Low-cost Eye Research Articles

Low-Cost Eye Gesture Communication System for People with Motor Disabilities

Current eye-tracking input systems for people with ALS or other motor impairments are expensive, not robust under sunlight, and require frequent re-calibration and substantial, relatively immobile setups. Eye-gaze transfer (e-tran) boards, a low-tech alternative, are challenging to master and offer slow communication rates. To mitigate the drawbacks of these two status quo approaches, we created Gaze Speak, an eye gesture communication system that runs on a smartphone, and is designed to be low-cost, robust, portable, and easy-to-learn, with a higher communication bandwidth than an e-tran board. Gaze Speak can interpret eye gestures in real time, decode these gestures into predicted utterances, and facilitate communication, with different user interfaces for speakers and interpreters. Our evaluations demonstrate that GazeSpeak is robust, has good user satisfaction, and provides a speed improvement with respect to an e-tran board; we also identify avenues for further improvement to low-cost, low-effort gaze-based communication technologies.

Evaluating the performance of gaze interaction for map target selection

ABSTRACT The eye tracking approach has the potential to facilitate more tailored and intelligent geoapplication interactions. There is a lack of knowledge regarding how gaze interaction influences user performance (accuracy and efficiency), visual behavior, and cognitive workload in real-world map-reading settings. In this study, we adopted a low-cost eye tracker and dwell time method to implement a fundamental gaze-based map interaction: target (point, line and area) selection. We administered a comparative experiment in which 36 participants were asked to perform a series of map target selection tasks using gaze-based and mouse interactions. The results demonstrated that gaze-based map interaction is comparable to mouse in terms of overall efficiency. By evaluating the visual behavior of the participants, we found that mouse interaction exhibited heightened fixation frequency and larger saccade amplitude than gaze interaction. Although gaze-based map interaction frustrated participants more often, the overall cognitive workload was no different from that of mouse interaction. These differences between interaction modes were largely affected by task types but rarely dependent on target shapes or positions. Moreover, participants evaluated gaze interaction higher in terms of attractiveness, stimulation and novelty. These results are beneficial for map interaction researchers and developers.

Evaluating the Usability of a Gaze-Adaptive Approach for Identifying and Comparing Raster Values between Multilayers

Raster maps provide intuitive visualizations of remote sensing data representing various phenomena on the Earth’s surface. Reading raster maps with intricate information requires a high cognitive workload, especially when it is necessary to identify and compare values between multiple layers. In traditional methods, users need to repeatedly move their mouse and switch their visual focus between the map content and legend to interpret various grid value meanings. Such methods are ineffective and may lead to the loss of visual context for users. In this research, we aim to explore the potential benefits and drawbacks of gaze-adaptive interactions when interpreting raster maps. We focus on the usability of the use of low-cost eye trackers on gaze-based interactions. We designed two gaze-adaptive methods, gaze fixed and gaze dynamic adaptations, for identifying and comparing raster values between multilayers. In both methods, the grid content of different layers is adaptively adjusted depending on the user’s visual focus. We then conducted a user experiment by comparing such adaptation methods with a mouse dynamic adaptation method and a traditional method. Thirty-one participants (n = 31) were asked to complete a series of single-layer identification and multilayer comparison tasks. The results indicated that although gaze interaction with adaptive legends confused participants in single-layer identification, it improved multilayer comparison efficiency and effectiveness. The gaze-adaptive approach was well received by the participants overall, but was also perceived to be distracting and insensitive. By analyzing the participants’ eye movement data, we found that different methods exhibited significant differences in visual behaviors. The results are helpful for gaze-driven adaptation research in (geo)visualization in the future.

Virtual reality eye exercises application based on bates method: a preliminary study

In many situations, ophthalmologists prescribe glasses and contact lenses as a treatment method for Myopia. The other way to cure myopia is by performing Lasik surgery or using advanced tools which takes a large amount of financial effort. Dr. William Horatio Bates proposed a promising method to cure myopia with an eye exercise approach, providing opportunities to enhance the availability of low-cost eye treatment that is not easily achievable with surgery and other expensive approaches. However, many myopia patients are still unaware of this method and have no idea how to use it in their daily lives. The rapid growth of virtual reality (VR) technology has shown that this technology offers an affordable and effective solution to provide better health services. This paper expands the result of an initial experiment aimed to validate the utilization of mobile VR technology to enhance the possibility of the Bates method implementation as a low-cost daily eye exercise tool. A direct diary study with 14 participants was carried out to explicitly investigate the feasibility of the proposed app. The result reveals that the proposed app could assist people with myopia when doing eye exercises and the result is quite promising in reducing the refractive levels with 0.13 diopter on average within 5 weeks period.

An Effective Algorithm to Analyze the Optokinetic Nystagmus Waveforms from a Low-Cost Eye Tracker.

Objective: Most neurological diseases are usually accompanied by changes in the oculomotor nerve. Analysis of different types of eye movements will help provide important information in ophthalmology, neurology, and psychology. At present, many scholars use optokinetic nystagmus (OKN) to study the physiological phenomenon of eye movement. OKN is an involuntary eye movement induced by a large moving surrounding visual field. It consists of a slow pursuing eye movement, called “slow phase” (SP), and a fast re-fixating saccade eye movement, called “fast phase” (FP). Non-invasive video-oculography has been used increasingly in eye movement research. However, research-grade eye trackers are often expensive and less accessible to most researchers. Using a low-cost eye tracker to quantitatively measure OKN eye movement will facilitate the general application of eye movement research. Methods & Results: We design an analytical algorithm to quantitatively measure OKN eye movements on a low-cost eye tracker. Using simple conditional filtering, accurate FP positions can be obtained quickly. The high-precision FP recognition rate is of great help for the subsequent calculation of eye movement analysis parameters, such as mean slow phase velocity (MSPV), which is beneficial as a reference index for patients with strabismus and other eye diseases. Conclusions: Experimental results indicate that the proposed method achieves faster and better results than other approaches, and can provide an effective algorithm to calculate and analyze the FP position of OKN waveforms.

A low-cost, high-performance video-based binocular eye tracker for psychophysical research.

We describe a high-performance, pupil-based binocular eye tracker that approaches the performance of a well-established commercial system, but at a fraction of the cost. The eye tracker is built from standard hardware components, and its software (written in Visual C++) can be easily implemented. Because of its fast and simple linear calibration scheme, the eye tracker performs best in the central 10 degrees of the visual field. The eye tracker possesses a number of useful features: (1) automated calibration simultaneously in both eyes while subjects fixate four fixation points sequentially on a computer screen, (2) automated realtime continuous analysis of measurement noise, (3) automated blink detection, (4) and realtime analysis of pupil centration artifacts. This last feature is critical because it is known that pupil diameter changes can be erroneously registered by pupil-based trackers as a change in eye position. We evaluated the performance of our system against that of a wellestablished commercial system using simultaneous measurements in 10 participants. We propose our low-cost eye tracker as a promising resource for studies of binocular eye movements.

Custom on-axis head-mounted eye tracker for 3D active glasses

Currently, no low cost commercial 3D active glasses with embedded eye tracker are available despite the importance of 3D and eye tracking for numerous applications. In this context, a simple low cost eye tracker for 3D glasses with liquid crystal shutters is presented and tested for orthoptics applications. By using a beam splitter to better align the camera with the line of sight when the subject looks at a target in front of him at far range, the new design allows recording high quality images with limited pupil deformation when compared to other commercial eye trackers where the cameras can be far from this axis (head mounted or fixed). Such a design could be useful for various applications from orthoptics to virtual reality

Evaluating low-cost eye movement recording apparatuses for effective student practice

Evaluating low-cost eye movement recording apparatuses for effective student practice

A Fast and Effective System for Analysis of Optokinetic Waveforms with a Low-Cost Eye Tracking Device.

Optokinetic nystagmus (OKN) is an involuntary eye movement induced by motion of a large proportion of the visual field. It consists of a “slow phase (SP)” with eye movements in the same direction as the movement of the pattern and a “fast phase (FP)” with saccadic eye movements in the opposite direction. Study of OKN can reveal valuable information in ophthalmology, neurology and psychology. However, the current commercially available high-resolution and research-grade eye tracker is usually expensive. Methods & Results: We developed a novel fast and effective system combined with a low-cost eye tracking device to accurately quantitatively measure OKN eye movement. Conclusions: The experimental results indicate that the proposed method achieves fast and promising results in comparisons with several traditional approaches.

Evaluating the data quality of the Gazepoint GP3 low-cost eye tracker when used independently by study participants.

The portability of low-cost eye trackers makes them attractive for research outside of the laboratory. Such research may require independent eye-tracker use. The present work compared the data quality of the Gazepoint GP3 when used independently by research participants with expert eye-tracking users. Twenty participants completed a training and a testing session 1 week apart. At training visits, participants were taught how to set up and use eye-tracking hardware and software and how to complete two tasks: a calibration task to measure accuracy and precision, as well as a visual search task to assess target fixations. At the testing session, participants set up the Gazepoint eye tracker and completed the two tasks without assistance. Participant accuracy and precision and visual search performance were compared to values obtained from two expert eye-tracking users. Additionally, the eye-tracker sampling rate, which is sensitive to factors such as head motion, was assessed in both participants and the expert users. Participant accuracy and precision closely approximated expert user values. Participant target fixations were detected with a 92.5% sensitivity and 76.8% specificity, closely mirroring expert user sensitivity and specificity. The sampling rate distribution was also similar between the participants and expert user (the means of those distributions were 16.99 ± 3.0 ms and 16.43 ± 2.3 ms, respectively). When used independently, data quality obtained from a low-cost, portable eye-tracking setup closely approximated values obtained from an expert user and was adequate enough to be a feasible option for some studies that require independent use by study participants.

Automatic pupil detection and gaze estimation using the vestibulo-ocular reflex in a low-cost eye-tracking setup

Automatic eye tracking is of interest for interaction with people suffering from amyotrophic lateral sclerosis, for using the eyes to control a computer mouse, and for controlled radiotherapy of uveal melanoma. It has been speculated that gaze estimation accuracy might be improved by using the vestibulo-ocular reflex. This involuntary reflex results in slow, compensatory eye movements, opposing the direction of head motion. We therefore hypothesised that leaving the head to move freely during eye tracking must produce more accurate results than keeping the head fixed, only allowing the eyes to move. The purpose of this study was to create a low-cost eye tracking system that incorporates the vestibulo-ocular reflex in gaze estimation, by keeping the head freely moving. The instrument used comprised a low-cost head-mounted webcam which recorded a single eye. Pupil detection was fully automatic and in real time with a straightforward hybrid colour-based and model-based algorithm, despite the lower-end webcam used for recording and despite the absence of direct illumination. A model-based algorithm and an interpolation-based algorithm were tested in this study. Based on mean absolute angle difference in the gaze estimation results, we conclude that the model-based algorithm performed better when the head was not moving and equally well when the head was moving. With most deviations of the points of gaze from the target points being less than 1° using either algorithm when the head is moving freely, it can be concluded that our setup performs fully within the 2° benchmark from literature, whereas deviations when the head was not moving exceeded 2°. The algorithms used were not previously tested under passive illumination. This was the first study of a low-cost eye-tracking setup taking into account the vestibulo-ocular reflex.

Can a Low-Cost Eye Tracker Assess the Impact of a Valent Stimulus? A Study Replicating the Visual Backward Masking Paradigm

AbstractCapturing affective response to valent stimuli using eye tracking is of interest not only to academic research but also to commercial equipment developers (e.g. car dashboards). In order to investigate whether a low-cost eye tracker can effectively detect participants’ physiological response to negatively valent stimuli, 44 participants aged 19–24 (mean = 24.7, SD = 5.8) were recruited to complete the visual backward masking paradigm in a repeated-measure experimental design. Saccadic duration and pupil sizes were recorded using a lower-end 60-Hz tracker. Data was analysed using a mix of parametric and non-parametric tests. Our results suggest that valence in the form of fearful vs neutral faces has a significant main effect on both saccadic duration [V = 931, P < 0.001, d = 0.96] and pupil size [t(43) = 29.81, P < 0.001, d = 3.91)]. Our findings were further supported by Bayes factor analysis, which showed that saccadic duration data was 24 times more likely to occur, and pupil size measurement data was 89 times more likely, under the alternative hypothesis, showing that differences in valence had a main effect. The combined evidence produced by our Bayesian analysis, the large effect sizes of our frequentist analysis and the significant effect on two separate measurements lead us to suggest that, under the right conditions, low-cost eye trackers can successfully detect changes in saccadic duration and pupil sizes as a result of physiological responses to threat-relevant visual stimuli.

Development of Low-Cost Vision-based Eye Tracking Algorithm for Information Augmented Interactive System

Development of Low-Cost Vision-based Eye Tracking Algorithm for Information Augmented Interactive System

Deep Neural Networks for Low-Cost Eye Tracking

Abstract The paper presents a detailed analysis of modern techniques that can be used to track gaze with a webcam. We present a practical implementation of the most popular methods for tracking gaze. Various models of deep neural networks that can be involved in the process of online gaze monitoring are reviewed. We introduce a new eye-tracking approach where the effectiveness of using a deep learning method is significantly increased. Implementation is in Python where its application is demonstrated by controlling interaction with the computer. Specifically, a dual coordinate system is given for controlling the computer with the help of a gaze. The first set of coordinates-the position of the face relative to the computer, is implemented by detecting color from the infrared LED via the OpenCV library. The second set of coordinates-giving gaze position-is obtained via the YOLO (v3) package. A method of labeling the eyes is given, in which 3 objects are used to track gaze (to the left, to the right, and in the center).

Developing a visual perimetry test based on eye-tracking: proof of concept

Computerized Perimetry (CP) is one of the clinical tests commonly used to evaluate peripheral vision and monitor the progress of eye diseases such as glaucoma. The aim of CP is to determine retinal sensitivity using luminous stimuli of variable intensity at different positions of the visual field. In modern campimetry devices, patients must respond to each perceived stimulus by pressing a button; however, this characteristic makes the test more susceptible to spurious and erroneous interpretations due to tiredness, lack of concentration, or device design flaws. This work presents an alternative paradigm for automatically assessing stimulus perception through a low-cost eye tracker and a computer monitor. We tested the preliminary version of the paradigm among eight subjects and obtained favorable results. In conclusion, our eye-tracking paradigm tool could help design more reliable visual field tests using low-cost portable equipment.

Low Cost Eye Tracking: Ready for Individual Differences Research?

The recent availability of low cost of eye tracking hardware provides researchers a fruitful opportunity to collect additional human subject data for under $700. This current study sought to investigate whether low-cost eye tracking is capable of replicating a large effect showing a relationship between resting pupil size and working memory capacity. Seventy-nine Navy and Marine Corps student pilots participated in this study and granted access to their aviation selection test scores. The study demonstrated the capability of the Gazepoint GP3 system to detect the pupillary light reflex within every participant. However, in contrast to findings from other researchers, analyses revealed a negative correlation between resting pupil size and partial Operation Span scores and no correlation between resting pupil size and two cognitive components of the aviation selection test. These findings, in addition to other reasons discussed herein, suggest that the Gazepoint GP3 system’s millimeter pupil size measurements should not be used in isolation to compare values between individuals. They also suggest the need for further investigation of the relationship between baseline pupil size and working memory capacity.

Measuring the Spatial Noise of a Low-Cost Eye Tracker to Enhance Fixation Detection

The present study evaluates the quality of gaze data produced by a low-cost eye tracker (The Eye Tribe©, The Eye Tribe, Copenhagen, Denmark) in order to verify its suitability for the performance of scientific research. An integrated methodological framework, based on artificial eye measurements and human eye tracking data, is proposed towards the implementation of the experimental process. The obtained results are used to remove the modeled noise through manual filtering and when detecting samples (fixations). The outcomes aim to serve as a robust reference for the verification of the validity of low-cost solutions, as well as a guide for the selection of appropriate fixation parameters towards the analysis of experimental data based on the used low-cost device. The results show higher deviation values for the real test persons in comparison to the artificial eyes, but these are still acceptable to be used in a scientific setting.

Enhancing the usability of low-cost eye trackers for rehabilitation applications.

Eye tracking is one of the most widely used technique for assessment, screening and human-machine interaction related applications. There are certain issues which limit the usage of eye trackers in practical scenarios, viz., i) need to perform multiple calibrations and ii) presence of inherent noise in the recorded data. To address these issues, we have proposed a protocol for one-time calibration against the “regular” or the “multiple” calibration phases. It is seen that though it is always desirable to perform multiple calibration, the one-time calibration also produces comparable results and might be better for individuals who are not able to perform multiple calibrations. In that case, “One-time calibration” can also be done by a participant and the calibration results are used for the rest of the participants, provided the chin rest and the eye tracker positions are unaltered. The second major issue is the presence of the inherent noise in the raw gaze data, leading to systematic and variable errors. We have proposed a signal processing chain to remove these two types of errors. Two different psychological stimuli-based tasks, namely, recall-recognition test and number gazing task are used as a case study for the same. It is seen that the proposed approach gives satisfactory results even with one-time calibration. The study is also extended to test the effect of long duration task on the performance of the proposed algorithm and the results confirm that the proposed methods work well in such scenarios too.

Detecting drivers’ cognitive load from saccadic intrusion

In this paper, we have explored use of Saccadic Intrusion to detect drivers’ cognitive load and instantaneous perception of developing road hazards. Saccadic Intrusion is a type of eye gaze movement which was earlier found to be related to change in cognitive load. We have developed an algorithm to detect saccadic intrusion from a commercially available low-cost eye gaze tracker and conducted four user studies involving a driving simulator and cognitive and hazard perception tests. Our results show that average velocities of saccadic intrusion increases with increase in cognitive load and recording saccadic intrusion and eye blinks for 6 s duration can predict drivers’ instantaneous perception of developing road hazards.

An analysis of the suitability of a low-cost eye tracker for assessing the cognitive load of drivers

This paper presents a driving simulator study in which we investigated whether the Eye Tribe eye tracker (ET) is capable of assessing changes in the cognitive load of drivers through oculography and pupillometry. In the study, participants were asked to drive a simulated vehicle and simultaneously perform a set of secondary tasks with different cognitive complexity levels. We measured changes in eye properties, such as the pupil size, blink rate and fixation time. We also performed a measurement with a Detection Response Task (DRT) to validate the results and to prove a steady increase of cognitive load with increasing secondary task difficulty. The results showed that the ET precisely recognizes an increasing pupil diameter with increasing secondary task difficulty. In addition, the ET shows increasing blink rates, decreasing fixation time and narrowing of the attention field with increasing secondary task difficulty. The results were validated with the DRT method and the secondary task performance. We conclude that the Eye Tribe ET is a suitable device for assessing a driver's cognitive load.