Name: assessing binocular central visual field and binocular eye movements in a dichoptic viewing condition
Uploaded: 2020-07-21T13:00:00
Description: Watch this Scientific Journal Video about Assessing Binocular Central Visual Field and Binocular Eye Movements in a Dichoptic Viewing Condition at JoVE.com

This research was funded by LC Industries Postdoctoral research fellowship to RR and Bosma Enterprises Postdoctoral research fellowship to AK. The authors would like to thank Drs. Laura Walker and Donald Fletcher for their valuable suggestions and help in subject recruitment.

All the procedures and protocol described below were reviewed and approved by the institutional review board of Wichita State University, Wichita, Kansas. Informed consent was obtained from all the participants.
1. Participant selection
<ol>
	<li>Recruited participants with normal vision (n=5, 4 females, mean &#177; SE: 39.8 &#177; 2.6 years), and with central vision loss (n=15, 11 females, 78.3 &#177; 2.3 years) due to macular degeneration (age-related/juvenile). Note that grossly different...

<ol>
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W., Naber, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Eye+tracking+under+dichoptic+viewing+conditions:+a+practical+solution.">Eye tracking under dichoptic viewing conditions: a practical solution.</a> Behavior Research Methods. 49 (4), 1303-1309 (2017).</li><li>Qian, C. S., Brascamp, J. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=How+to+build+a+dichoptic+presentation+system+that+includes+an+eye+tracker.">How to build a dichoptic presentation system that includes an eye tracker.</a> Journal of Visualized Experiments. (127), (2017).</li><li>Raveendran, R. N., Bobier, W. R., Thompson, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Binocular+vision+and+fixational+eye+movements.">Binocular vision and fixational eye movements.</a> Journal of Vision. 19 (4), 1-15 (2019).</li><li>. Binocular vision and fixational eye movements Available from: <a target="_blank" href="https://uwspace.uwaterloo.ca/handle/10112/12076">https://uwspace.uwaterloo.ca/handle/10112/12076</a> (2017)</li><li>. Fixational eye movements in strabismic amblyopia Available from: <a target="_blank" href="https://uwspace.uwaterloo.ca/handle/10012/7478">https://uwspace.uwaterloo.ca/handle/10012/7478</a> (2013)</li><li>Maiello, G., Chessa, M., Solari, F., Bex, P. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Simulated+disparity+and+peripheral+blur+interact+during+binocular+fusion.">Simulated disparity and peripheral blur interact during binocular fusion.</a> Journal of Vision. 14 (8), (2014).</li><li>Maiello, G., Harrison, W. J., Bex, P. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Monocular+and+binocular+contributions+to+oculomotor+plasticity.">Monocular and binocular contributions to oculomotor plasticity.</a> Scientific Reports. 6, (2016).</li><li>Maiello, G., Kwon, M. Y., Bex, P. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Three-dimensional+binocular+eye-hand+coordination+in+normal+vision+and+with+simulated+visual+impairment.">Three-dimensional binocular eye-hand coordination in normal vision and with simulated visual impairment.</a> Experimental Brain Research. 236 (3), 691-709 (2018).</li><li>Agaoglu, S., Agaoglu, M. N., Das, V. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Motion+Information+via+the+Nonfixating+Eye+Can+Drive+Optokinetic+Nystagmus+in+Strabismus.">Motion Information via the Nonfixating Eye Can Drive Optokinetic Nystagmus in Strabismus.</a> Investigative Opthalmology &amp; Visual Science. 56 (11), 6423 (2015).</li><li>Erkelens, C. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fusional+limits+for+a+large+random-dot+stereogram.">Fusional limits for a large random-dot stereogram.</a> Vision Research. 28 (2), 345-353 (1988).</li><li>Seiple, W., Szlyk, J. P., McMahon, T., Pulido, J., Fishman, G. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Eye-movement+training+for+reading+in+patients+with+age-related+macular+degeneration.">Eye-movement training for reading in patients with age-related macular degeneration.</a> Investigative Ophthalmology and Visual Science. 46 (8), 2886-2896 (2005).</li><li>Aguilar, C., Castet, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gaze-contingent+simulation+of+retinopathy:+Some+potential+pitfalls+and+remedies.">Gaze-contingent simulation of retinopathy: Some potential pitfalls and remedies.</a> Vision Research. 51 (9), 997-1012 (2011).</li><li>Pratt, J. D., Stevenson, S. B., Bedell, H. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Scotoma+Visibility+and+Reading+Rate+with+Bilateral+Central+Scotomas.">Scotoma Visibility and Reading Rate with Bilateral Central Scotomas.</a> Optom Vis Sci. 94 (31), 279-289 (2017).</li><li>Babu, R. J., Clavagnier, S., Bobier, W. R., Thompson, B., Hess, R. F., PGH, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Regional+Extent+of+Peripheral+Suppression+in+Amblyopia.">Regional Extent of Peripheral Suppression in Amblyopia.</a> Investigative Opthalmology &amp; Visual Science. 58 (4), 2329 (2017).</li><li>Ebenholtz, S. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Motion+Sickness+and+Oculomotor+Systems+in+Virtual+Environments.">Motion Sickness and Oculomotor Systems in Virtual Environments.</a> Presence: Teleoperators and Virtual Environments. 1 (3), 302-305 (1992).</li></ol>

The proposed method of measuring eye movements in dichoptic viewing condition has many potential applications. Assessing binocular visual fields in participants with central vision loss that is demonstrated here is one such application. We used this method to assess binocular visual field in fifteen participants with central vision loss to study how binocular viewing influences the heterogeneous central visual field loss.
The most important step in the protocol is positioning (distance from ey...

Macular degeneration is generally a bilateral condition affecting central vision and the pattern of visual loss can be heterogeneous. The central visual loss could be either symmetrical or asymmetrical between two eyes1. Currently, there are several techniques available to assess the central visual field in macular degeneration. The Amsler grid chart contains a grid pattern that can be used to manually screen central visual field. Automated perimeters (e.g., Humphrey visual field analyzer) present light flashes of varying brightness and sizes in a standardized ganzfeld bowl to probe the visual field. Gaze-contingent microperimetry presents visual stimulus on an LCD display. Micro-perimeters can compensate micro-eye movements by tracking a region of interest on the retina. Micro-perimeters can probe local regions in the central retina for changes in function but can test only one eye at a time. Consequently, micro-perimetric testing cannot explain how the heterogeneous defects in each eye affect the binocular interaction and real-world function. There is an unmet need for a method to reliably assess visual fields in a viewing condition that closely approximates real-world viewing. Such an assessment is necessary to understand how the visual field defect of one eye affects/contributes to the binocular visual field defect. We propose a novel method for assessing central visual field in people with central visual loss under dichoptic viewing condition (i.e., when visual stimuli are independently presented to each of the two eyes).
To measure visual fields reliably, fixation must be maintained at a given locus. Therefore, it is important to combine the eye-tracking and dichoptic presentation for binocular assessment. However, combining these two techniques can be challenging due to interference between the illuminating systems of the eye-tracker (e.g., infrared LEDs) and the optical elements of the dichoptic presenting systems (e.g., mirrors of haploscope or prisms of stereoscopes). Alternative options are to use an eye-tracking technique that does not interfere with the line of sight (e.g., scleral coil technique) or an eye-tracker that is integrated with goggles2. Though each method has its own benefits, there are disadvantages. The former method is considered invasive and can cause considerable discomfort3 and the latter methods have low temporal resolutions (60 Hz)4. To overcome these issues, Brascamp &#38; Naber (2017)5 and Qian &#38; Brascamp (2017)6 used a pair of cold mirrors (which transmitted infrared light but reflected 95% of the visible light) and a pair of monitors on either side of the cold mirrors to create a dichoptic presentation. Infrared video-based eye-tracker was used to track eye movements in the haploscope setup7,8.
However, using a haploscope-type dichoptic presentation has a drawback. The center of rotation of the instrument (haploscope) is different from the center of rotation of the eye. Therefore, additional calculations (as described in Appendix &#8211; A of Raveendran (2013)9) are required for proper and accurate measurements of eye movements. In addition, the planes of accommodation and vergence must be aligned (i.e., demand for accommodation and vergence must be the same). For example, if the working distance (total optical distance) is 40 cm, then the demand for accommodation and vergence is 2.5 diopters and 2.5-meter angles, respectively. If we align the mirrors perfectly orthogonal, then the haploscope is aligned for distant viewing (i.e., required vergence is zero), but the required accommodation is still 2.5D. Therefore, a pair of convex lenses (+2.50 diopters) must be placed between the eye and mirror arrangement of haploscope to push the plane of accommodation to infinity (i.e., required accommodation is zero). This arrangement necessitates more space between the eye and mirror arrangement of haploscope is required, which takes us back to the difference in centers of rotation. The issue of aligning planes of accommodation and vergence can be minimized by aligning the haploscope to the near viewing such that both the planes are aligned. However, this requires measurement of inter-pupillary distance for every participant and the corresponding alignment of haploscope mirrors/stimulus presenting monitors.
In this paper, we introduce a method to combine infrared video-based eye-tracking and dichoptic stimulus presentation using wireless 3D shutter glasses and 3D-ready monitors. This method does not require any additional calculations and/or assumptions like those used with the haploscopic method. Shutter glasses have been used in conjunction with eye trackers for understanding binocular fusion10, saccadic adaptation11, and eye-hand coordination12. However, it should be noted that stereo-shutter glasses used by Maiello and colleagues10,11,12 were the first-generation shutter glasses, which were connected through a wire to synchronize with the monitor refresh rate. Moreover, the first-generation shutter glasses are commercially unavailable now. Here, we demonstrate the use of commercially available second-generation wireless shutter glasses (Table of Materials) to present dichoptic stimulus and reliably measure monocular and binocular eye-movements. Additionally, we demonstrate a method to assess monocular/binocular visual fields in subjects with central visual field loss. While dichoptic presentation of visual stimulus enables monocular and binocular assessment of visual fields, binocular eye tracking under dichoptic viewing condition facilitates visual fields testing in a gaze-controlled paradigm.

<table>
	<tbody>
		<tr>
			<td>3D monitor</td>
			<td>Benq</td>
			<td>NA</td>
			<td>Approximate Cost (in USD): 500 
			https://zowie.benq.com/en/product/monitor/xl/xl2720.html</td>
		</tr>
		<tr>
			<td>3D shutter glass</td>
			<td>NVIDIA</td>
			<td>NA</td>
			<td>Approximate Cost (in USD): 300 
			https://www.nvidia.com/object/product-geforce-3d-vision2-wireless-glasses-kit-us.html</td>
		</tr>
		<tr>
			<td>Chin/forehead rest</td>
			<td>UHCO</td>
			<td>NA</td>
			<td>Approximate Cost (in USD): 750 
			https://www.opt.uh.edu/research-at-uhco/uhcotech/headspot/</td>
		</tr>
		<tr>
			<td>Eyetracker</td>
			<td>SR Research</td>
			<td>NA</td>
			<td>Approximate Cost (in USD): 27,000 
			https://www.sr-research.com/eyelink-1000-plus/</td>
		</tr>
		<tr>
			<td>IR reflective patch</td>
			<td>Tactical</td>
			<td>NA</td>
			<td>Approximate Cost (in USD): 10 
			https://www.empiretactical.org/infrared-reflective-patches/tactical-infrared-ir-square-patch-with-velcro-hook-fastener-1-inch-x-1-inch</td>
		</tr>
		<tr>
			<td>MATLAB Software</td>
			<td>Mathworks</td>
			<td>NA</td>
			<td>Approximate Cost (in USD): 2150 
			https://www.mathworks.com/pricing-licensing.html</td>
		</tr>
		<tr>
			<td>Numerical Keypad</td>
			<td>Amazon</td>
			<td>CP001878 (model), B01E8TTWZ2 (ASIN)</td>
			<td>Approximate Cost (in USD): 15 
			https://www.amazon.com/Numeric-Jelly-Comb-Portable-Computer/dp/B01E8TTWZ2</td>
		</tr>
		<tr>
			<td>Psychtoolbox - Add on</td>
			<td>Freeware</td>
			<td>NA</td>
			<td>Approximate Cost (in USD): FREE 
			http://psychtoolbox.org/download.html</td>
		</tr>
		<tr>
			<td>Tripod (Dekstop)</td>
			<td>Manfrotto</td>
			<td>MTPIXI-B (model), B00D76RNLS (ASIN)</td>
			<td>Approximate Cost (in USD): 30 
			https://www.amazon.com/dp/B00D76RNLS</td>
		</tr>
	</tbody>
</table>

assessing binocular central visual field and binocular eye movements in a dichoptic viewing condition

Macular degeneration typically results in heterogeneous binocular central visual defects. Currently available approaches to assess central visual field, like the microperimetry, can test only one eye at a time. Therefore, they cannot explain how the defects in each eye affect the binocular interaction and real-world function. Dichoptic stimulus presentation with a gaze-controlled system could provide a reliable measure of monocular/binocular visual fields. However, dichoptic stimulus presentation and simultaneous eye-tracking are challenging because optical devices of instruments that present stimulus dichoptically (e.g., haploscope) always interfere with eye-trackers (e.g., infrared video-based eye-trackers). Therefore, the goals were 1) to develop a method for dichoptic stimulus presentation with simultaneous eye-tracking, using 3D-shutter glasses and 3D-ready monitors, that is not affected by interference and 2) to use this method to develop a protocol for assessing central visual field in subjects with central vision loss. The results showed that this setup provides a practical solution for reliably measuring eye-movements in dichoptic viewing condition. In addition, it was also demonstrated that this method can assess gaze-controlled binocular central visual field in subjects with central vision loss.

The representative binocular eye-movement traces of one observer with normal binocular vision during two different viewing conditions is shown (Figure 4). Continuous tracking of eye movements was possible when both eyes viewed the stimulus (Figure 4A), and when the left eye viewed the stimulus with the right eye under an active shutter (Figure 4B). As evident from these traces, the proposed method does not impact the quality of eye-...

Watch this Scientific Journal Video about Assessing Binocular Central Visual Field and Binocular Eye Movements in a Dichoptic Viewing Condition at JoVE.com

Assessing Binocular Central Visual Field and Binocular Eye Movements in a Dichoptic Viewing Condition

Presented here is a protocol for assessing binocular eye movements and gaze-controlled central visual field screening in participants with central vision loss.

Macular degeneration typically results in heterogeneous binocular central visual defects. Currently available approaches to assess central visual field, ...

Currently available methods for assessing central visual field are monocular. We use dichoptic stimuli presentation with the gaze control system for a reliable monocular and binocular visual field assessment. This method utilizes 3D-ready monitor and 3D shutter glasses for dichoptic stimuli presentation which provides simpler and more straightforward approaches than other methods, example using a haploscope.Demonstrating the procedure of testing will be Dr.Guler Arsal, a postdoctoral research associate at the Envision Research Institute. Before beginning an experiment, select a pair of wireless 3D active shutter glasses that can be synced with any 3D-ready monitor. For the shutter glasses to be active, there should be no interference between the infrared transmitter and the infrared receiver on the nose bridge of the shutter glasses.Display all of the visual stimuli on a 3D monitor at a 1920 by 1080 pixels, 144 Hertz resolution. For the monitor and the 3D glasses to work seamlessly, ensure that the appropriate drivers are installed. Place a table-mounted infrared video-based eye tracker that is capable of measuring eye movements at a 1, 000 Hertz sampling rate on the table next to the monitor and place a seat for the participant 100 centimeters from the monitor.Use a tripod to set up the eye tracker camera 20 to 30 centimeters from where the participant will be seated and use an infrared reflective patch to avoid interference between the infrared illumination of the eye tracker and the infrared system of the shutter glasses. Use commercially available software to integrate the shutter glasses with the 3D-ready monitor for the dichoptic presentation of visual stimuli to control the eye tracker. Clamp a tall wide chin and forehead rest to an adjustable table to allow comfortable positioning of the participant once the shutter glasses are on.Place the infrared reflective patch below the sensor and deactivate the light boost option in the 3D-ready monitor to minimize any leakage of the luminance information, then increase the strength of the infrared LEDs of the eye tracker to 100%from the default 50%in the software. A few minutes before the participant arrives, check that the eye tracker and host computer are on and confirm that the computer is connected to the eye tracker. Then check the synchronization accuracy of the display.When the participant arrives, have them sit with their head and chin in the rest and ask them to put on the 3D active shutter glasses. When the participant is comfortable, initiate the program that runs the main experiment from the appropriate interface. When prompted by the program, enter the participant information and save the output data file in a data folder with a unique filename.When a gray screen with instructions such as press Enter to toggle camera, press C to calibrate, press V to validate appears on the screen, adjust the camera of the eye tracker to align with the participant's pupil. For eye tracker calibration, initiate the calibration in the software and instruct the participant to follow the target by moving their eyes, but not their head, and to look at the center of the target. If the calibration is successful, initiate the validation and instruct the participant to once again follow the target with their eyes only while looking at the center of the target.Then read the results of the validation step on the screen. Once a good fair calibration and validation of the eye tracker has been achieved, initiate the drift correction and instruct the participant to look at the central fixation target while holding their eyes as steady as possible. Upon completion of the drift correction, inform the participant that they need to keep both eyes open during the entire testing, to hold the fixation at the central fixation target, and to press Enter in response to any white light observed.Instruct the participant not to search for new white lights and to not move their eyes and that the lights can appear at any location on the screen. At the end of the visual field experiment, the screen will display the result of the testing, differentially highlighting the seen and not seen locations. Although all of the visual field and eye movement data will be saved automatically for post-hoc analysis, be sure to confirm that the files have been saved before quitting the platform running the experiment.Here, the representative binocular eye movement traces of one observer with normal binocular vision during two different viewing conditions are shown. Continuous tracking of eye movements is possible when both eyes view the stimulus and when the left eye views the stimulus with the right eye under an active shutter. As evident, this method does not impact the quality of eye movement measurement and can measure eye movements for even long duration experiments.As observed, the method can be used to reliably measure eye movements even in challenging participants with central vision loss. Indeed, an important application of this method is screening the central visual field in subjects with and without central vision loss. The method provides a way to document the impact of central vision loss in a real world viewing with both eyes open as for this representative observer in which binocular advantage was observed.A successful synchronization of 3D-ready monitor and the 3D shutter glasses with the eye tracker can be achieved by strategically placing the infrared reflective patch. Although we demonstrated as a single visual field only, this method can be expanded to measure the threshold at each retinal location to study the monocular and binocular visual field deficits.

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Research

JoVE Journal

Behavior

Using Eye Movements to Evaluate the Cognitive Processes Involved in Text Comprehension

The present article describes how to use eye tracking methodologies to study the cognitive processes involved in text comprehension. Measuring eye movements during reading is one of the most precise methods for measuring moment-by-moment (online) processing demands during text comprehension. Cognitive processing demands are reflected by several aspects of eye movement behavior, such as fixation duration, number of fixations, and number of regressions (returning to prior parts of a text). Important properties of eye tracking equipment that researchers need to consider are described, including how frequently the eye position is measured (sampling rate), accuracy of determining eye position, how much head movement is allowed, and ease of use. Also described are properties of stimuli that influence eye movements that need to be controlled in studies of text comprehension, such as the position, frequency, and length of target words. Procedural recommendations related to preparing the participant, setting up and calibrating the equipment, and running a study are given. Representative results are presented to illustrate how data can be evaluated. Although the methodology is described in terms of reading comprehension, much of the information presented can be applied to any study in which participants read verbal stimuli.

The present article describes how to use eye tracking methodologies to study the cognitive processes involved in text comprehension. Descriptions of eye tracking equipment, how to develop experimental stimuli, and procedural recommendations are included. The information presented can be applied to most any study using verbal stimuli.

The present article describes how to use eye  tracking methodologies to study the cognitive processes involved in text  comprehension. Measuring eye ...

A Method to Quantify Visual Information Processing in Children Using Eye Tracking

Visual problems that occur early in life can have major impact on a child's development. Without verbal communication and only based on observational methods, it is difficult to make a quantitative assessment of a child's visual problems. This limits accurate diagnostics in children under the age of 4 years and in children with intellectual disabilities. Here we describe a quantitative method that overcomes these problems. The method uses a remote eye tracker and a four choice preferential looking paradigm to measure eye movement responses to different visual stimuli. The child sits without head support in front of a monitor with integrated infrared cameras. In one of four monitor quadrants a visual stimulus is presented. Each stimulus has a specific visual modality with respect to the background, e.g., form, motion, contrast or color. From the reflexive eye movement responses to these specific visual modalities, output parameters such as reaction times, fixation accuracy and fixation duration are calculated to quantify a child's viewing behavior. With this approach, the quality of visual information processing can be assessed without the use of communication. By comparing results with reference values obtained in typically developing children from 0-12 years, the method provides a characterization of visual information processing in visually impaired children. The quantitative information provided by this method can be advantageous for the field of clinical visual assessment and rehabilitation in multiple ways. The parameter values provide a good basis to: (i) characterize early visual capacities and consequently to enable early interventions; (ii) compare risk groups and follow visual development over time; and (iii), construct an individual visual profile for each child.

A method is described to quantify the quality of visual information processing based on reflexive eye movements in response to specific visual modalities. Reaction times and fixation output parameters are used to characterize visual performance in children with and without visual impairments from 6 months of age.

Visual problems that occur early in life can have major impact on a child's development. Without verbal communication and only based on observational ...

How to Build a Dichoptic Presentation System That Includes an Eye Tracker

The presentation of different stimuli to the two eyes, dichoptic presentation, is essential for studies involving 3D vision and interocular suppression. There is a growing literature on the unique experimental value of pupillary and oculomotor measures, especially for research on interocular suppression. Although obtaining eye-tracking measures would thus benefit studies that use dichoptic presentation, the hardware essential for dichoptic presentation (e.g. mirrors) often interferes with high-quality eye tracking, especially when using a video-based eye tracker. We recently described an experimental setup that combines a standard dichoptic presentation system with an infrared eye tracker by using infrared-transparent mirrors1. The setup is compatible with standard monitors and eye trackers, easy to implement, and affordable (on the order of US$1,000). Relative to existing methods it has the benefits of not requiring special equipment and posing few limits on the nature and quality of the visual stimulus. Here we provide a visual guide to the construction and use of our setup.

We recently proposed a method that allows dichoptic visual stimulus presentation and binocular eye tracking simultaneously1. The key is the combination of an infrared eye tracker and the corresponding infrared-transparent mirrors. This manuscript provides an in depth protocol for initial setup and everyday operation.

The presentation of different stimuli to the two eyes, dichoptic presentation, is essential for studies involving 3D vision and interocular suppression. ...

Central and Divided Visual Field Presentation of Emotional Images to Measure Hemispheric Differences in Motivated Attention

Two dominant theories on lateralized processing of emotional information exist in the literature. One theory posits that unpleasant emotions are processed by right frontal regions, while pleasant emotions are processed by left frontal regions. The other theory posits that the right hemisphere is more specialized for the processing of emotional information overall, particularly in posterior regions.
Assessing the different roles of the cerebral hemispheres in processing emotional information can be difficult without the use of neuroimaging methodologies, which are not accessible or affordable to all scientists. Divided visual field presentation of stimuli can allow for the investigation of lateralized processing of information without the use of neuroimaging technology. 
This study compared central versus divided visual field presentations of emotional images to assess differences in motivated attention between the two hemispheres. The late positive potential (LPP) was recorded using electroencephalography (EEG) and event-related potentials (ERPs) methodologies to assess motivated attention. Future work will pair this paradigm with a more active behavioral task to explore the behavioral impacts on the attentional differences found.

This study compared central versus divided visual field presentations of emotional images to assess differences in motivated attention between the two hemispheres. The late positive potential (LPP) was recorded using electroencephalography (EEG) and event-related potentials (ERPs) methodologies to assess motivated attention.

Two dominant theories on lateralized processing of emotional information exist in the literature. One theory posits that unpleasant emotions are processed ...

Eye Tracking During Visually Situated Language Comprehension: Flexibility and Limitations in Uncovering Visual Context Effects

The present work is a description and an assessment of a methodology designed to quantify different aspects of the interaction between language processing and the perception of the visual world. The recording of eye-gaze patterns has provided good evidence for the contribution of both the visual context and linguistic/world knowledge to language comprehension. Initial research assessed object-context effects to test&#160;theories of modularity in language processing. In the introduction, we describe how subsequent investigations have taken the role of the wider visual context in language processing as a research topic in its own right, asking questions such as how our visual perception of events and of speakers contributes to&#160;comprehension informed by&#160;comprehenders&#39; experience. Among the examined aspects of the visual context are actions, events, a speaker&#39;s gaze, and emotional facial expressions, as well as spatial object configurations. Following an overview of the eye-tracking method and its different applications, we list the key steps of the methodology in the protocol, illustrating how to successfully use it to study visually-situated language comprehension. A final section presents three sets of representative results and illustrates the benefits and limitations of eye tracking for investigating the interplay between the perception of the visual world and language comprehension.

The present article reviews an eye-tracking methodology for studies on language comprehension. To obtain reliable data, key steps of the protocol must be followed. Among these are the correct set-up of the eye tracker (e.g., ensuring good quality of the eye and head images) and accurate calibration.

The present work is a description and an assessment of a methodology designed to quantify different aspects of the interaction between language processing ...

Using Eye Movements Recorded in the Visual World Paradigm to Explore the Online Processing of Spoken Language

In a typical eye tracking study using the visual world paradigm, participants' eye movements to objects or pictures in the visual workspace are recorded via an eye tracker as the participant produces or comprehends a spoken language describing the concurrent visual world. This paradigm has high versatility, as it can be used in a wide range of populations, including those who cannot read and/or who cannot overtly give their behavioral responses, such as preliterate children, elderly adults, and patients. More importantly, the paradigm is extremely sensitive to fine grained manipulations of the speech signal, and it can be used to study the online processing of most topics in language comprehension at multiple levels, such as the fine grained acoustic phonetic features, the properties of words, and the linguistic structures. The protocol described in this article illustrates how a typical visual world eye tracking study is conducted, with an example showing how the online processing of some semantically complex statements can be explored with the visual world paradigm.

The visual world paradigm monitors participants' eye movements in the visual workspace as they are listening to or speaking a spoken language. This paradigm can be used to investigate the online processing of a wide range of psycholinguistic questions, including semantically complex statements, such as disjunctive statements.

In a typical eye tracking study using the visual world paradigm, participants' eye movements to objects or pictures in the visual workspace are recorded ...

Eye-tracking to Distinguish Comprehension-based and Oculomotor-based Regressive Eye Movements During Reading

Regressive eye movements are eye movements that move backwards through the text and comprise approximately 10-25% of eye movements during reading. As such, understanding the causes and mechanisms of regressions plays an important role in understanding eye movement behavior. Inhibition of return (IOR) is an oculomotor effect that results in increased latency to return attention to a previously attended target versus a target that was not previously attended. Thus, IOR may affect regressions. This paper describes how to design materials to distinguish between regressions caused by comprehension-related and oculomotor processes; the latter is subject to IOR. The method allows researchers to identify IOR and control the causes of regressions. While the method requires tightly controlled materials and large numbers of participants and materials, it allows researchers to distinguish and control the types of regressions that occur in their reading studies.

The method was designed to investigate the role of inhibition of return (IOR) in regressive eye movements during reading. The focus is on differentiating between regressions triggered as a result of comprehension difficulty versus those triggered from oculomotor error, including the role of IOR in the two types of regressions.

Regressive eye movements are eye movements that move backwards through the text and comprise approximately 10-25% of eye movements during reading. As ...

Investigating the Deployment of Visual Attention Before Accurate and Averaging Saccades via Eye Tracking and Assessment of Visual Sensitivity

This experimental protocol was designed to investigate whether visual attention is obligatorily deployed at the endpoint of saccades. To this end, we recorded the eye position of human participants engaged in a saccade task via eye tracking and assessed visual orientation discrimination performance at various locations during saccade preparation. Importantly, instead of using a single saccade target paradigm for which the saccade endpoint typically coincides roughly with the target, this protocol comprised the presentation of two nearby saccade targets, leading to a distinct spatial dissociation between target locations and saccade endpoint on a substantial number of trials. The paradigm allowed us to compare presaccadic visual discrimination performance at the endpoint of accurate saccades (landing at one of the saccade targets) and of averaging saccades (landing at an intermediate location in between the two targets). We observed a selective enhancement of visual sensitivity at the endpoint of accurate saccades but not at the endpoint of averaging saccades. Rather, before the execution of averaging saccades, visual sensitivity was equally enhanced at both targets, suggesting that saccade averaging follows from unresolved attentional selection among the saccade targets. These results argue against a mandatory coupling between visual attention and saccade programming based on a direct measure of presaccadic visual sensitivity rather than saccadic reaction times, which have been used in other protocols to draw similar conclusions. While our protocol provides a useful framework to investigate the relationship between visual attention and saccadic eye movements at the behavioral level, it can also be combined with electrophysiological measures to extend insights at the neuronal level.

This experimental protocol combined eye tracking and the assessment of presaccadic visual sensitivity in a dual task paradigm, consisting of a free choice saccade task and a visual discrimination task, to investigate the deployment of visual spatial attention before both, accurate and averaging saccades.

This experimental protocol was designed to investigate whether visual attention is obligatorily deployed at the endpoint of saccades. To this end, we ...

Multimodal Protocol for Assessing Metacognition and Self-Regulation in Adults with Learning Difficulties

Learning disabilities (LDs) encompass disorders of those who have difficulty learning and using academic skills, exhibiting performance below expectations for their chronological age in the areas of reading, writing, and/or mathematics. Each of the disorders making up the LDs involve different deficits; however, some commonalities can be found within that heterogeneity, such in terms of learning self-regulation and metacognition. Unlike in early ages and later educational levels, there are hardly any evidence-based evaluation protocols for adults with LDs. LDs influence academic performance but also have serious consequences in professional, social, and family contexts. In response to this, the current work proposes a multimodal evaluation protocol focused on metacognitive, self-regulation of learning, and emotional processes, which make up the basis of the difficulties in adults with LDs. The assessment is carried out through analysis of the on-line learning process using a variety methods, techniques, and sensors (e.g., eye tracking, facial expressions of emotion, physiological responses, concurrent verbalizations, log files, screen recordings of human-machine interactions) and off-line methods (e.g., questionnaires, interviews, and self-report measures). This theoretically-driven and empirically-based guideline aims to provide an accurate assessment of LDs in adulthood in order to design effective prevention and intervention proposals.

The current work proposes a multimodal evaluation protocol focused on metacognitive, self-regulation of learning, and emotional processes, which make up the basis of the difficulties in adults with LDs.

Learning disabilities (LDs) encompass disorders of those who have difficulty learning and using academic skills, exhibiting performance below expectations ...

A Methodology for Capturing Joint Visual Attention Using Mobile Eye-Trackers

With the advent of new technological advances, it is possible to study social interactions at a microlevel with unprecedented accuracy. High frequency sensors, such as eye-trackers, electrodermal activity wristbands, EEG bands, and motion sensors provide observations at the millisecond level. This level of precision allows researchers to collect large datasets on social interactions. In this paper, I discuss how multiple eye-trackers can capture a fundamental construct in social interactions, joint visual attention (JVA). JVA has been studied by developmental psychologists to understand how children acquire language, learning scientists to understand how small groups of learners work together, and social scientists to understand interactions in small teams. This paper describes a methodology for capturing JVA in colocated settings using mobile eye-trackers. It presents some empirical results and discusses implications of capturing microobservations to understand social interactions.

Using multimodal sensors is a promising way to understand the role of social interactions in educational settings. This paper describes a methodology for capturing joint visual attention from colocated dyads using mobile eye-trackers.

With the advent of new technological advances, it is possible to study social interactions at a microlevel with unprecedented accuracy. High frequency ...