative risk reduction format. We also analyzed whether people's numeracy and graphical literacy skills affected the efficacy of the visual aids. Our results showed large improvements in accuracy both when icon arrays and when bar graphs were added to numerical information. Highest increases were achieved when the visual aids depicted the entire population at risk. Importantly, visual aids were most useful for the participants who had low numeracy but relatively high graphical literacy skills. Building on previous research showing that problems with understanding numerical information often do not reside in people's minds, but in the representation of the problem, our results show that visual aids help to modify incorrect expectations about treatment risk reduction. Our results have important implications for medical practice.

Debugging strategies and tactics in a multi-representation software environment

This paper investigates the interplay between high level debugging strategies and low level tactics in the context of a multi-representation software development environment (SDE). It investigates three questions. 1. How do programmers integrate debugging strategies and tactics when working with SDEs? 2. What is the relationship between verbal ability, level of graphical literacy and debugging (task) performance. 3. How do modality and perspective influence debugging strategy and deployment of tactics? The paper extends the work of Katz and Anderson [1988. Debugging: an analysis of bug location strategies. Human-Computer Interaction 3, 359–399] and others in terms of identifying high level debugging strategies, in this case when working with SDEs. It also describes how programmers of different backgrounds and degrees of experience make differential use of the multiple sources of information typically available in a software debugging environment. Individual difference measures considered among the participants were their programming experience and their knowledge of external representation formalisms. The debugging environment enabled the participants, computer science students, to view the execution of a program in steps and provided them with concurrently displayed, adjacent, multiple and linked programming representations. These representations comprised the program code, two visualisations of the program and its output. The two visualisations of the program were available, in either a largely textual format or a largely graphical format so as to track interactions between experience and low level mode-specific tactics, for example. The results suggest that (i) additionally to deploying debugging strategies similar to those reported in the literature, participants also employed a strategy specific to SDEs, following execution, (ii) verbal ability was not correlated with debugging performance, (iii) knowledge of external representation formalisms was as important as programming experience to succeed in the debugging task, and (iv) participants with greater experience of both programming and external representation formalisms, unlike the less experienced, were able to modify their debugging strategies and tactics effectively when working under different format conditions (i.e. when working with either largely graphical or largely textual visualisations) in order to maintain their high debugging accuracy level.

Acoustics textbooks of the future

There is likely to be a time when electronic textbooks will have become the norm. If these are essentially free, there will be some distinct advantages for both students and teachers. (Imagine a truly free marketplace of ideas, unaffected by the ploys of textbook publishers.) Electronic resources provide flexibility for adaptation to the organization and level of treatment suitable for particular groups of students. Internal links can be used to remove digressions, fine details, and advanced treatments from the direct line of sight of unsophisticated readers, making it easier to focus on the main ideas. Background materials can be linked to highlighted words, for the benefit of both the students who need them and those who do not. Links among chapters and sections could encourage encyclopedic browsing and the development of a cross-linked structure of understanding. Multimedia resources have an obvious relevance to acoustics in the form of audio examples. Kinetic, interactive figures could play an important role by encouraging the development of graphical literacy, coupled with the more widely recognized verbal and mathematical literacies needed for scientific work. MERLOT and other existing models for the development of electronic textbooks will be discussed. [Work supported by the Paul S. Veneklasen Research Foundation.]

Review of Graph Comprehension Research: Implications for Instruction

Graphs are commonly used in textbooks and educational software, and can help students understand science and social science data. However, students sometimes have difficulty comprehending information depicted in graphs. What makes a graph better or worse at communicating relevant quantitative information? How can students learn to interpret graphs more effectively? This article reviews the cognitive literature on how viewers comprehend graphs and the factors that influence viewers' interpretations. Three major factors are considered: the visual characteristics of a graph (e.g., format, animation, color, use of legend, size, etc.), a viewer's knowledge about graphs, and a viewer's knowledge and expectations about the content of the data in a graph. This article provides a set of guidelines for the presentation of graphs to students and considers the implications of graph comprehension research for the teaching of graphical literacy skills. Finally, this article discusses unresolved questions and directions for future research relevant to data presentation and the teaching of graphical literacy skills.

An evaluation of the graphical literacy of Annals of Emergency Medicine

Study Objective: To describe the type, quantity, and quality of graphics used to present original research in Annals of Emergency Medicine.Methods: We performed a blinded, retrospective review of all graphics published in Annals of Emergency Medicine’s original research articles from January 1998 through June 1999. We assessed the types of graphics, the use of special features to display detail, the clarity of each graphic, discrepancies within the graphic or between the graphic and text, and the efficiency of data presentation. Results: Forty-six percent (68/147) of original research communications contained at least 1 graphic. Of the 128 graphics in these 68 articles, simple univariate displays predominated (53%). Only one third of graphics displayed by-subject data through the use of one-way plots, scatter plots, or other formats. Graphics generally defined all symbols and abbreviations (99%) and were self-explanatory (88%). Techniques for conveying the richness of a data set were seldom used (11% of all graphics). Forty percent (51/128) of the graphics contained internal contradictions (15%), muddled displays (19%), numeric distortion (5%), nonstandard graphing conventions (7%), and other lapses in design or execution. Inefficiencies of data presentation included internal redundancy (16%), extraneous decoration (10%), and redundancy of graphic data with other text/tables (15%). Conclusion: The majority of graphics in Annals of Emergency Medicine, although internally valid, failed to take full advantage of the graphic’s potential and often depicted summary data when portrayal of subject-specific data was possible. To help readers fully understand research findings, authors and editors should take care to ensure that graphics efficiently and effectively portray the optimal amount of information. [Cooper RJ, Schriger DL, Tashman DA. An evaluation of the graphical literacy of Annals of Emergency Medicine. Ann Emerg Med. January 2001;37:13-19.]

Achieving graphical excellence: suggestions and methods for creating high-quality visual displays of experimental data.

Graphics are an important means of communicating experimental data and results. There is evidence, however, that many of the graphics printed in scientific journals contain errors, redundancies, and lack clarity. Perhaps more important, many graphics fail to portray data at an appropriate level of detail, presenting summary statistics rather than underlying distributions. We seek to aid investigators in the production of high-quality graphics that do their investigations justice by providing the reader with optimum access to the relevant aspects of the data. The depiction of by-subject data, the signification of pairing when present, and the use of symbolic dimensionality (graphing different symbols to identify relevant subgroups) and small multiples (the presentation of an array of similar graphics each depicting one group of subjects) to portray stratification are stressed. Step-by-step instructions for the construction of high-quality graphics are offered. We hope that authors will incorporate these suggestions when developing graphics to accompany their manuscripts and that this process will lead to improvements in the graphical literacy of scientific journals. We also hope that journal editors will keep these principles in mind when refereeing manuscripts submitted for peer review.