The authors thank Pieter Schiphorst for his role in designing the setup and for providing the graphics of Figures 1 and 3, and Marnix Naber for helpful discussion and his contribution to Figure 6. The authors also acknowledge researchers and publishers for reusing Figure 1 and 6 from a published paper1.

This protocol has been approved by the Institutional Review Boards of Michigan State University.
1. Building the system
<ol>
	<li>Rationale
	<ol>
		<li>Prepare the mirror setup, a variant of the classic Wheatstone stereoscope28 illustrated in Figure 1, consisting of two mirrors positioned at a 45&#176; angle relative to the participant&#39;s midline. The mirrors reflect stimuli from two screens that are positioned at opposite ends of a table, facing each other.</li>
		<li>Seat a participant in front of the mirrors and have them view a different screen, reflected via a different mirror, with each eye. For best results, use a head rest for stabilizing the participant&#39;s head.</li>
		<li>Position an infrared-sensitive video-based eye tracker, including a camera and an illuminator, in front of the participant but behind the mirrors. The eye tracker is represented by a box in Figure 1. 
		NOTE: One challenge when trying to track the eyes in normal setups of this type, is that the eyes are blocked by the mirrors.</li>
		<li>Use two front-surface mirrors, often advertised as &#34;cold mirrors&#34; (incident angle: 45&#176;), that feature near-complete reflectance of visible wavelengths and near-complete transmission of near-infrared wavelengths (see Table 1 for detailed information about the mirrors). 
		NOTE: Such mirrors can be obtained via companies supplying optical equipment for scientific and industrial purposes, which usually list components like these as &#39;cold mirrors&#39; or as a type of &#39;dichroic mirrors&#39; (see more detail in Materials/Equipment Table).
		<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
			<tbody>
				<tr>
					<td colspan="2"></td>
					<td>Setup 1</td>
					<td>Setup 2</td>
				</tr>
				<tr>
					<td rowspan="3">Mirrors</td>
					<td>Dimensions</td>
					<td>10.10 &#215; 12.70 cm</td>
					<td>10.10 &#215; 12.70 cm</td>
				</tr>
				<tr>
					<td>Reflectance</td>
					<td>400 ~ 690 nm</td>
					<td>425 ~ 650 nm</td>
				</tr>
				<tr>
					<td>Transmission</td>
					<td>750 ~ 1200 nm</td>
					<td>800 ~ 1200 nm</td>
				</tr>
				<tr>
					<td rowspan="2">Eye Tracker</td>
					<td>Brand</td>
					<td>Research-end Eye Tracker</td>
					<td>Customer-grade Eye Tracker</td>
				</tr>
				<tr>
					<td>Transmission</td>
					<td>890 ~ 940 nm</td>
					<td>Around 850 nm</td>
				</tr>
			</tbody>
		</table>
		 
		Table 1. Details of two versions of the setup with which we have worked. 
		The eye tracker&#39;s transmission wave length range is covered by the mirrors&#39; transmission range at a 45&#176; incidence angle, but outside their reflectance range.</li>
	</ol>
	</li>
	<li>Structure of the Setup
	<ol>
		<li>Build the setup on top of a desk. Besides the mirrors and eye tracker, it consists only of three custom-built elements made of fiberboard (see Figure 2 for an assembly guide) and two flat-screen monitors on monitor-arms available from normal office supply stores.</li>
		<li>Fiberboard elements
		<ol>
			<li>Build the framework of the setup from three components of fiberboards: one central component and two reference boards on each side (see Figure 1 for general positioning, Table 2 for detailed dimensions, and Figure 2 for an assembly guide of each component). Paint all these pieces in matte black to reduce light scatter. 
			NOTE: The central component (see Figure 2B and 2D) holds the mirrors and eye tracker. Both are on the same plateau, thus keeping the eye tracker at participants&#39; eye level.</li>
			<li>Place the top element of this component such that it leaves 8 cm in depth in the front of the desk. Such an arrangement allows enough room for the participant&#39;s face when stabilized on the head rest and avoids condensation on the mirrors during expiration, while minimizing the distance between the participant&#39;s eyes and the mirrors to maximize the possible use of the participant&#39;s visual field.</li>
			<li>Position the two reference boards straight below the monitors (see Figure 1 for positioning and Figure 2 panels A and C for an assembly guide) for easy manual calibration of the screens. Note that the apparent offset in Figure 1 between screen and board is due to limited depth cues in the image; the boards are straight below the monitors on both sides.</li>
			<li>Exactly align the long horizontals with the edges of the desk, while the long verticals leave 4 cm beyond the front of the desk for ease of stabilizing a calibration board (see below) to these boards. The two small verticals will ensure the long vertical staying vertical as the reference for the monitors.</li>
			<li>Optionally, use a separate piece of fiberboard as a calibration board (see Figure 3). In this case, after obtaining an optimal position of a monitor, position the calibration board against the reference board and indicate the positions of both the reference board and the monitor on the calibration board while it is in place (in the example of Figure 3, wooden slats provide these indications).</li>
			<li>Whenever this desired monitor position is lost (accidentally or because other experiments require a different position), retrieve this position by using the markings on the calibration board to put the calibration board back in the same place relative to the reference board that has a fixed position on the desk. Move the monitor again to line up with the appropriate markings (see step 2.1.1. for details).
			<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
				<tbody>
					<tr>
						<td>Component</td>
						<td>Dimensions (cm)</td>
						<td>Number</td>
						<td>Remark</td>
					</tr>
					<tr>
						<td rowspan="4">Central Component</td>
						<td>80 &#215; 25 &#215; 2</td>
						<td>1</td>
						<td>Horizontal top</td>
					</tr>
					<tr>
						<td>23 &#215; 25 &#215; 2</td>
						<td>1</td>
						<td>Horizontal bottom</td>
					</tr>
					<tr>
						<td>21 &#215; 32 &#215; 2</td>
						<td>1</td>
						<td>Central vertical</td>
					</tr>
					<tr>
						<td>32 &#215; 25 &#215; 2</td>
						<td>1</td>
						<td>Front-facing vertical</td>
					</tr>
					<tr>
						<td rowspan="3">Reference Boards</td>
						<td>61 &#215; 11 &#215; 2</td>
						<td>2</td>
						<td>Long horizontal</td>
					</tr>
					<tr>
						<td>66 &#215; 29 &#215; 2</td>
						<td>2</td>
						<td>Long vertical</td>
					</tr>
					<tr>
						<td>11 &#215; 15 &#215; 2</td>
						<td>4</td>
						<td>Small vertical</td>
					</tr>
				</tbody>
			</table>
			 
			Table 2. Details of the fiberboard components.</li>
		</ol>
		</li>
		<li>Monitors and Mirrors
		<ol>
			<li>Position the setup on top of a standard office desk.</li>
			<li>Mount two flat-screen monitors on standard monitor arms clamped to the side of the desk (clamping both the reference board and the desk). These arms allow translation in three dimensions as well as rotation in the plane of the screen. Conventional CRT-monitors are clearly also compatible with the setup, but would not afford the same flexibility in terms of positioning and repositioning.</li>
			<li>Mount the mirrors on mirror mounts that are sold for the purpose by the same suppliers that stock cold mirrors. Connect these mounts to the fiber board holding the mirror at participants&#39; eye level. Position the mirrors to touch at a 90&#176; angle in the center, right before the participant&#39;s nose.</li>
		</ol>
		</li>
		<li>Remaining elements 
		NOTE: Some experiments require participants not seeing the screens from the corner of their eyes, so that a direct line of sight to the screens (dashed lines in Figure 4A) should be avoided.
		<ol>
			<li>In that case, create &#34;blinders&#34; made of black cardboard and foam-padded hole straps painted in black, and attach them to the posts of the head rest (see Figure 4B). Adjust the blinders in height and angle to accommodate individual participants. If the wall in front of the participant has high reflectance, hanging a piece of black fabric will help remedy this.</li>
		</ol>
		</li>
	</ol>
	</li>
</ol>
2. Using the system
<ol>
	<li>Hardware calibration 
	NOTE: The purpose of calibration is to achieve satisfactory alignment of the two monitors for ease of fusion of the two monitors&#39; images for each participant. This can be achieved in two steps: hardware calibration (described here) and software calibration (described below).
	<ol>
		<li>When using a calibration board, as described above, align it with one of the reference boards, holding it in place with a C-clamp if needed, and then move the corresponding monitor to line up with the desired reference lines on the calibration board. The monitors should be parallel to each other, and each should be straight above its reference board.</li>
		<li>When using blinders, move them to the participant&#39;s eye level and rotate them slightly toward the midline, i.e. more inward, compared to the orientation of the monitors. Make sure that each eye can see the whole visual stimulus in the mirror without seeing any of it directly. Turning the blinders toward rather than away from the midline will minimize participants&#39; exposure to other visual input.</li>
	</ol>
	</li>
	<li>Software calibration
	<ol>
		<li>Since participants may vary in their eye position relative to the mirrors despite the use of a head rest, calibrate further before doing experiments. This part is most easily done in the software, i.e. without moving the setup&#39;s parts any further. There are two possible methods.
		<ol>
			<li>For the first, present a dot on each of the two screens in alternation, and instruct the participant to eliminate the perceived position change by moving the dot on one of the screens (or both in opposite directions).</li>
			<li>For the second method, instruct the participant to align the frames of experimental stimuli instead of two dots so that both eyes&#39; visual fields critical to the particular experiment are aligned.</li>
		</ol>
		</li>
		<li>After applying either method, center the stimuli in the experiment on the resulting on-screen positions. Other aspects of setting up displays and stimuli for dichoptic presentation in general can be found elsewhere5.</li>
	</ol>
	</li>
</ol>

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T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Binocular+Eye+Tracking+in+Virtual+Reality+for+Inspection+Training.">Binocular Eye Tracking in Virtual Reality for Inspection Training.</a> Proc. 2000 Symp. Eye Track. Res. Appl. , 89-96 (2000).</li><li>Hayashi, R., Tanifuji, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Which+image+is+in+awareness+during+binocular+rivalry?+Reading+perceptual+status+from+eye+movements.">Which image is in awareness during binocular rivalry? Reading perceptual status from eye movements.</a> J. Vis. 12 (3), 5-5 (2012).</li><li>van Dam, L. C. J., van Ee, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Retinal+image+shifts,+but+not+eye+movements+per+se,+cause+alternations+in+awareness+during+binocular+rivalry.">Retinal image shifts, but not eye movements per se, cause alternations in awareness during binocular rivalry.</a> J. Vis. 6 (11), 3-3 (2006).</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+fusionShort+Title??.">Simulated disparity and peripheral blur interact during binocular fusionShort Title??.</a> J. Vis. 14 (8), 13-13 (2014).</li><li>Vinnikov, M., Allison, R. S., Fernandes, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Impact+of+depth+of+field+simulation+on+visual+fatigue:+Who+are+impacted?+and+how?.">Impact of depth of field simulation on visual fatigue: Who are impacted? and how?.</a> Int. J. Hum.-Comput. Stud. 91, 37-51 (2016).</li><li>Tsuchiya, N., Wilke, M., Fr&#228;ssle, S., Lamme, V. A. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=No-Report+Paradigms:+Extracting+the+True+Neural+Correlates+of+Consciousness.">No-Report Paradigms: Extracting the True Neural Correlates of Consciousness.</a> Trends Cogn. Sci. 19 (12), 757-770 (2015).</li><li>Naber, M., Fr&#228;ssle, S., Einh&#228;user, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Perceptual+Rivalry:+Reflexes+Reveal+the+Gradual+Nature+of+Visual+Awareness.">Perceptual Rivalry: Reflexes Reveal the Gradual Nature of Visual Awareness.</a> PLOS ONE. 6 (6), e20910 (2011).</li></ol>

The authors have nothing to disclose.

We present a step-by-step guide for the construction and use of an experimental setup that allows simultaneous tracking of the both eyes and dichoptic presentation of visual stimuli. In many situations where dichoptic stimulation is used, the critical issue preventing effective eye tracking is that the mirrors for dichoptic presentation block the sight of video-based eye trackers. This is resolved here by using infrared-transparent mirrors and an infrared-sensitive eye tracker. This setup allows researchers of 3D vision,...

Under normal viewing conditions each of our eyes receives a slightly different visual input. This input is then processed to produce one coherent, three-dimensional representation of the world. Dichoptic presentation, the practice of independently controlling the input presented to each of the two eyes, thus enables researchers to study how humans reconstruct a three-dimensional representation from two two-dimensional retinal images2,3,4. In addition, if the two eyes&#39; images are too dissimilar, this interocular combination fails, and observers instead report perception of only one of the images at a time while the other remains suppressed, in phenomena such as binocular rivalry5 and continuous flash suppression6. Researchers of such interocular suppression, too, use dichoptic presentation, in this case to examine questions related to topics like the neural locus of awareness7, perceptual selection8,9, and unconscious processing10.
Gaze and pupil dynamics are recorded for multiple purposes in research on human behavior and perception. Gaze direction can inform about, for instance, attention allocation11,10,13 and decision making14, while pupil size can reveal aspects of visual processing15,16, task engagement17, or fluid intelligence18.
Combining eye tracking with dichoptic presentation is useful in research into, for instance, three dimensional (3D) perception19,20,21,22 or ocular responses to visual input during interocular suppression23,24,25. For example, eye movements have been found to reveal unconscious processing without subjective perception during continuous flash suppression23. Clinical visual researchers can use the ability to track both eyes during dichoptic presentation to investigate ocular diseases that affect the two eyes asymmetrically, for example, to monitor the monocular and binocular visual distortions occurring in amblyopia26 and maculopathy27.
We recently described a setup1 that allows for the combination of high quality video-based eye tracking and dichoptic stimulation with little limitation on the size or color of the stimuli, and we evaluated its performance. Below we will summarize the construction and use of this setup.

<table border="0" cellpadding="0" cellspacing="0" width="1130">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:163px;">Mirrors in Setup 1</td>
			<td style="width:283px;">Edmund Optics</td>
			<td style="width:169px;">&#160;#64-452</td>
			<td style="width:516px;">dimensions 10.10 &#215; 12.70 cm; Reflectance: 400 ~ 690 nm; Transmission: 750 ~ 1200nm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:163px;">Mirrors in Setup 2</td>
			<td style="width:283px;">Edmund Optics</td>
			<td style="width:169px;">Item discontinued</td>
			<td>dimensions 10.10 &#215; 12.70 cm; Reflectance: 425 ~ 650 nm; Transmission: 800 ~ 1200nm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Other Mirror Option</td>
			<td style="width:283px;">Edmund Optics</td>
			<td>#62-634</td>
			<td>dimensions 12.50 &#215; 12.50 cm; Reflectance: 425 ~ 650 nm; Transmission: 800 ~ 1200nm</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:163px;">Eye Tracker in Setup 1</td>
			<td style="width:283px;">SR Research Ltd., Mississauga, Ontario, Canada</td>
			<td style="width:169px;">Eyelink 1000</td>
			<td>Transmission: 890 ~ 940 nm</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:163px;">Eye Tracker in Setup 2</td>
			<td style="width:283px;">The Eye Tribe Aps, Copenhagen, Denmark</td>
			<td style="width:169px;">Eye Tribe (item discontinued)</td>
			<td>Transmission: around 850 nm</td>
		</tr>
	</tbody>
</table>

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.

After the calibration described in the protocol, we performed a calibration-validation procedure without problems with the mirrors in place. The effectiveness of the method is clearly illustrated by Figure 5, which shows the camera&#39;s image (using a research end eye tracking system) with the mirrors in place. The two sets of parallel lines along participants&#39; nose and the lines above the eye brows are the edges of the mirrors but, nevertheless, the fac...

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

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. ...

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8.4K Views.  Michigan State University. 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.

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

Eye Tracking, Cortisol, and a Sleep vs. Wake Consolidation Delay: Combining Methods to Uncover an Interactive Effect of Sleep and Cortisol on Memory

Although rises in cortisol can benefit memory consolidation, as can sleep soon after encoding, there is currently a paucity of literature as to how these two factors may interact to influence consolidation. Here we present a protocol to examine the interactive influence of cortisol and sleep on memory consolidation, by combining three methods: eye tracking, salivary cortisol analysis, and behavioral memory testing across sleep and wake delays. To assess resting cortisol levels, participants gave a saliva sample before viewing negative and neutral objects within scenes. To measure overt attention, participants&#8217; eye gaze was tracked during encoding. To manipulate whether sleep occurred during the consolidation window, participants either encoded scenes in the evening, slept overnight, and took a recognition test the next morning, or encoded scenes in the morning and remained awake during a comparably long retention interval. Additional control groups were tested after a 20&#160;min&#160;delay in the morning or evening, to control for time-of-day effects. Together, results showed that there is a direct relation between resting cortisol at encoding and subsequent memory, only following a period of sleep. Through eye tracking, it was further determined that for negative stimuli, this beneficial effect of cortisol on subsequent memory may be due to cortisol strengthening the relation between where participants look during encoding and what they are later able to remember. Overall, results obtained by a combination of these methods uncovered an interactive effect of sleep and cortisol on memory consolidation.

We present a protocol used to discover an interactive effect between sleep and cortisol on memory consolidation, particularly for negative arousing images. Specifically, the experimental design utilizes eye tracking, salivary cortisol analysis, and behavioral memory testing &#8211; methods that can be used with both healthy and clinical participants.

Although rises in cortisol can benefit memory consolidation, as can sleep soon after encoding, there is currently a paucity of literature as to how these ...

Assessment of Murine Exercise Endurance Without the Use of a Shock Grid: An Alternative to Forced Exercise

Using laboratory mouse models, the molecular pathways responsible for the metabolic benefits of endurance exercise are beginning to be defined. The most common method for assessing exercise endurance in mice utilizes forced running on a motorized treadmill equipped with a shock grid. Animals who quit running are pushed by the moving treadmill belt onto a grid that delivers an electric foot shock; to escape the negative stimulus, the mice return to running on the belt. However, avoidance behavior and psychological stress due to use of a shock apparatus can interfere with quantitation of running endurance, as well as confound measurements of postexercise serum hormone and cytokine levels. Here, we demonstrate and validate a refined method to measure running endurance in na&#239;ve C57BL/6 laboratory mice on a motorized treadmill without utilizing a shock grid. When mice are preacclimated to the treadmill, they run voluntarily with gait speeds specific to each mouse. Use of the shock grid is replaced by gentle encouragement by a human operator using a tongue depressor, coupled with sensitivity to the voluntary willingness to run on the part of the mouse. Clear endpoints for quantifying running time-to-exhaustion for each mouse are defined and reflected in behavioral signs of exhaustion such as splayed posture and labored breathing. This method is a humane refinement which also decreases the confounding effects of stress on experimental parameters.

A method to assess exercise endurance in laboratory mice without the use of a shock grid is demonstrated. This method is a humane refinement that can decrease the confounding effects of stress on experimental parameters.

Using laboratory mouse models, the molecular pathways responsible for the metabolic benefits of endurance exercise are beginning to be defined. The most ...

A Dual Task Procedure Combined with Rapid Serial Visual Presentation to Test Attentional Blink for Nontargets

When viewers search for targets in a rapid serial visual presentation (RSVP) stream, if two targets are presented within about 500 msec of each other, the first target may be easy to spot but the second is likely to be missed. This phenomenon of attentional blink (AB) has been widely studied to probe the temporal capacity of attention for detecting visual targets. However, with the typical procedure of AB experiments, it is not possible to examine how the processing of non-target items in RSVP may be affected by attention. This paper describes a novel dual task procedure combined with RSVP to test effects of AB for nontargets at varied stimulus onset asynchronies (SOAs). In an exemplar experiment, a target category was first displayed, followed by a sequence of 8 nouns. If one of the nouns belonged to the target category, participants would respond &#8216;yes&#8217; at the end of the sequence, otherwise participants would respond &#8216;no&#8217;. Two 2-alternative forced choice memory tasks followed the response to determine if participants remembered the words immediately before or after the target, as well as a random word from another part of the sequence. In a second exemplar experiment, the same design was used, except that 1) the memory task was counterbalanced into two groups with SOAs of either 120 or 240 msec and 2) three memory tasks followed the sequence and tested remembrance for nontarget nouns in the sequence that could be anywhere from 3 items prior the target noun position to 3 items following the target noun position. Representative results from a previously published study demonstrate that our procedure can be used to examine divergent effects of attention that not only enhance targets but also suppress nontargets. Here we show results from a representative participant that replicated the previous finding.&#160;

This paper describes a novel dual task procedure combined with Rapid Serial Visual Presentation to look at attentional blink at varied stimulus onset asynchronies. This experimental procedure differed from others in that it tested attentional blink for nontargets.

When viewers search for targets in a rapid serial visual presentation (RSVP) stream, if two targets are presented within about 500 msec of each other, the ...

Eye-Tracking Control to Assess Cognitive Functions in Patients with Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder with pathological involvement of upper and lower motoneurons, subsequently leading to progressive loss of motor and speech abilities. In addition, cognitive functions are impaired in a subset of patients. To evaluate these potential deficits in severely physically impaired ALS patients, eye-tracking is a promising means to conduct cognitive tests. The present article focuses on how eye movements, an indirect means of communication for physically disabled patients, can be utilized to allow for detailed neuropsychological assessment. The requirements, in terms of oculomotor parameters that have to be met for sufficient eye-tracking in ALS patients are presented. The properties of stimuli, including type of neuropsychological tests and style of presentation, best suited to successfully assess cognitive functioning, are also described. Furthermore, recommendations regarding procedural requirements are provided. Overall, this methodology provides a reliable, easy to administer and fast approach for assessing cognitive deficits in patients who are unable to speak or write such as patients with severe ALS. The only confounding factor might be deficits in voluntary eye movement control in a subset of ALS patients.

Cognitive deficits are common in about one third of patients with amyotrophic lateral sclerosis, a neurological condition leading to progressive impairments in speech and movement abilities. To conduct cognitive tests in patients unable to speak or write a reliable and easy to administer eye-tracking paradigm was developed.

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder with pathological involvement of upper and lower motoneurons, subsequently leading to ...

The Other End of the Leash: An Experimental Test to Analyze How Owners Interact with Their Pet Dogs

It has been suggested that the way in which owners interact with their dogs can largely vary and influence the dog-owner bond, but very few objective studies, so far, have addressed how the owner interacts with the dog. The goal of the present study was to record dog owners&#39; interaction styles by means of objective observation and coding. The experiment included eight standardized situations in which owners of pet dogs were asked to perform specific tasks including both positive (i.e. playing, teaching a new task, showing a preference towards an object in a food searching task, greeting after separation) and potentially distressing tasks (i.e. physical restriction during DNA sampling, putting a T-shirt onto the dog, giving basic obedience commands while the dog was distracted). The video recordings were coded off-line using a specifically designed coding scheme including scores for communication, social support, warmth, enthusiasm, and play style, as well as frequency of behaviors like petting, praising, commands, and attention sounds. Exploratory Factor Analysis of the 20 variables measured revealed 3 factors, labeled as Owner Warmth, Owner Social Support, and Owner Control, which can be viewed as analogues to parenting style dimensions. The experimental procedure introduced here represents the first standardized measure of interaction styles of dog owners. The methodology presented here is a useful tool to investigate individual variation in the interaction style of pet dog owners that can be used to explain differences in the dog-human relationship, dogs&#39; behavioral outcomes, and dogs stress coping strategies, all crucial elements both from a theoretical and applied point of view.

This article presents eight different experimental tasks, mirroring the everyday life of dogs and owners, used to analyze how owners interact with their dogs in a standardized way. The tasks included both positive (e.g. play) and negative (potentially stressful) situations (e.g. physical restriction).

It has been suggested that the way in which owners interact with their dogs can largely vary and influence the dog-owner bond, but very few objective ...

Using Rapid Serial Visual Presentation to Measure Set-Specific Capture, a Consequence of Distraction While Multitasking

This method uses a rapid serial visual presentation (RSVP) paradigm to measure the cost of distraction when participants maintain multiple search goals. The protocol identifies two types of distraction within a single task - contingent attentional capture and set-specific capture - that represent different types of limitations of cognitive processing. Participants search for letters in two or more &#34;target&#34; ink colors (e.g., green and orange) within a continuous RSVP stream of heterogeneously colored letters, while ignoring two peripheral RSVPs of letters. Upon detecting a target, participants are to identify the letter. On some trials, target-colored distractors appear in the periphery just prior to the presentation of a target, causing a drop in target identification performance. Contingent attentional capture is observed by examining performance on trials in which the peripheral distractor is the same color as the target on that trial (e.g., both orange). Set-specific capture is represented by performance on trials in which the peripheral distractor is target-colored (e.g., orange), but not the same color as the target on that trial (e.g., green.) By varying the amount of time (i.e., the number of stimuli appearing) between the presentation of the distractor and the target, researchers can observe how participants recover from these distraction costs over time. As compared to static displays that are often used to measure contingent attentional capture, the dynamic display produces much larger effects, allowing the researcher to identify subtle effects of smaller manipulations. An unusual aspect of our design is that it employs a continuous display; &#34;filler&#34; stimuli connect one trial to the next seamlessly, and participants respond during this interval whenever they detect a target. The continuous display reduces chance performance to near-zero levels (rather than 50%) and provides researchers with a more sensitive measure of performance differences across trial types.

This method uses a dynamic visual display to index costs of distraction during visual search, including both &#34;contingent attentional capture&#34; and &#34;set-specific capture,&#34; which is a cost of distraction that occurs when the participants maintain multiple search goals simultaneously. This method has revealed basic mechanisms and limitations of visual attention.

This method uses a rapid serial visual presentation (RSVP) paradigm to measure the cost of distraction when participants maintain multiple search goals. ...

Olfactory Context Dependent Memory: Direct Presentation of Odorants

Information is retrieved more effectively when the retrieval occurs in the same context as that in which the information was first encoded. This is termed context dependent memory (CDM). One category of cues that have been shown to effectively produce CDM effects are odors. However, it is unclear what the boundary conditions of these CDM effects are. In particular, given that olfaction has been called an implicit sense, it is possible that odors are only effective mnemonic cues when they are presented in the background. This assertion seems even more likely given that previous research has shown odors to be poor cues during paired associate memory tests, where odors are in the focus of attention as mnemonic cues for other information. In order to determine whether odors are only effective contextual mnemonic cues when presented outside the central focus of an observer, an olfactory CDM experiment was performed in which odorants were presented directly, rather than ambiently. Direct presentation was accomplished with the aid of an olfactometer. The olfactometer not only allows for direct presentation of odorants, but provides other methodological benefits, including the allowance of trial by trial manipulations of odorant presentations and, relatedly, time-specific releases of odorants. The presence of the same odor during both encoding and retrieval enhanced memory performance, regardless of whether the odor was presented ambiently or directly. This finding can serve as a basis for future olfactory CDM research which can utilize the benefits of direct presentation.

The use of an olfactometer for directly presenting odorants opens exciting opportunities for researchers of olfactory memory. The current paper discusses issues related to this methodology as related to a previously published experiment on olfactory context dependent memory.

Information is retrieved more effectively when the retrieval occurs in the same context as that in which the information was first encoded. This is termed ...

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 ...

Efficiently Recording the Eye-Hand Coordination to Incoordination Spectrum

The objective analysis of eye movements has a significant history and has been long proven to be an important research tool in the setting of brain injury. Quantitative recordings have a strong capacity to screen diagnostically. Concurrent examinations of the eye and upper limb movements directed toward shared functional goals (e.g., eye-hand coordination) serve as an additional robust biomarker-laden path to capture and interrogate neural injury, including acquired brain injury (ABI). While quantitative dual-effector recordings in 3-D afford ample opportunities within ocular-manual motor investigations in the setting of ABI, the feasibility of such dual recordings for both eye and hand is challenging in pathological settings, particularly when approached with research-grade rigor. Here we describe the integration of an eye tracking system with a motion tracking system intended primarily for limb control research to study a natural behavior. The protocol enables the investigation of unrestricted, three-dimensional (3D) eye-hand coordination tasks. More specifically, we review a method to assess eye-hand coordination in visually guided saccade-to-reach tasks in subjects with chronic middle cerebral artery (MCA) stroke and compare them to healthy controls. Special attention is paid to the specific eye- and limb-tracking system properties in order to obtain high fidelity data from participants post-injury. Sampling rate, accuracy, permissible head movement range given anticipated tolerance and the feasibility of use were several of the critical properties considered when selecting an eye tracker and an approach. The limb tracker was selected based on a similar rubric but included the need for 3-D recording, dynamic interaction and a miniaturized physical footprint. The quantitative data provided by this method and the overall approach when executed correctly has tremendous potential to further refine our mechanistic understanding of eye-hand control and help inform feasible diagnostic and pragmatic interventions within the neurological and rehabilitative practice.&#160;

Cerebral injury can damage both ocular and somatic motor systems. Characterization of motor control post-injury affords biomarkers that assist in disease detection, monitoring, and prognosis. We review a method to measure eye-hand movement control in health and in pathologic incoordination, with look-and-reach paradigms to assess coordination between eye and hand.

The objective analysis of eye movements has a significant history and has been long proven to be an important research tool in the setting of brain ...

Modified Blood Collection from Tail Veins of Non-anesthetized Mice with a Vacuum Blood Collection System and Eyeglass Magnifier

Blood sample collection is the basis of experimental animal research. It is of importance to obtain adequate blood samples for various research purposes. The tail veins of mice are small, and it is sometimes difficult to obtain the required blood volume by conventional puncture methods. This study investigates the superiority of repeated blood sample collection from tail veins of mice through use of a vacuum blood collection system and eyeglass magnifier (experimental group) compared to conventional blood sampling methods (conventional group), performed by beginners and experts, respectively. With the help of an eyeglass magnifier, a butterfly needle tip is inserted into the tail vein of each mouse in the experimental group. When the vein is penetrated successfully, a blood sample is collected in the vacuum collection tube by insertion of the rubber end of a butterfly needle into the vacuum blood collection tube. The plunger is then used to collect blood without the help of the eyeglass magnifier in the conventional group. Success rates of blood sample collection by the beginners and experts were shown to be 70% vs. 100% (p &#60; 0.01) in the experimental group and 35% vs. 85% (p &#60; 0.01) in the conventional group. For both beginners and experts, puncture times required for obtaining required blood sample were significantly lower in the experimental group compared to the conventional group (2.40 &#177; 0.75 vs. 2.90 &#177; 0.31, p &#60; 0.05; 1.15 &#177; 0.37 vs. 1.55 &#177; 0.76, p &#60; 0.05). In conclusion, the presented blood sampling technique is feasible and easy to practice and enables frequent sampling of adequate blood volumes from non-anesthetized mice.&#160;

This study reports blood sampling from tail vein in mice using a vacuum extraction tube system with eyeglass magnifier. Our method is easy to practice and could be used for repeat blood sampling in mice.

Blood sample collection is the basis of experimental animal research. It is of importance to obtain adequate blood samples for various research purposes. ...