This study was supported by Capital&#39;s Fund for Health Improvement and Research (No. 2018-2Z-4076) and Peking University First Hospital SEED Research Funds (2019SF31).

The protocol described here was approved by the Ethical Committee of Peking University First Hospital (PKUFH 2018-223). The procedures adhered to the tenets of the Declaration of Helsinki for research involving human subjects. The study format was described, and informed consent was obtained from the parents of the participants.
1. Preparation of the apparatus
NOTE: The AACP components were set up in a mildly illuminated test room. Drapes were pulled in the room to avoid interference from sunlight. A display system, a recording system, and an analysis system were the three components of the AACP (Figure 1).
<ol>
	<li>Set up a display system, a 28 inch liquid-crystal display monitor (62.208 cm x 34.992 cm screen, 3840 pixels x 2160 pixels, 0.162 mm/pixel, 30 Hz frame rate). Place the display monitor on a table that can be raised. Linearize the screen luminance by an 8-bit look-up table. Set the luminance at 1 cd/m2, 200 cd/m2, and 400 cd/m2 for black, mid-gray, and white, respectively.</li>
	<li>Place two side panels on either side of the screen to reduce distractions for the children being tested.</li>
	<li>Set up a recording system, a high-definition pro webcam with a resolution of 1080 pixels/30 fps. 
	NOTE: The webcam records image sequences of testers&#39; behaviors, each cropped at 1280 pixels x 720 pixels. During automated acuity testing, one time-stamped webcam image is obtained every 200 ms for synchronization.</li>
	<li>Connect the display monitor and webcam to a computer, the analysis system. Ensure that the webcam is located in the center, directly below the screen, and is able to be adjusted as needed. 
	NOTE: The monitor and webcam are either integrated with the computer (a laptop or desktop PC) or are separate devices that are then attached to a computer.</li>
	<li>Install the AACP procedure software on the computer for the presentation of stimuli and the analysis of eye movements. The AACP procedure software (China National Invention Patents, No. 201910865074.4 and No. 201510919621.4) comprises a stimulus displaying module, a vision testing module, and a testing result processing module.</li>
	<li>Set the visual stimuli as a 12 cm x 12 cm square-wave grating with different period/degree (cpd) spatial frequencies and a contrast ratio of 1.00. Ensure that the stimulus is displayed randomly in the center of the left or right portion of the screen, and that the rest of the screen shows a luminance-matched gray area similar to the TACII. 
	&#8203;NOTE: At the detection distance of 55 cm (which is consistent with that of TACII), the stimuli were approximately the same (due to pixel size limitations) as those on printed TACII cards (16 cards, 1/2 octave).</li>
</ol>
2. Eye-tracking calibration
<ol>
	<li>Obtain informed consent from the parents, and describe the study format to them.</li>
	<li>Position the child at a distance of 55 cm from the display monitor. Let the child sit alone on a chair or, preferably, on the parent&#39;s lap. If the child sits alone, let the parent sit alongside the child.</li>
	<li>Adjust the position of the lifting table and place it with the monitor. Arrange the screen perpendicular to the child&#39;s eyes.</li>
	<li>Adjust the position of the webcam to ensure that the child&#39;s face is visible in the recording system and to avoid capturing faces other than the child&#39;s.</li>
	<li>Prior to starting the procedure, inform the child that they will be watching the screen. Instruct the parent to prompt the child to look at the screen when the child is not paying attention. No specific instructions are necessary during the test.</li>
	<li>Open the AACP procedure software. Type the child&#39;s information into the software (name, sex, age).</li>
	<li>Click on the Start button. The software starts the calibration procedure. A graphics interchange format (GIF) image (2.0736 cm x 2.0736 cm, 128 x 128 pixels) appears against the white background in the center of the screen (Figure 2). The image and background music appears simultaneously. This stimulus is presented for at least 3 s. The analysis system simultaneously determines whether the child&#39;s line of sight is fixated on the image. If no gaze data are available within 1 min during this presentation, the screen presents another cartoon GIF image. When gaze coordinates are detected within this region, the test procedure starts without the actions of the tester and runs automatically.</li>
</ol>
3. Testing procedure
<ol>
	<li>Present the initial grating. The spatial frequencies of the gratings range from 0.33-30.0 cpd in 1/2 octave steps. Determine the initial grating by the child&#39;s age, as in the TACII test.</li>
	<li>Present the initial grating for 1,000 ms, which is the length of a trial. Then, present a blank screen for 200 ms. Present the same stimulus again, followed by a blank screen again. Present the grating of the same spatial frequency set three times.</li>
	<li>During execution of the procedure, let the webcam record the child&#39;s facial pictures. The software uses these pictures to analyze their watching behavior. The vision testing program checks the eye movement responses with the criteria stated in Table 1 to determine whether the stimulus has been seen (Figure 3).</li>
	<li>Let the testing result processing program present the subsequent stimulus, according to the protocol shown in Figure 411.</li>
	<li>After every three trials, present a GIF image (with background music) as a visual reward to maintain the child&#39;s interest. If no gaze data are usable (e.g., if the child turned around or had their eyes closed) within 1 min of the GIF image presentation, stop the test. This test outputs no result.</li>
	<li>After performing steps 3.4 and 3.5, analyze the grating acuity results for the child outputted by the software programs.</li>
</ol>

An Automated Assessment of Visual Acuity in Infants and Toddlers

<ol>
	<li>Teller, D. Y., McDonald, M. A., Preston, K., Sebris, S. L., Dobson, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Assessment+of+visual+acuity+in+infants+and+children:+the+acuity+card+procedure.">Assessment of visual acuity in infants and children: the acuity card procedure.</a> Developmental Medicine and Child Neurology. 28 (6), 779-789 (1986).</li><li>Teller, D. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+forced-choice+preferential+looking+procedure:+a+psychophysical+technique+for+use+with+human+infants.">The forced-choice preferential looking procedure: a psychophysical technique for use with human infants.</a> Infant Behavior and Development. 2, 135-153 (1979).</li><li>Preston, K. L., McDonald, M., Sebris, S. L., Dobson, V., Teller, D. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Validation+of+the+acuity+card+procedure+for+assessment+of+infants+with+ocular+disorders.">Validation of the acuity card procedure for assessment of infants with ocular disorders.</a> Ophthalmology. 94 (6), 644-653 (1987).</li><li>Mohn, G., vanHof-van Duin, J., Fetter, W. P., de Groot, L., Hage, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Acuity+assessment+of+non-verbal+infants+and+children:+clinical+experience+with+the+acuity+card+procedure.">Acuity assessment of non-verbal infants and children: clinical experience with the acuity card procedure.</a> Developmental Medicine and Child Neurology. 30 (2), 232-244 (1988).</li><li>Cavallini, A., 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=Visual+acuity+in+the+first+two+years+of+life+in+healthy+term+newborns:+an+experience+with+the+teller+acuity+cards.">Visual acuity in the first two years of life in healthy term newborns: an experience with the teller acuity cards.</a> Functional Neurology. 17 (2), 87-92 (2002).</li><li>Clifford, C. E., Haynes, B. M., Dobson, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Are+norms+based+on+the+original+teller+acuity+cards+appropriate+for+use+with+the+new+teller+acuity+cards+II.">Are norms based on the original teller acuity cards appropriate for use with the new teller acuity cards II.</a> Journal of American Association for Pediatric Ophthalmology and Strabismus. 9 (5), 475-479 (2005).</li><li>Jones, P. R., Kalwarowsky, S., Atkinson, J., Braddick, O. J., Nardini, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Automated+measurement+of+resolution+acuity+in+infants+using+remote+eye-tracking.">Automated measurement of resolution acuity in infants using remote eye-tracking.</a> Investigative Ophthalmology &amp; Visual Science. 55 (12), 8102-8110 (2014).</li><li>Hathibelagal, A. R., Leat, S. J., Irving, E. L., Nandakumar, K., Eizenman, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measuring+infant+visual+acuity+with+gaze+tracker+monitored+visual+fixation.">Measuring infant visual acuity with gaze tracker monitored visual fixation.</a> Optometry and Vision Science. 92 (7), 823-833 (2015).</li><li>Barsingerhorn, A. D., Boonstra, F. N., Goossens, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Saccade+latencies+during+a+preferential+looking+task+and+objective+scoring+of+grating+acuity+in+children+with+and+without+visual+impairments.">Saccade latencies during a preferential looking task and objective scoring of grating acuity in children with and without visual impairments.</a> Acta Ophthalmologica. 97 (6), 616-625 (2019).</li><li>Vrabi&#269;, N., Juro&#353;, B., Tekav&#269;i&#269; Pompe, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Automated+visual+acuity+evaluation+based+on+preferential+looking+technique+and+controlled+with+remote+eye+tracking.">Automated visual acuity evaluation based on preferential looking technique and controlled with remote eye tracking.</a> Ophthalmic Research. 64 (3), 389-397 (2021).</li><li>Wen, J., Yang, B., Li, X., Cui, J., Wang, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Automated+assessment+of+grating+acuity+in+infants+and+toddlers+using+an+eye-tracking+system.">Automated assessment of grating acuity in infants and toddlers using an eye-tracking system.</a> Journal of Vision. 22 (12), 8 (2022).</li><li>Leone, J. F., Mitchell, P., Kifley, A., Rose, K. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Normative+visual+acuity+in+infants+and+preschool-aged+children+in+Sydney.">Normative visual acuity in infants and preschool-aged children in Sydney.</a> Acta Ophthalmologica. 92 (7), e521-e529 (2014).</li><li>Clifford-Donaldson, C. E., Haynes, B. M., Dobson, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Teller+Acuity+Card+norms+with+and+without+use+of+a+testing+stage.">Teller Acuity Card norms with and without use of a testing stage.</a> Journal of AAPOS. 10 (6), 547-551 (2006).</li><li>Robinson, J., Moseley, M., Fielder, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Grating+acuity+cards-spurious+resolution+and+the+edge+artifact.">Grating acuity cards-spurious resolution and the edge artifact.</a> Clinical Vision Sciences. 3 (4), 285-288 (1988).</li></ol>

The authors have made the following disclosures: BK.Y., XQ.L., JS.C., and L.W.: China National Invention Patent "A method and system for face detection and pupil localization in continuous video frames" (CN201910865074.4); XQ.L., BK.Y., JS.C., and L.W.: China National Invention Patent "Vision automatic testing system" (No. 201510919621.4).

Several studies7,8,9,10 based on the eye-tracking method have shown the value of this method in evaluating infants and young children who have difficulty in verbal communication. However, the number of participants in previous studies is relatively small. Only 30 infants under 12 months of age were tested by the ACTIVE procedure, which was developed by Jones et al.7. The...

The infantile period is a critical period for visual development. Visual problems that arise early in life can have a significant impact on a child&#39;s development. It is important to be able to perform a quantitative visual assessment in infants, which can help detect early vision problems. However, because infants are not cognitively developed or expressive enough to recognize visual acuity chart symbols, such as letters or graphs, measuring their visual acuity is difficult. The current gold standard for infant vision assessment is the acuity card procedure1 based on the preferential looking test2. However, because this method requires experienced testers to judge visual acuity by observing the child&#39;s eye movements3,4,5,6, it is limited by the experience of the testers4,5. Therefore, acuity card procedures, such as Teller Acuity Cards (TACs)5,6, remain a subjective method. Thus, there is a need for a method that can quantitatively measure visual acuity in infants and young children, that can be used without the need for verbal communication and that is not limited by requiring experienced testers.
The invention and use of the remote eye tracker enabled an automated acuity measuring system to be developed. In previous studies, eye-tracking methods have been used as a tool for visual function evaluation in children7,8,9,10. A remote eye tracker can be used for gaze tracking and is a substitute for a tester&#39;s observation of a child&#39;s eye movements. The ACTIVE procedure7 and AVAT procedure10 are fully automated visual acuity tests with a remote eye tracker; they have yielded comparable visual acuity results to the Keeler Acuity Cards test in healthy infants and young children. As opposed to other recent studies, we used a webcam instead of a remote eye tracker to capture the child&#39;s gaze. We invented an eye movement data automatic acquisition method based on computer vision. The procedure combined the eye movement acquisition method with the preferential looking technique in assessing visual function in children.
This paper aims to present a novel automated method, which can evaluate visual acuity in young children, called the automated acuity card procedure (AACP). This procedure is particularly useful for infants and younger children who have not yet acquired sufficient communication skills. The key aspect is that visual responses can be quantitated to yield grating acuity in infants and young children. Grating acuity measurement enables the detection of visual pathologies and plays an important role in subsequent medical management.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>AACP procedure software</td>
			<td>In-house</td>
			<td>In-house</td>
			<td>The AACP procedure software (China National Invention Patents, No. 201910865074.4 and No. 201510919621.4) comprises a stimulus displaying module, a vision testing module, and a testing result processing module.</td>
		</tr>
		<tr>
			<td>Computer processor</td>
			<td>Intel Corporation, Santa Clara, CA, USA&#160;</td>
			<td>Intel CORE i7-6500U processor</td>
			<td>Analysis system</td>
		</tr>
		<tr>
			<td>Display monitor</td>
			<td>InnoLux Co., Ltd., China</td>
			<td>InnoLux M280DGJ-L30&#160;</td>
			<td>Display system</td>
		</tr>
		<tr>
			<td>Webcam</td>
			<td>Logitech International S.A., Lausanne, Switzerland&#160;</td>
			<td>Logitech C920 high-definition pro webcam</td>
			<td>Recording system</td>
		</tr>
	</tbody>
</table>

an automated method for assessing visual acuity in infants and toddlers using an eye-tracking system

Visual acuity measurement is an important visual function test to perform in infancy and childhood. However, accurate visual acuity measurement in infants is difficult because of deficiencies in their communication ability. This paper presents a novel automated method to assess visual acuity in children (5-36 months old). This method, the automated acuity card procedure (AACP), uses a webcam for eye tracking and recognizes children's watching behaviors automatically. A two-choice preferential-looking test is performed when the tested child watches the visual stimuli shown on a high-resolution digital display screen. When the tested child watches the stimuli, their facial pictures are recorded by the webcam. These pictures are used by the set computer program to analyze their watching behavior. With this procedure, the child's eye movement responses to different stimuli are measured, and their visual acuity is assessed without communication. By comparing the results with grating acuity obtained by Teller Acuity Cards (TACs), AACP performance is deemed comparable to that of TACs.

The AACP was applied to one group of children11: 155 normally developing infants and toddlers (5 to 36 months old, based on gestational age). In a previously published study, the grating acuity results obtained by the AACP were compared with those obtained by TACII. The results obtained by these two procedures are significantly correlated (r153 = 0.83, p &#60; 0.001). Only 10.32% (16 of 155) of the children&#39;s results differed by more than one octave. Among them, eight child...

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Author Spotlight: An Automated Method for Assessing Visual Acuity in Infants and Toddlers Using an Eye-Tracking System  

In this paper, we present a novel automated method for assessing visual acuity in infants and toddlers by using an eye-tracking system.

An Automated Method for Assessing Visual Acuity in Infants and Toddlers Using an Eye-Tracking System

Visual acuity measurement is an important visual function test to perform in infancy and childhood. However, accurate visual acuity measurement in infants ...

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2.5K Views.  Peking University. In this paper, we present a novel automated method for assessing visual acuity in infants and toddlers by using an eye-tracking system.

Video: Author Spotlight: An Automated Method for Assessing Visual Acuity in Infants and Toddlers Using an Eye-Tracking System  

Experimental Assessment of Mouse Sociability Using an Automated Image Processing Approach

Mouse is the preferred model organism for testing drugs designed to increase sociability. We present a method to quantify mouse sociability in which the test mouse is placed in a standardized apparatus and relevant behaviors are assessed in three different sessions (called session I, II, and III).
The apparatus has three compartments (see Figure 1), the left and right compartments contain an inverted cup which can house a mouse (called &#34;stimulus mouse&#34;).
In session I, the test mouse is placed in the cage and its mobility is characterized by the number of transitions made between compartments. In session II, a stimulus mouse is placed under one of the inverted cups and the sociability of the test mouse is quantified by the amounts of time it spends near the cup containing the enclosed stimulus mouse vs. the empty inverted cup. In session III, the inverted cups are removed and both mice interact freely. The sociability of the test mouse in session III is quantified by the number of social approaches it makes toward the stimulus mouse and by the number of times it avoids a social approach by the stimulus mouse.
The automated evaluation of the movie detects the nose of the test mouse, which allows the determination of all described sociability measures in session I and II (in session III, approaches are identified automatically but classified manually). To find the nose, the image of an empty cage is digitally subtracted from each frame of the movie and the resulting image is binarized to identify the mouse pixels. The mouse tail is automatically removed and the two most distant points of the remaining mouse are determined; these are close to nose and base of tail. By analyzing the motion of the mouse and using continuity arguments, the nose is identified.
<img alt="Figure 1" src="/files/ftp_upload/52508/52508fig1.jpg" /> 
Figure 1. Assessment of Sociability During 3 sessions. Session I (top): Acclimation of test mouse to the cage. Session II (middle): Test mouse moving freely in the cage while the stimulus mouse is enclosed in an inverted cup. Session III (bottom): Both test mouse and stimulus mouse are allowed to move freely and interact with each other.

This protocol describes a method to quantify mouse sociability. Mice are videotaped as they move and interact in a special cage. Movie processing allows for the automated quantification of sociability with excellent accuracy and reliability.

Mouse is the preferred model organism for testing drugs designed to increase sociability. We present a method to quantify mouse sociability in which the ...

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 ...

The Knob Supination Task: A Semi-automated Method for Assessing Forelimb Function in Rats

Tasks that accurately measure dexterity in animal models are critical to understand hand function. Current rat behavioral tasks that measure dexterity largely use video analysis of reaching or food manipulation. While these tasks are easy to implement and are robust across disease models, they are subjective and laborious for the experimenter. Automating traditional tasks or creating new automated tasks can make the tasks more efficient, objective, and quantitative. Since rats are less dexterous than primates, central nervous system (CNS) injury produces more subtle deficits in dexterity, however, supination is highly affected in rodents and crucial to hand function in primates. Therefore, we designed a semi-automated task that measures forelimb supination in rats. Rats are trained to reach and grasp a knob-shaped manipulandum and turn the manipulandum in supination to receive a reward. Rats can acquire the skill within 20 &plusmn; 5 days. While the early part of training is highly supervised, much of the training is done without direct supervision. The task reliably and reproducibly captures subtle deficits after injury and shows functional recovery that accurately reflects clinical recovery curves. Analysis of data is performed by specialized software through a graphical user interface that is designed to be intuitive. We also give solutions to common problems encountered during training, and show that minor corrections to behavior early in training produce reliable acquisition of supination. Thus, the knob supination task provides efficient and quantitative evaluation of a critical movement for dexterity in rats.

This manuscript describes a semi-automated task that quantifies supination in rats. Rats reach, grasp, and supinate a spherical manipulandum. The rat is rewarded with a pellet if the turn angle exceeds a criterion set by the user. This task increases throughput, sensitivity to injury, and objectivity compared to traditional tasks.

Tasks that accurately measure dexterity in animal models are critical to understand hand function. Current rat behavioral tasks that measure dexterity ...

Use of a Video Scoring Anchor for Rapid Serial Assessment of Social Communication in Toddlers

Reciprocal social behavior (RSB), an early-emerging capacity to engage in social contingency&#8212;which is foundational for both social learning and social competency&#8212;is hypothesized to be disrupted in autism spectrum disorder (ASD). The ability to quantify the full range of RSB during the toddler period, when core symptoms of ASD often arise, is pivotal for evaluating early risk for ASD, characterizing social development, and tracking response to early interventions. However, important parameters of variation in RSB&#8212;especially prior to the development of verbal language&#8212;can be nuanced and difficult to characterize using questionnaire-based methods. To address this challenge, we developed a system for measuring quantitative variation in RSB in toddlers (ages 18 - 30 months) that incorporated not only standard questionnaire data from caregivers but also a novel set of video-referenced items, through which a respondent compares the behavior of a subject to that observed in a short video of a young child manifesting a highly competent level of social communication. Testing of this measure in a general population sample of twins confirmed that both the video-referenced items and the RSB Total Score (video-referenced items plus non-video-referenced items) displayed unimodal, continuous distributions, strong internal consistency, marked preservation of individual differences, and extremely high heritability. In addition, video-referenced items were particularly sensitive to quantifying incremental changes in social communication, a major element of RSB, over the course of early childhood development. Scores on the vrRSB clearly differentiated children with and without ASD and these data comprise an initial validation of this promising method for quantifying early RSB&#8212;cross-sectionally, over time, and as a function of early intervention.

Here we present a protocol for administration of the video-referenced rating of reciprocal social behavior (vrRSB) using a paper or online version. This survey quantifies RSB, a prerequisite for social competence, in toddlers through &#34;video-referenced&#34; items whereby a subject is compared to a reference child shown in a three-minute video.

Reciprocal social behavior (RSB), an early-emerging capacity to engage in social contingency&#8212;which is foundational for both social learning and ...

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 ...

An Automated Method to Determine the Performance of Drosophila in Response to Temperature Changes in Space and Time

Temperature is a ubiquitous environmental factor that affects how species distribute and behave. Different species of Drosophila fruit flies have specific responses to changing temperatures according to their physiological tolerance and adaptability. Drosophila flies also possess a temperature sensing system that has become fundamental to understanding the neural basis of temperature processing in ectotherms. We present here a temperature-controlled arena that permits fast and precise temperature changes with temporal and spatial control to explore the response of individual flies to changing temperatures. Individual flies are placed in the arena and exposed to pre-programmed temperature challenges, such as uniform gradual increases in temperature to determine reaction norms or spatially distributed temperatures at the same time to determine preferences. Individuals are automatically tracked, allowing the quantification of speed or location preference. This method can be used to rapidly quantify the response over a large range of temperatures to determine temperature performance curves in Drosophila or other insects of similar size. In addition, it can be used for genetic studies to quantify temperature preferences and reactions of mutants or wild-type flies. This method can help uncover the basis of thermal speciation and adaptation, as well as the neural mechanisms behind temperature processing.

An Automated Method to Determine the Performance of Drosophila in Response to Temperature Changes in Space and Time

Here we present a protocol to automatically determine the locomotor performance of Drosophila at changing temperatures using a programmable temperature-controlled arena that produces fast and accurate temperature changes in time and space.

Temperature is a ubiquitous environmental factor that affects how species distribute and behave. Different species of Drosophila fruit flies have specific ...

Gaze in Action: Head-mounted Eye Tracking of Children's Dynamic Visual Attention During Naturalistic Behavior

Young children's visual environments are dynamic, changing moment-by-moment as children physically and visually explore spaces and objects and interact with people around them. Head-mounted eye tracking offers a unique opportunity to capture children's dynamic egocentric views and how they allocate visual attention within those views. This protocol provides guiding principles and practical recommendations for researchers using head-mounted eye trackers in both laboratory and more naturalistic settings. Head-mounted eye tracking complements other experimental methods by enhancing opportunities for data collection in more ecologically valid contexts through increased portability and freedom of head and body movements compared to screen-based eye tracking. This protocol can also be integrated with other technologies, such as motion tracking and heart-rate monitoring, to provide a high-density multimodal dataset for examining natural behavior, learning, and development than previously possible. This paper illustrates the types of data generated from head-mounted eye tracking in a study designed to investigate visual attention in one natural context for toddlers: free-flowing toy play with a parent. Successful use of this protocol will allow researchers to collect data that can be used to answer questions not only about visual attention, but also about a broad range of other perceptual, cognitive, and social skills and their development.

Young children do not passively observe the world, but rather actively explore and engage with their environment. This protocol provides guiding principles and practical recommendations for using head-mounted eye trackers to record infants' and toddlers' dynamic visual environments and visual attention in the context of natural behavior.

Young children's visual environments are dynamic, changing moment-by-moment as children physically and visually explore spaces and objects and interact ...

Simultaneous Eye Tracking and Single-Neuron Recordings in Human Epilepsy Patients

Intracranial recordings from patients with intractable epilepsy provide a unique opportunity to study the activity of individual human neurons during active behavior. An important tool for quantifying behavior is eye tracking, which is an indispensable tool for studying visual attention. However, eye tracking is challenging to use concurrently with invasive electrophysiology and this approach has consequently been little used. Here, we present a proven experimental protocol to conduct single-neuron recordings with simultaneous eye tracking in humans. We describe how the systems are connected and the optimal settings to record neurons and eye movements. To illustrate the utility of this method, we summarize results that were made possible by this setup. This data shows how using eye tracking in a memory-guided visual search task allowed us to describe a new class of neurons called target neurons, whose response was reflective of top-down attention to the current search target. Lastly, we discuss the significance and solutions to potential problems of this setup. Together, our protocol and results suggest that single-neuron recordings with simultaneous eye tracking in humans are an effective method to study human brain function. It provides a key missing link between animal neurophysiology and human cognitive neuroscience.

We describe a method to conduct single-neuron recordings with simultaneous eye tracking in humans. We demonstrate the utility of this method and illustrate how we used this approach to obtain neurons in the human medial temporal lobe that encode targets of a visual search.

Intracranial recordings from patients with intractable epilepsy provide a unique opportunity to study the activity of individual human neurons during ...

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 ...

Defining the Role Of Language in Infants' Object Categorization with Eye-tracking Paradigms

Assessing infant category learning is a challenging but vital aspect of studying infant cognition. By employing a familiarization-test paradigm, we straightforwardly measure infants&#8217; success in learning a novel category while relying only on their looking behavior. Moreover, the paradigm can directly measure the impact of different auditory signals on the infant categorization across a range of ages. For instance, we assessed how 2-year-olds learn categories in a variety of labeling environments: in our task, 2-year-olds successfully learned categories when all exemplars were labeled&#160;or the first two exemplars were labeled, but they failed to categorize when no exemplars were labeled or only the final two exemplars were labeled. To determine infants&#8217; success in such tasks, researchers can examine both the overall preference displayed by infants in each condition and infants&#8217; pattern of looking over the course of the test phase, using an eye-tracker to provide fine-grained time-course data. Thus, we present a powerful paradigm for identifying the role of language, or any auditory signal, in infants&#8217; object category learning.

Here we present a protocol for familiarization-test paradigms which provide a direct test of infant categorization and help to define the role of language in early category learning.

Assessing infant category learning is a challenging but vital aspect of studying infant cognition. By employing a familiarization-test paradigm, we ...

An Automated Method for Assessing Visual Acuity in Infants and Toddlers Using an Eye-Tracking System

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Gaze in Action: Head-mounted Eye Tracking of Children's Dynamic Visual Attention During Naturalistic Behavior

Simultaneous Eye Tracking and Single-Neuron Recordings in Human Epilepsy Patients

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

Defining the Role Of Language in Infants' Object Categorization with Eye-tracking Paradigms