Quantitative Analysis of Mental Effort Investment using Photoplethysmogram

Abstract

Recent studies have shown a close relationship between the mental effort and the photoplethysmograms (PPG), but lack an index which can analyze the invested mental effort quantitatively during the cognitive tasks, which is notable for evaluating user experience in ubiquitous scenarios. In this study, we propose the stress-induced vascular response index (sVRI) to quantify the mental effort invested in cognitive tasks, and verify it via the experiments on aritehmatic tasks with different difficulty levels. The results show an outstanding correlation between the sVRI and the task difficulties, which suggests a dose-response of the sVRI when users perform different cognitive tasks with different difficulties. This is useful for evaluating the user experience in performing cognitive tasks to guide the task or the interaction designs.