Elsevier

Neurocomputing

Volume 444, 15 July 2021, Pages 390-398
Neurocomputing

Deep-learning-based reading eye-movement analysis for aiding biometric recognition

https://doi.org/10.1016/j.neucom.2020.06.137Get rights and content

Abstract

Eye-movement recognition is a new type of biometric recognition technology. Without considering the characteristics of the stimuli, the existing eye-movement recognition technology is based on eye-movement trajectory similarity measurements and uses more eye-movement features. Related studies on reading psychology have shown that when reading text, human eye-movements are different between individuals yet stable for a given individual. This paper proposes a type of technology for aiding biometric recognition based on reading eye-movement. By introducing a deep-learning framework, a computational model for reading eye-movement recognition (REMR) was constructed. The model takes the text, fixation, and text-based linguistic feature sequences as inputs and identifies a human subject by measuring the similarity distance between the predicted fixation sequence and the actual one (to be identified). The experimental results show that the fixation sequence similarity recognition algorithm obtained an equal error rate of 19.4% on the test set, and the model obtained an 86.5% Rank-1 recognition rate on the test set.

Introduction

Biometric recognition technology is widely used in e-commerce, electronic products, and network security. Reading eye-movement is a human behavior with the biometric characteristics of convenience, security, universality and collectability [1]. Thus, users can be identified by comparing human eye-movement trajectories.

Based on measurements of eye-movement trajectory similarity, the existing eye-movement recognition technology extracts the measurable features of the eye-movement trajectory, including the fixation duration and the lengths of the saccades. Other technologies compare the eye-movement trajectories using more complicated space and time information of the eye-movement. The existing technologies are usually used to obtain the similarity measurement value (or values) of eye-movement trajectories. However, the characteristics of the stimuli are not considered.

Related studies on reading psychology have shown that human eye-movements during reading are significantly different between individuals [2], [3], [4], but the same individual exhibits a certain similarity. This suggests that human eye-movement is unique and stable to some extent and can be used in biometrics [5], [6]. Fig. 1 shows the fixation sequences as ten subjects read the same text.

In this study, multiple-input deep neural networks were utilized to learn the reading eye-movement behaviors and construct a computational model for reading eye-movement recognition (REMR). The model can learn the features of the stimuli (reading materials) and the eye-movement trajectory. The model can fully simulate human eye-movement after training and can be applied for user identification by comparing the predicted and actual (to be identified) fixation sequences. Combined with other biometric recognition technologies, this technology can be used as a supplementary tool for the existing identity authentication methods to realize multi-factor identity authentication.

The main contributions of the present paper are as follows.

  • 1.

    A biometric recognition technology is proposed based on reading eye-movement. Accounting for the stimuli (reading materials) and scanning path, this technology uses fewer handcrafted features to obtain effective recognition by utilizing the deep-learning characteristics of automatic feature extraction. As a result, the model obtained an 86.5% Rank-1 recognition accuracy on the test set.

  • 2.

    A REMR computational model based on deep-learning is proposed. This model uses a deep neutral network to generate the predicted fixation sequence and measure the similarity distance between the predicted and actual fixation sequences to identify the subject.

  • 3.

    An algorithm is presented for evaluating the fixation sequence similarity. The algorithm uses dynamic time warping (DTW) to measure the similarity between two fixation sequences, and the proposed algorithm obtained an equal error rate (EER) of 19.4% on the test set.

Section snippets

Related work

The biometric study of eye-movement stems from the early study of scanpath theory, in which the word “scanpath” refers to the space path formed by an orderly fixation and saccadic sequence. In 1971, Noton and Stark [7] found that the general scanpath followed by a subject during the first viewing of a pattern was repeated in the initial eye-movements of roughly 65% of subsequent viewings, and the scanpath for specific stimuli varied from person to person.

The 2004 paper by Kasprowski and Ober [8]

Problem setting

Experimental results of eye-movement and reading have indicated that eye-movement during reading is goal-oriented and discrete [4]. This means that the saccade is non-random in selecting a visual target and that the saccade target points to a particular word rather than a specific distance. Based on this notion, there are many candidate words in the latent saccade period, and each word has a chance to be selected as the target of subsequent saccades. In this work, the probability of each word

Experimental environment and dataset

The experimental environment was Python3.7 + Keras2.2.4 + TensorFlow1.13. All the code was released on GitHub at https://github.com/wxmgo/eye_movement_in_reading/. In addition to being interesting to readers in the fields of biometrics and machine learning, the public posting of the code on Github will allow others to easily utilize or modify this method for their own problems.

We obtained the dataset from the Provo Corpus [34]. The corpus is open and can be downloaded from the Open Science

Evaluation metric

The proposed method was evaluated by the Rank-1 (R1) accuracy rate and the equal error rate (EER). The Rank-1 accuracy rate is the ratio of the total number of correct recognitions to the number of samples. The EER is the value when the false acceptance rate (FAR) and the false rejection rate (FRR) are equal.

The false acceptance rate is the ratio that is considered to be the same subject when the similarity distance of different eye-movement sequences is greater than the given threshold during

Conclusion

In this paper, a type of reading eye-movement biometric recognition technology was proposed based on deep-learning. This technology constructs a reading eye-movement recognition (REMR) computational model based on a multi-input deep neural network and identifies human subjects by comparing the predicted and actual fixation sequences. This model is less dependent on the data features and requires less pre-possessing, which makes it attractive for industrial and engineering applications [42]. The

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

This work was supported by the National Natural Science Foundation of China [grant number 61871326], the Humanities and Social Science Fund of Ministry of Education of China [grant number 18YJCZH180] , the Natural Science Foundation of Shaanxi Province [grant number 2018JM6116], the Social Science Foundation of Shaanxi Province [grant number 2019M001] , and the Aeronautical Science Foundation of China [grant number 20185153].

Xiaoming Wang received the Ph.D. degree from Northwestern Polytechnical University, Xi'an, China, in 2020. He is currently an Associate Professor with Xi'an International Studies University. His research interests include cognitive computing and artificial intelligence.

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  • Xiaoming Wang received the Ph.D. degree from Northwestern Polytechnical University, Xi'an, China, in 2020. He is currently an Associate Professor with Xi'an International Studies University. His research interests include cognitive computing and artificial intelligence.

    Xinbo Zhao received the Ph.D. degree from the Northwestern Polytechnical University, Xi’an, China, in 2003. Currently, he is a professor at the School of Computer Science, Northwestern Polytechnical University. His interests include image processing, computer vision, pattern recognition and artificial intelligence. He is the author or co-author of more than 100 scientific papers.

    Yanning Zhang received her B.S. degree from Dalian University of Science and Engineering in 1988, M.S. and Ph.D. Degree from Northwestern Polytechnical University in 1993 and 1996 respectively. She is presently a Professor of School of Computer Science and Technology, Northwestern Polytechnical University. She is also the organization chair of ACCV2009 and the publicity chair of ICME2012. Her research work focuses on signal and image processing, computer vision and pattern recognition. She has published over 200 papers in these fields, including the ICCV2011 best student paper. She is a member of IEEE.

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