Pupillary Responses for Cognitive Load Measurement to Classify Difficulty Levels in an Educational Video Game: Empirical Study.

Hugo Mitre-Hernandez,Roberto Covarrubias Carrillo,Carlos Lara-Alvarez

doi:10.2196/21620

Abstract

BackgroundA learning task recurrently perceived as easy (or hard) may cause poor learning results. Gamer data such as errors, attempts, or time to finish a challenge are widely used to estimate the perceived difficulty level. In other contexts, pupillometry is widely used to measure cognitive load (mental effort); hence, this may describe the perceived task difficulty.ObjectiveThis study aims to assess the use of task-evoked pupillary responses to measure the cognitive load measure for describing the difficulty levels in a video game. In addition, it proposes an image filter to better estimate baseline pupil size and to reduce the screen luminescence effect.MethodsWe conducted an experiment that compares the baseline estimated from our filter against that estimated from common approaches. Then, a classifier with different pupil features was used to classify the difficulty of a data set containing information from students playing a video game for practicing math fractions.ResultsWe observed that the proposed filter better estimates a baseline. Mauchly’s test of sphericity indicated that the assumption of sphericity had been violated (χ214=0.05; P=.001); therefore, a Greenhouse-Geisser correction was used (ε=0.47). There was a significant difference in mean pupil diameter change (MPDC) estimated from different baseline images with the scramble filter (F5,78=30.965; P<.001). Moreover, according to the Wilcoxon signed rank test, pupillary response features that better describe the difficulty level were MPDC (z=−2.15; P=.03) and peak dilation (z=−3.58; P<.001). A random forest classifier for easy and hard levels of difficulty showed an accuracy of 75% when the gamer data were used, but the accuracy increased to 87.5% when pupillary measurements were included.ConclusionsThe screen luminescence effect on pupil size is reduced with a scrambled filter on the background video game image. Finally, pupillary response data can improve classifier accuracy for the perceived difficulty of levels in educational video games.

Highlights

Overview An educational video game (EVG) is a video game that provides learning or training value to the player
The screen luminescence effect on pupil size is reduced with a scrambled filter on the background video game image
The results show that there was a significant difference between mean pupil diameter change (MPDC) estimated from different baseline images (F5,78=30.965; P

Summary

Introduction

Overview An educational video game (EVG) is a video game that provides learning or training value to the player. Some of the effective features of educational video games include a clear goal, an adequate level of difficulty, quick-moving stimuli, and integrated instructions [3]. Our research focuses on the cognitive load (mental effort) generated by reasoning tasks [6] about math fractions; this is a direct way to measure the difficulty perceived by the EVG's player. Studying how to set an adequate difficulty level has attracted particular attention in the educational video games field [7,8]. A learning task recurrently perceived as easy (or hard) may cause poor learning results Gamer data such as errors, attempts, or time to finish a challenge are widely used to estimate the perceived difficulty level. B1 → d1 are states of anxiety that demand new learning skills to return to optimal flow. B2 → d2 are states of boredom that need more challenges to return to optimal flow

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Discussion

Conclusion