Human Centered Research with Eye-Tracking and Brain-Computer Interface Technologies

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Eye-tracking technology aims to measure the point of gaze or the movement of the eyes with eye tracking devices, often to study human behavior out of the lab. Researchers are often challenged when subjects do not respond honestly or accurately due to artificial environments or discomfort. If the research aims to study real-world behaviors, lab situations or observations can change each subject’s behavior, reducing the ecological validity of the data. With eye tracking, researchers can measure behavior in natural environments and without monitoring the subjects, which lead to more valuable results. Therefore, the Swedish company Tobii has developed the Tobii Pro Glasses 2, a wearable eye tracker with wireless real-time view function that offers hardware synchronization of eye-tracking data with physiological data. 

Tobii Pro Glasses 2 © TobiiPro.com

The main advantage is that participants can freely move in the experimental environment and are not tied to computer monitors. It is also possible to synchronize eye tracking data with EEG and other biosignals such as pulse, skin connectivity, respiration rate or heart rate. Wireless EEG and biosignal acquisition systems are becoming more important in neurophysiological research, especially when studies tend to take part in the field instead of in the lab. g.Nautilus is g.tec’s wireless EEG solution that is designed to be completely different from all other devices and sets a new standard of usability. The tiny and lightweight device is attached to the EEG cap to avoid cable movements and allow completely free movement.

Tobii Pro Glasses 2 with a g.Nautilus 32 channel active electrodes

Wireless devices open up many new application and research fields. Whether you study Marketing, Web Development, Sports, Driving, etc., you are able to use Tobii Pro Glasses 2 together with Brain-Computer Interface Technology. Here is a short overview of the possibilities of eye-tracking research with Tobii Pro Glasses 2 and g.Nautilus wireless EEG.

Virtual Reality

Eye-trackers can be integrated in Virtual Reality (VR) headsets, which allow researchers to develop virtual environments. For example, VR can be used to improve how coaches, trainers or medical staff work with their subjects or even improve athletic performance without the risk of getting hurt. In marketing research, it is also possible to develop a virtual shop in order to explore customers’ comparing, buying and decision making processes. Numerous studies have used VR to treat anxiety, PTSD, phobia, and other conditions.

Eye-trackers in VR headsets can also show whether the subject is engaged to the experiment, because the level of involvement is crucial for studies. A BCI system in VR allows the user to navigate or control the scenario without any movement, and can also provide information about the user’s engagement.

Oculus Rift VR system with a flexible 64 channel g.Nautilus

Marketing Research

Eye-tracking is a very common method in marketing research, providing insights into the decision-making and buying processes, including which products people evaluate and which ones they choose. Eye-trackers can catch each consumer’s attention and spontaneous reactions to marketing actions. The results may influence product design and advertising. g.Nautilus wireless EEG system also works nicely together with eye-trackers and video cameras so that electrophysiological parameters can be analyzed for neuromarketing applications.

Market and customer research with Tobii Pro Glasses 2 © TobiiPro.com

Web Development

In the field of Interface and Web Development, it is hard to learn how different target groups deal with interactive and digital interfaces. Eye-trackers can help to test and understand the usability in mobile websites, apps, games or advertisements. These results can trigger adjustments on the specific interface in order to optimize the user experience. Using g.Nautilus wireless EEG in addition to eye-tracking, it is possible to measure what brain areas respond to interactive and digital interfaces.

Tobii Pro Glasses 2 and g.Nautilus with 32 active g.LADYbird electrodes and the flexible g.SCARABEO electrodes versions

Sports Research

When it comes to sports research, human performance is recorded with eye-trackers to learn about cognitive strategies and the link between physical tasks and visual behavior. If you want to measure EEG in addition, a lightweight device is crucial. A combination of Tobii Pro Glass 2 and g.Nautilus wireless EEG is a great platform to study how individual subjects process cognitive information and perform tasks in real world environments.

Human Performance with Tobii Pro Glasses 2 © TobiiPro.com

Driving Test Field

Eye-tracking can also be used to capture how drivers or operators of other vehicles gather information and solve tasks. By helping to evaluate cognitive workload, eye-tracking research lead to new ideas for product design, such as control panels of vehicles, to improve behavior in traffic and to reduce accidents. Real-time feedback can also warn drivers if they are becoming drowsy. g.Nautilus can also be used easily in driving test environments because of the fast montage setup and the artifact-free data, even in moving objects. Therefore, the system can easily be used in cars, plains, flight simulators and even gravity simulators for pilots and astronauts.

Tobii Pro Glasses 2 with a 64 channel g.Nautilus when driving a car

In order to use Tobii Pro Glasses 2 in combination with the wireless g.Nautilus, g.tec developed a special component: The g.EYEtracking Interface for Simulink.

How to use g.EYEtracking Interface for Simulink with Tobii Pro Glasses 2

The g.EYEtracking Interface for g.HIsys allows users to acquire biosignal data such as EEG, ECG, EMG, eye-tracking information, and other signals in real-time. It provides a block to read gaze data from the eye-tracker simultaneously with other biosignal data coming from g.USBamp, g.HIamp or g.Nautilus wireless EEG system with dry or wet electrodes.

The g.EYEtracking Interface for Simulink can acquire different eye tracking related features:

  • Pupil center in x-/y-/z-coordinated of both eyes
  • Pupil diameter of both eyes
  • Gaze direction of both eyes
  • Gaze position in relation to live scene video
  • Gaze position 3D
  • Gyroscope data
  • Accelerometer data

The following Simulink model shows the g.Nautilus and Tobii PRO Glasses 2 Interface blocks. These blocks are reading the data into the Simulink model with the same data rate.

Simulink model to process eye-tracking and EEG data in real-time

If, for example, the g.Nautilus biosignal amplifier is sampling EEG data at 250 Hz, then the eye-tracking information is aligned with the EEG data at the same sample rate. This allows users to analyze the eye-tracking and the biosignal data in real-time.

  • The Nautilus block acquires biosignal data from 1–64 channels at a sample rate of 250 or 500 Hz. Optionally, filters can be applied to the biosignal data for noise reduction.
  • The Tobii Pro Glasses 2 Interface block acquires data from the eye-tracker. The pupil’s center, diameter and gaze direction, position as well as the 3D position of the left and right eye are visualized in displays.

The gaze position is aligned with the biosignal data coming from the g.Nautilus block, visualized in the g.SCOPE block, and stored on the hard drive for offline analysis of synchronized biosignal and eye-gaze data.

Results

In this experiment, the participant was instructed to follow an object on the screen. In the rest condition of the experiment, the object was located in the center of the screen. During each task, the object moved to one of the screen corners. During offline analysis, the EEG and eye-gaze data can be triggered using the task indicator, and further processing (evoked potentials, eye-gaze velocity,…) can be applied to the data.

The following g.SCOPE screenshot shows 8 EEG channels, a task indicator and x-/y- positions of the gaze (combination of left and right eye) of the participant.

EEG and eye-gaze data visualized in g.SCOPE

The g.EYEtracking Interface for Simulink for Tobii Pro Glasses 2 is easy to use. With a little knowledge in MATLAB Simulink, you can start visualizing and processing synchronized biosignal and eye-tracker data. Using the capabilities of Simulink, it is easy to implement your signal processing algorithms for real time processing or analyze the data offline.

 

Read more:

How High-Altitude Affects Cognitive Functions
g.Nautilus for Android

g.EYEtracking Interface for EyeLink 1000 Plus

The Unlimited Possibilities of Wireless EEG
Tobii Pro Glasses 2

www.gtec.at

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