Cognitive Load Assessment from EEG and Peripheral Biosignals for the Design of Visually Impaired Mobility Aids

Charalampos Saitis,Kyriaki Kalimeri,Mohammad Zavid Parvez

doi:10.1155/2018/8971206

Abstract

Reliable detection of cognitive load would benefit the design of intelligent assistive navigation aids for the visually impaired (VIP). Ten participants with various degrees of sight loss navigated in unfamiliar indoor and outdoor environments, while their electroencephalogram (EEG) and electrodermal activity (EDA) signals were being recorded. In this study, the cognitive load of the tasks was assessed in real time based on a modification of the well-established event-related (de)synchronization (ERD/ERS) index. We present an in-depth analysis of the environments that mostly challenge people from certain categories of sight loss and we present an automatic classification of the perceived difficulty in each time instance, inferred from their biosignals. Given the limited size of our sample, our findings suggest that there are significant differences across the environments for the various categories of sight loss. Moreover, we exploit cross-modal relations predicting the cognitive load in real time inferring on features extracted from the EDA. Such possibility paves the way for the design on less invasive, wearable assistive devices that take into consideration the well-being of the VIP.

Highlights

Visual impairment affects approximately 285 million individuals worldwide according to the WHO [1]
Mean values for outdoor scenes are depicted in the left panel, whereas those for indoor environments are drawn in the right panel
The ERD/ERS index employed for the definition of the classes was averaged over all electrodes; in literature, there are many studies associating specific electrodes to brain functions, for instance, Cz to memory recall tasks; the Emotiv EPOC+ used for the experiments does not provide a full coverage of the cranial surface so as to focus on specific electrodes

Summary

Introduction

Visual impairment affects approximately 285 million individuals worldwide according to the WHO [1]. Assistive navigation aids are essential to the visually impaired (VIP) for improving their quality of life and increase their independence. VIP relied exclusively on the white cane due to its simplicity; despite its reliability in obstacle detection, it does not provide any information regarding important aspects of navigation such as the distance, the speed, or the shortest path to the destination [2]. New technologies came to fill this gap, enhancing the traditional assistive aids, aiming to improve the route planning [3], navigating long distances [4], discovering landmarks [5], and detecting obstacles [6,7,8]. Ranging from smartphone applications to wearable devices, assistive navigation aids promote greater independence and enable VIP to perform tasks formerly impossible or difficult to accomplish [9]. The focus of these aids is often on optimizing way-finding or localization tasks without taking into consideration the individual’s needs [10]

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Conclusion