We thank Bryton Hixson for setup assistance. This program was supported by the Basic Research Program, Environmental Quality and Installations (EQI; Dr. Elizabeth Ferguson, Technical Director), US Army Engineer Research and Development Center.

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All authors contributed to the experimental design, analyses and writing the paper. A.C.U. and C.M.W. setup and collected the data. The authors have nothing to disclose.

Visual cues are known to trigger an optomotor response in fish exposed to black and white gratings13 and there is increasing theoretical and empirical evidence that neighbor speed plays an influential role in governing the dynamical interactions observed in fish schools7,14,15,16,17. Contrasting hypotheses exist to explain how individuals in groups integrate neighbor movements, such as reacting proportionally to all discernible cues14, adopting a motion-threshold response17, or monitoring collision times18. A first step in testing these alternative hypotheses is validating their underlying assumptions. Here we demonstrated the utility of our protocol in identifying the role that a particular sensory feature can have on guiding directional decisions.
We isolated how individuals of a social fish species, the Golden Shiner, responded to changes in the relative speed of visual stimuli designed to mimic conspecifics in a school. Golden Shiner directional accuracy did improve with increases in the relative speed of the visual stimuli, but the functional relationship between these variables was only marginally disproportionate. The relationship between decision speed and stimulus speed, while significant, was highly variable and inconsistent. The results do demonstrate, however, that a speed difference found in images scattered across the field of view of these fish does play an important role in triggering a response and guiding their overt attention. Teasing apart how individuals select among the actions of specific neighbors could be probed with the current design by introducing conflicting directions in the stimuli.
In a recent experiment with Zebrafish, Danio rerio, we found no evidence of indecisiveness in solitary trials7, yet Golden Shiner in this demonstration displayed a greater reluctance to leave the holding area. The differences between these two species may be explained by their life history strategies and the relative strength of their social tendencies (or reliance). Zebrafish appear to display more variable social coherency than Golden Shiners (e.g., facultative vs. obligate schoolers3). It is likely that the stronger social coherency in Golden Shiner may have contributed to subjects showing higher levels of shyness, or hesitancy within the domain than their zebrafish counterparts.
The order of the steps is subtle yet critical in the protocol. The process of balancing the lights, the projector, and program filter can take more time than often anticipated for new domains. In this protocol, lessons learned have been included to reduce setup and light balance time, such as use of track lights that reflect off the wall (not on the domain), adjustable light controllers, and program-generated filters for the projector. Consider also that what may appear to be visually acceptable to the human eye will not be viewed by the camera and software the same way, thus your lighting conditions may require additional adjustments. Even slight changes in monitor angles will result in background gradient changes. Thus, detailed note taking and saving file settings will greatly reduce the likelihood of changes occurring during the experiment. Moving through the process from physical to filtering, as presented here, yields the fastest steps to success.
The use of a ST projector enables greater spatial flexibility over a monitor, but this approach creates an unwanted visual anomaly called a &#8220;hotspot&#8221;. A hotspot is a bright spot on the projection surface created by the proximity of the projector&#8217;s bulb. In the protocol, Section 4 was dedicated to the creation of background filters and checking for homogeneous lightning across the domain. The steps provided here will help users avoid, or minimize, the unwanted effects of the hotspot by modeling any unwanted gradient and using the model to reproduce an inverse gradient to counter the effects. Lastly, the ST projector model may vary, however, image adjustments (rotate, flip, front or rear screen projection) and keystone correction (&#177; 3-5 degrees) are useful features to ensure the desire image fits the domain and can be adjusted for distortion.
Over time, the experimental rooms were updated for ease by changes in the hardware (i.e., cameras, cabling, video cards, monitors). It is noteworthy to mention that hardware changes will likely result in additional start-up time to balance lighting and work through any potential program issues. Therefore, it is recommended that any hardware be dedicated to a system until completion of the desired experiments. Most challenges have been tied to performance differences between monitors, video cards and the cameras resulting sometimes in alteration of the programming code. Since the time of this work, new domains have been developed in which the inner test domain can be removed and switched for other test domains. We recommend this flexibility be considered when designing the experimental domains and support structures.
The current protocol allows investigators to isolate and manipulate visual features in a manner that both reflects the visual environment expected within a school, while also controlling for confounding factors that accompany exposure to real conspecifics (e.g., hunger, familiarity, aggression)7. In general, computer animation (CA) of virtual fish (i.e., silhouettes) is a practice that is becoming more common place due to its distinct advantages in stimulating behavioral responses19,20,21. CA allows one to customize visual cues (direction, speed, coherency, or morphology), while introducing a level of standardization and repeatability in the desired stimulus that exceeds what can be achieved when using live animals as the stimulant. The use of virtual reality in behavioral studies, on both animals22 and humans23, is also steadily increasing and promises to become a powerful empirical tool as the technology becomes more available and tractable. Taken together, these virtual approaches also replace and reduce the live animal requirements of animal ethics in science (e.g., IACUC, AAALAC, and ACURO)24, while concomitantly lowering laboratory costs and burdens.

Animals sense and interpret their habitat continuously to make informed decisions when interacting with others and navigating noisy surroundings. Individuals can enhance their situational awareness and decision making by integrating social information into their actions. Social information, however, largely stems from inference through unintended cues (i.e., sudden maneuvers to avoid a predator), which can be unreliable, rather than through direct signals that have evolved to communicate specific messages (e.g., the waggle dance in honey bees)1. Identifying how individuals rapidly assess the value of social cues, or any sensory information, can be a challenging task for investigators, particularly when individuals are traveling in groups. Vision plays an important role in governing social interactions2,3,4 and studies have inferred the interaction networks that may arise in fish schools based on each individual&#8217;s field of view5,6. Fish schools are dynamic systems, however, making it difficult to isolate individual responses to particular features, or neighbor behaviors, due to the inherent collinearities and confounding factors that arise from the interactions among group members. The purpose of this protocol is to complement current work by isolating how alternative visual features can influence the directional decisions of individuals traveling alone or within groups.
The benefit of the current protocol is to combine a manipulative experiment with computer visualization techniques to isolate the elementary visual features an individual may experience in nature. Specifically, the Y-maze (Figure 1) is used to collapse directional choice to a binary response and introduce computer animated images designed to mimic the swimming behaviors of virtual neighbors. These images are projected up from below the maze to mimic the silhouettes of conspecifics swimming beneath one or more subjects. The visual characteristics of these silhouettes, such as their morphology, speed, coherency, and swimming behavior are easily tailored to test alternative hypotheses7.
This paper demonstrates the utility of this approach by isolating how individuals of a model social fish species, the Golden Shiner (Notemigonus crysoleucas), respond to the relative speed of virtual neighbors. The protocol focus, here, is on whether the directional influence of virtual neighbors change with their speed and, if so, quantifying the form of the observed relationship. In particular, the directional cue is generated by having a fixed proportion of the silhouettes act as leaders and move ballistically towards one arm or another. The remaining silhouettes act as distractors by moving about at random to provide background noise that can be tuned by adjusting the leader/distractor ratio. The ratio of leaders to distractors captures the coherency of the directional cues and can be adjusted accordingly. Distractor silhouettes remain confined to the decision area (&#8220;DA&#8221;, Figure 1A) by having the silhouettes reflect off of the boundary. Leader silhouettes, however, are allowed to leave the DA region and enter their designated arm before slowly fading away once the silhouettes traversed 1/3 the length of the arm. As leaders leave the DA, new leader silhouettes take their place and retrace their exact path to ensure that the leader/distractor ratio remains constant in the DA throughout the experiment.
The use of virtual fish allows for the control of the visual sensory information, while monitoring the directional response of the subject, which may reveal novel features of social navigation, movement, or decision making in groups. The approach used here can be applied to a broad range of questions, such as effects of sublethal stress or predation on social interactions, by manipulating the computer animation to produce behavioral patterns of varying complexity.

<table>
	<tbody>
		<tr>
			<td>Black and white IP camera</td>
			<td>Noldus, Leesburg, VA, USA</td>
			<td></td>
			<td>https://www.noldus.com/</td>
		</tr>
		<tr>
			<td>Extruded aluminum</td>
			<td>80/20 Inc., Columbia City, IN, USA</td>
			<td>3030-S</td>
			<td>https://www.8020.net 3.00&#34; X 3.00&#34; Smooth T-Slotted Profile, Eight Open T-Slots</td>
		</tr>
		<tr>
			<td>Finfish Starter with Vpak, 1.5 mm extruded pellets</td>
			<td>Zeigler Bros. Inc., Gardners, PA, USA</td>
			<td></td>
			<td>http://www.zeiglerfeed.com/</td>
		</tr>
		<tr>
			<td>Golden shiners</td>
			<td>Saul Minnow Farm, AR, USA</td>
			<td></td>
			<td>http://saulminnow.com/</td>
		</tr>
		<tr>
			<td>ImageJ (v 1.52h) freeware</td>
			<td>National Institute for Health (NIH), USA</td>
			<td></td>
			<td>https://imagej.nih.gov/ij/</td>
		</tr>
		<tr>
			<td>LED track lighting</td>
			<td>Lithonia Lightening, Conyers, GA, USA</td>
			<td>BR20MW-M4</td>
			<td>https://lithonia.acuitybrands.com/residential-track</td>
		</tr>
		<tr>
			<td>Oracle 651 white cut vinyl</td>
			<td>651Vinyl, Louisville, KY, USA</td>
			<td>651-010M-12:5ft</td>
			<td>http://www.651vinyl.com. Can order various sizes.</td>
		</tr>
		<tr>
			<td>PowerLite 570 overhead projector</td>
			<td>Epson, Long Beach CA, USA</td>
			<td>V11H605020</td>
			<td>https://epson.com/For-Work/Projectors/Classroom/PowerLite-570-XGA-3LCD-Projector/p/V11H605020</td>
		</tr>
		<tr>
			<td>Processing (v 3) freeware</td>
			<td>Processing Foundation</td>
			<td></td>
			<td>https://processing.org/</td>
		</tr>
		<tr>
			<td>R (3.5.1) freeware</td>
			<td>The R Project for Statistical Computing</td>
			<td></td>
			<td>https://www.r-project.org/</td>
		</tr>
		<tr>
			<td>Ultra-white 360 theater screen</td>
			<td>Alternative Screen Solutions, Clinton, MI, USA</td>
			<td>1950</td>
			<td>https://www.gooscreen.com. Must call for special cut size</td>
		</tr>
		<tr>
			<td>Z-Hab system</td>
			<td>Pentair Aquatic Ecosystems, Apopka, FL, USA</td>
			<td></td>
			<td>https://pentairaes.com/. Call for details and sizing.</td>
		</tr>
	</tbody>
</table>

integrating visual psychophysical assays within a y-maze to isolate the role that visual features play in navigational decisions

Collective animal behavior arises from individual motivations and social interactions that are critical for individual fitness. Fish have long inspired investigations into collective motion, specifically, their ability to integrate environmental and social information across ecological contexts. This demonstration illustrates techniques used for quantifying behavioral responses of fish, in this case, Golden Shiner (Notemigonus crysoleucas), to visual stimuli using computer visualization and digital image analysis. Recent advancements in computer visualization allow for empirical testing in the lab where visual features can be controlled and finely manipulated to isolate the mechanisms of social interactions. The purpose of this method is to isolate visual features that can influence the directional decisions of the individual, whether solitary or with groups. This protocol provides specifics on the physical Y-maze domain, recording equipment, settings and calibrations of the projector and animation, experimental steps and data analyses. These techniques demonstrate that computer animation can elicit biologically-meaningful responses. Moreover, the techniques are easily adaptable to test alternative hypotheses, domains, and species for a broad range of experimental applications. The use of virtual stimuli allows for the reduction and replacement of the number of live animals required, and consequently reduces laboratory overhead.
This demonstration tests the hypothesis that small relative differences in the movement speeds (2 body lengths per second) of virtual conspecifics will improve the speed and accuracy with which shiners follow the directional cues provided by the virtual silhouettes. Results show that shiners directional decisions are significantly affected by increases in the speed of the visual cues, even in the presence of background noise (67% image coherency). In the absence of any motion cues, subjects chose their directions at random. The relationship between decision speed and cue speed was variable and increases in cue speed had a modestly disproportionate influence on directional accuracy.

Hypothesis and design 
To demonstrate the utility of this experimental system we tested the hypothesis that the accuracy with which Golden Shiner follow a visual cue will improve with the speed of that cue. Wild type Golden Shiner were used (N = 16, body lengths, BL, and wet weights, WW, were 63.4 &#177; 3.5 mm and 1.8 &#177; 0.3 g, respectfully). The coherency of the visual stimuli (leader/distractor ratio) were fixed at 0.67, while we manipulated the speed at which our motion cues (i.e., the leaders) moved with respect to their distractors. Speed levels of the leader silhouettes that provide the directional cues ranged from 0-10 BL/s (in increments of 2), which spans the range of speeds typically considered to reflect sustained, prolonged, or burst swimming modes of activity in fish12. At the control level, 0, the leader silhouettes were oriented towards a destination arm among the randomly oriented distractors, but none of the silhouettes moved. The destination arm was chosen at random for each trial by the program. Distance units are in body length, which was defined by the mean standard length of our subjects, and time is in seconds. The current representative analysis focuses on measuring primary response variables (decision speed and accuracy), yet the design of the experiment also enables investigators to extract added information by tracking subject movements and analyzing their kinematics.
Our fish subjects were housed following section 6 of the protocol. Each subject was exposed to one level of the treatment per day. We randomized both within subject treatment level (cue speed) across days and the order in which subjects were tested on each day. Linear and generalized linear mixed effects models (LMM and GLMM, respectively) were used to test the effects of leader silhouette speed on the speed and accuracy with which subjects followed the visual stimuli. Subject id was included as the random effect in both models.
Data and findings 
In the absence of any motion cues Golden Shiner acted as expected and chose their direction at random (stimulus speed = 0, binomial test, nLeft = 33, nRight = 40, = 0.45, P = 0.483). While most subjects showed no signs of stressful behavior within the domain and made a decisive decision within the allotted time (5 min), 22% of the subjects showed a reluctance to leave the holding area or enter the decision area. Data from these indecisive fish were not included in the analysis. The remaining 78% of our subjects showed a significant improvement in the accuracy with which they followed the directional stimuli as the speed of those stimuli increased (GLMM, z = 1.937, P = 0.053). Figure 5A shows the nature of this relationship, where we find a 1.2-fold increase in directional accuracy for each increase in stimulus speed level. This relationship is only modestly disproportionate and is not, by itself, suggestive of a threshold response to changes in cue speed. Increases in stimulus speed also led to a significant increase in decision speed (LMM, F1,56 = 4.774, P = 0.033). However, as evident in Figure 5B the trend in decision speed was inconsistent and highly variable across stimulus speed levels. What is apparent in these decision speed data is that it took subjects, on average, anywhere from 5-20x longer to make their decision when the stimuli were moving than when they were not (decision speeds of 4.6 &#177; 2.3 s and 81.4 &#177; 74.7 s for stimulus speeds of 0 and 8, respectively, &#177; standard deviation, SD). Indeed, without the control level we found no significant change in decision speed as a function of stimulus speed.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/59281/59281fig1.jpg" /> 
Figure 1. Y-Maze domain. A. Image of the Y-maze apparatus for decision-making test. Annotations represent the following: Holding Area (HA, green), Decision Area (DA, blue), Left Decision Arm (LDA), and Right Decision Arm (RDA). B. Image of the Y-maze and room with overhead adjustable track lighting and GigE camera placement (only one of the four overheads lights strips are visible). C. Image of the Y-maze (side-view) including the projector placement which is locked by the sliding carriage to eliminate movements during, or between, trials. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/59281/59281fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/59281/59281fig2.jpg" /> 
Figure 2. Background and stimulus calibration. A. Image of the illuminated Y-maze with a uniform background color and a pixel intensity transect (green line) between the holding area and the Decision Area, DA (mean pixel intensity 112 &#177; 1278). The light gradient generated by the projector&#8217;s bulb (hotspot) is clearly visible. B. Image showing the alignment of the projections with the DA. C. Image of the maze with the filtered background and a solitary silhouette projected in the center of the DA for calibration (size, speed). The addition of the counter gradient background in (C) results in a darker background (mean pixel intensity 143.1 &#177; 5.5) and far less spatial variability (coefficient of variation drops from 11.4 (A.) to 0.03 (C.). <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/59281/59281fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/59281/59281fig3.jpg" /> 
Figure 3. Schematic of the general flow of operations in the visualization program used in the experiments. For additional procedural details see7. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/59281/59281fig3large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/59281/59281fig4.jpg" /> 
Figure 4. Experimental trial with both real and virtual fish silhouettes. A. Image a (live) Golden Shiner leaving the holding area (green circle). B. Image of a (live) Golden Shiner in the decision area (green circle) among the virtual fish silhouettes. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/59281/59281fig4large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 5" class="xfigimg" src="/files/ftp_upload/59281/59281fig5.jpg" /> 
Figure 5. Accuracy and speed of directional responses to changes in the relative speed of motion cues. A. Graph of the fish decision accuracy with which Golden Shiner followed the &#8216;leader&#8217; silhouettes plotted against the stimulus speed (BL/s). B. Graph of the fish decision speed plotted against the stimulus speed (BL/s). Data are means &#177; standard errors, SE. Groups of 15 virtual silhouettes were randomly distributed throughout the decision zone with a 67% coherency level (10 of the 15 silhouettes acted as Leaders, the remaining 5 silhouettes acted as distractors) and we varied the speed of the leaders from 0-10 BL/s. Distractor speeds remained fixed at 1 BL/s at all speed levels, except the control in which none of the silhouettes moved. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/59281/59281fig5large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

Watch this Scientific Journal Video about Integrating Visual Psychophysical Assays within a Y-Maze to Isolate the Role that Visual Features Play in Navigational Decisions at JoVE.com

Integrating Visual Psychophysical Assays within a Y-Maze to Isolate the Role that Visual Features Play in Navigational Decisions

Here, we present a protocol to demonstrate a behavioral assay that quantifies how alternative visual features, such as motion cues, influence directional decisions in fish. Representative data are presented on the speed and accuracy where Golden Shiner (Notemigonus crysoleucas) follow virtual fish movements.

Collective animal behavior arises from individual motivations and social interactions that are critical for individual fitness. Fish have long inspired ...

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6.0K Views.  US Army Engineer Research and Development Center. Here, we present a protocol to demonstrate a behavioral assay that quantifies how alternative visual features, such as motion cues, influence directional decisions in fish. Representative data are presented on the speed and accuracy where Golden Shiner (Notemigonus crysoleucas) follow virtual fish movements.

Video: Integrating Visual Psychophysical Assays within a Y-Maze to Isolate the Role that Visual Features Play in Navigational Decisions

Methods to Explore the Influence of Top-down Visual Processes on Motor Behavior

Kinesthetic awareness is important to successfully navigate the environment. When we interact with our daily surroundings, some aspects of movement are deliberately planned, while others spontaneously occur below conscious awareness. The deliberate component of this dichotomy has been studied extensively in several contexts, while the spontaneous component remains largely under-explored. Moreover, how perceptual processes modulate these movement classes is still unclear. In particular, a currently debated issue is whether the visuomotor system is governed by the spatial percept produced by a visual illusion or whether it is not affected by the illusion and is governed instead by the veridical percept. Bistable percepts such as 3D depth inversion illusions (DIIs) provide an excellent context to study such interactions and balance, particularly when used in combination with reach-to-grasp movements. In this study, a methodology is developed that uses a DII to clarify the role of top-down processes on motor action, particularly exploring how reaches toward a target on a DII are affected in both deliberate and spontaneous movement domains.

It is unclear how top-down signals from the ventral visual stream affect movement. We developed a paradigm to test motor behavior towards a target on a 3D depth inversion illusion. Significant differences are reported in both deliberate, goal-directed movements and automatic actions under illusory and veridical viewing conditions.

Kinesthetic awareness is important to successfully navigate the environment. When we interact with our daily surroundings, some aspects of movement are ...

Practical Methodology of Cognitive Tasks Within a Navigational Assessment

This paper describes an approach for measuring navigation accuracy relative to cognitive skills. The methodology behind the assessment will thus be clearly outlined in a step-by-step manner. Navigational skills are important when trying to find symbols within a speech-generating device (SGD) that has a dynamic screen and taxonomical organization. The following skills have been found to impact children&#8217;s ability to find symbols when navigating within the levels of an SGD: sustained attention, categorization, cognitive flexibility, and fluid reasoning1,2. According to past studies, working memory was not correlated with navigation1,2.
The materials needed for this method include a computerized tablet, an augmentative and alternative communication application, a booklet of symbols, and the Leiter International Performance Scale-Revised (Leiter-R)3. This method has been used in two previous studies. Robillard, Mayer-Crittenden, Roy-Charland, Minor-Corriveau and B&#233;langer1 assessed typically developing children, while Rondeau, Robillard and Roy-Charland2 assessed children and adolescents with a diagnosis of Autism Spectrum Disorder. The direct observation of this method will facilitate the replication of this study for researchers. It will also help clinicians that work with children who have complex communication needs to determine the children&#8217;s ability to navigate an SGD with taxonomical categorization.

Children who have complex communication needs can benefit from the use of a speech-generating device (SGD). Cognitive skills were identified as having an impact on the ability to navigate between levels of SGDs. This protocol describes the steps needed for Speech-language Pathologists to assess cognitive skills and navigational abilities.

This paper describes an approach for measuring navigation accuracy relative to cognitive skills. The methodology behind the assessment will thus be ...

Methods to Test Visual Attention Online

Online data collection methods have particular appeal to behavioral scientists because they offer the promise of much larger and much more representative data samples than can typically be collected on college campuses. However, before such methods can be widely adopted, a number of technological challenges must be overcome &#8211; in particular in experiments where tight control over stimulus properties is necessary. Here we present methods for collecting performance data on two tests of visual attention. Both tests require control over the visual angle of the stimuli (which in turn requires knowledge of the viewing distance, monitor size, screen resolution, etc.) and the timing of the stimuli (as the tests involve either briefly flashed stimuli or stimuli that move at specific rates). Data collected on these tests from over 1,700 online participants were consistent with data collected in laboratory-based versions of the exact same tests. These results suggest that with proper care, timing/stimulus size dependent tasks can be deployed in web-based settings.

To replicate laboratory settings, online data collection methods for visual tasks require tight control over stimulus presentation. We outline methods for the use of a web application to collect performance data on two tests of visual attention.

Online data collection methods have particular appeal to behavioral scientists because they offer the promise of much larger and much more representative ...

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 ...

Visualizing Visual Adaptation

Many techniques have been developed to visualize how an image would appear to an individual with a different visual sensitivity: e.g., because of optical or age differences, or a color deficiency or disease. This protocol describes a technique for incorporating sensory adaptation into the simulations. The protocol is illustrated with the example of color vision, but is generally applicable to any form of visual adaptation. The protocol uses a simple model of human color vision based on standard and plausible assumptions about the retinal and cortical mechanisms encoding color and how these adjust their sensitivity to both the average color and range of color in the prevailing stimulus. The gains of the mechanisms are adapted so that their mean response under one context is equated for a different context. The simulations help reveal the theoretical limits of adaptation and generate &#34;adapted images&#34; that are optimally matched to a specific environment or observer. They also provide a common metric for exploring the effects of adaptation within different observers or different environments. Characterizing visual perception and performance with these images provides a novel tool for studying the functions and consequences of long-term adaptation in vision or other sensory systems.

This article describes a novel method for simulating and studying adaptation in the visual system.

Many techniques have been developed to visualize how an image would appear to an individual with a different visual sensitivity: e.g., because of optical ...

Psychophysical Tracking Method to Measure Taste Preferences in Children and Adults

The Monell two-series, forced-choice, paired-comparison tracking method provides a reliable measure of sweet taste preferences from childhood to adulthood. The method, which is identical for children, adolescents, and adults, is of short duration (&#60; 15 min), does not rely on sustained attention or place demands on memory (which would yield spurious age differences), and minimizes the impact of language development, making this method amenable to the cognitive limitations of pediatric populations. In this whole-mouth tasting method, subjects are asked to taste (without swallowing) pairs of solutions of different sucrose concentrations and to point to the solution they prefer. Each subsequent pair contains the participant&#39;s preceding preferred concentration and an adjacent stimulus concentration. The procedure continues until the subject chooses either a given concentration of sucrose when paired with both a higher and a lower concentration, or the highest or lowest concentration two consecutive times. Subjects are prevented from reaching response criteria on the basis of first or second position bias by the two-series design of the method, which counterbalances the order of solution presentation within each pair between the series (the weaker concentration is presented first in Series 1, second in Series 2). The geometric mean of the two sucrose concentrations chosen in Series 1 and 2 is an estimate of the participant&#39;s most preferred level of sucrose. Sucrose preference as determined with this laboratory-based measure has been shown to be associated with preference for sugars in foods and beverages and with taste receptor genotype, family history of alcoholism, and race/ethnicity, as well as depressive symptomatology among pediatric populations. The method has real-world relevance and has been applied to determine most preferred level of other tastes (e.g., salt), making it a valuable psychophysical tool.

Sweet taste has powerful hedonic appeal among people of all ages, particularly children. Described herein is a reliable and valid method that can be used to determine the level of sweetness most preferred, making it a valuable psychophysical tool for scientists.

The Monell two-series, forced-choice, paired-comparison tracking method provides a reliable measure of sweet taste preferences from childhood to ...

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 ...

Visual Classical Conditioning in Wood Ants

Several species of insects have become model systems for studying learning and memory formation. Although many studies focus on freely moving animals, studies implementing classical conditioning paradigms with harnessed insects have been important for investigating the exact cues that individuals learn and the neural mechanisms underlying learning and memory formation. Here we present a protocol for evoking visual associative learning in wood ants through classical conditioning. In this paradigm, ants are harnessed and presented with a visual cue (a blue cardboard), the conditional stimulus (CS), paired with an appetitive sugar reward, the unconditional stimulus (US). Ants perform a Maxilla-Labium Extension Reflex (MaLER), the unconditional response (UR), which can be used as a readout for learning. Training consists of 10 trials, separated by a 5-minute intertrial interval (ITI). Ants are also tested for memory retention 10 minutes or 1 hour after training. This protocol has the potential to allow researchers to analyze, in a precise and controlled manner, the details of visual memory formation and the neural basis of learning and memory formation in wood ants.

We present a protocol for the classical conditioning of harnessed ants that permits researchers to study visual learning and memory formation at a level of analysis not possible with freely moving individuals.

Several species of insects have become model systems for studying learning and memory formation. Although many studies focus on freely moving animals, ...

Using the Visual World Paradigm to Study Sentence Comprehension in Mandarin-Speaking Children with Autism

Sentence comprehension relies on the ability to rapidly integrate different types of linguistic and non-linguistic information. However, there is currently a paucity of research exploring how preschool children with autism understand sentences using different types of cues. The mechanisms underlying sentence comprehension remains largely unclear. The present study presents a protocol to examine the sentence comprehension abilities of preschool children with autism. More specifically, a visual world paradigm of eye-tracking is used to explore the moment-to-moment sentence comprehension in the children. The paradigm has multiple advantages. First, it is sensitive to the time course of sentence comprehension and thus can provide rich information about how sentence comprehension unfolds over time. Second, it requires minimal task and communication demands, so it is ideal for testing children with autism. To further minimize the computational burden of children, the present study measures eye movements that arise as automatic responses to linguistic input rather than measuring eye movements that accompany conscious responses to spoken instructions.

We present a protocol to examine the use of morphological cues during real-time sentence comprehension by children with autism.

Sentence comprehension relies on the ability to rapidly integrate different types of linguistic and non-linguistic information. However, there is ...

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 ...