Experimental Methodology for the Evaluation of the 3D Visualization of Quantitative Information: a Case Study Concerning SEEG Information

Abstract

The visual analysis of Stereoeletroencephalographic (SEEG) signals in their anatomical context is aimed at understanding the spatio-temporal dynamics of epileptic processes. The magnitude of these signals may be encoded by graphical glyphs, having a direct impact on the perception of the values. This problem has motivated an evaluation of the quantitative visualization of these signals, specifically with regard to the influence of the coding scheme of the glyphs on the understanding and analysis of the signals. This work describes an experiment conducted with human observers in order to evaluate three different coding schemes used to visualize the magnitude of SEEG signals in their 3D anatomical context. Before the experiment we had no clue to which of these schemes would provide better performance to the human observers, while the literature offered theories supporting different answers. Through our experiment we intended to find out if any of these coding schemes allows better performance in two aspects: accuracy and speed. A protocol has been developed to measure these aspects. The results presented in this work were obtained from 40 human observers. Comparison between the three coding schemes was first performed through an Exploratory Data Analysis (EDA). Statistical significance of this comparison was then established using nonparametric methods. Influence of some other factors on the observers’ performance was also investigated.