The Effect of Graphical Format and Instruction on the Interpretation of Three-Variable Bar and Line Graphs

Conducted by:  Dr David Peebles, July 2009 - September 2010  

Funding: The Higher Education Academy: Psychology Network

This study investigated how graph format, specifically whether a bar or line graph is used, can affect undergraduate psychology students' ability to interpret three-variable 'interaction' data typically found in undergraduate psychology courses.

Consisting of three elements, the project involved two questionnaires separated by a period of 14 days and a 25 minute lecture on graph interpretation. The research revealed that significant differences in data interpretation were produced by graph format in four key subtasks which were; identifying average values of variable levels, finding maximum and minimum values, recognising the main effects and interactions and identifying dependent and independent variables.

These results were interpreted as arising from Gestalt principles of perceptual organisation, that make different aspects of the data more salient and draw users' attention to different variables. 

Based on the results of this experiment, it was argued that, in general, undergraduate psychology students' interpretations of such three-variable interaction data are more accurate when using the bar graph form.

Further details and the final report of the project can be found in the The Higher Education Academy Psychology Network archive