This work was supported by the National Institute of Deafness and Other Communication Disorders (NIDCD), National Institutes of Health (NIH) [grant number R01 DC011287] and NIH postdoctoral training grant (T32-DC00014). The content is solely the responsibility of the authors and does not necessarily represent the official views of NIDCD or NIH. The funding agencies had no role in the design and conduct of the study; in the collection, analysis, and interpretation of the data; or in the preparation or contents of the manuscript.

This method has been approved by the Office of Regulatory Affairs at the University of Pennsylvania. For the research studies described herein, informed consent was obtained from each adult and informed assent from each child seven years of age or older.
1. General Considerations
<ol>
	<li>Conduct the preference test in a comfortable, private room that ideally has a sink for subjects to expectorate solutions during testing. If a sink is not available, give subjects a cup into which to expectorate.</li>
</ol>
2. Test Materials
<ol>
	<li>Obtain 1-L volumetric flasks, 1-L amber glass bottles, and 100 ml amber glass bottles for the preparation, storage, and dispensing of solutions. For testing, obtain the following materials: 30 ml disposable medicine cups for solutions; drinking cups containing water for rinsing in between trials; a stopwatch to monitor inter-pair and inter-series intervals; distilled water for solution preparation and for rinsing; a cup for expectoration (if the testing room does not contain a sink); a sheet of paper labeled with the numbers 1 and 2 representing the order of tasting; and a tracking grid (Figure 1) for recording data.</li>
</ol>
<img alt="Figure 1" src="/files/ftp_upload/54163/54163fig1.jpg" /> 
Figure 1. Tracking grids for recording sucrose preference. The solution presented first is underlined in each grid. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54163/54163fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<ol start="2">
	<li>Clean and sterilize all bottles in an autoclave, and label each with the date and the stimulus label: A, B, C, D, E. Weigh the appropriate amount of sucrose to make solutions A through E (Table 1).</li>
	<li>Making one solution at a time, place the appropriate grams of sucrose (Table 1) in 1 L volumetric flask and fill to the line on the flask with distilled water. Mix to dissolve the sucrose. Once sucrose is dissolved, transfer the solution to the appropriately labeled 1 L amber glass bottle.</li>
	<li>Store the solution-containing bottles in the refrigerator (4 &#176;C) for a maximum of one week. Repeat step 2.3 to make the remaining four solutions. Solutions will be enough to test approximately 25-30 subjects.</li>
	<li>Construct tracking grid to record subject data, using template found in Figure 1. Label each grid with the Series number (1 or 2) and the concentrations of the sucrose solutions, and include space to record the start and end times of each series. Include a column on each grid to record notes as necessary during the test.</li>
</ol>
3. Subject and Testing Preparation
<ol>
	<li>Instruct adults to abstain from eating or drinking and instruct parents to not give child participants anything to eat or drink for at least 1 hr before testing.</li>
	<li>Two hr before testing, remove solutions from the refrigerator, transfer approximately 100 ml of each to the appropriately labeled 100 ml amber glass bottles, and allow the solutions to equilibrate to RT.</li>
	<li>Seat the subject at a table in front of the sheet of paper labeled with the numbers 1 and 2, and allow the subject to acclimate to the testing room and the tester for at least 10 min.</li>
</ol>
4. Psychophysical Method
Note: The preference test is a two-series, forced-choice, paired comparison tracking technique in which subjects are asked to taste (without swallowing) pairs of solutions of different concentrations and to point to the solution they prefer. Below are the introductory verbal instructions given to pediatric and adult subjects at the time of testing, followed by investigator instructions on how to conduct the preference test.
<ol>
	<li>Verbal Instructions to Subjects
	<ol>
		<li>Pediatric Subjects
		<ol>
			<li>Show the cups to the subject and say: &#34;We&#39;re going to play a game with things to taste. Here are two cups. You will taste what&#39;s inside the first cup, swish it around your mouth, but don&#39;t swallow, and I will tell you when to spit it out in the sink (or cup). You will then rinse your mouth with water, and then taste what&#39;s inside the second cup. I will tell you when to spit it out. Then I want you to point to which one you like better-the first one or the second one. You will then rinse your mouth two times with water, and we will do this again. There is no right or wrong answer; we want to know which one you like better.&#34;</li>
		</ol>
		</li>
		<li>Adolescents and Adults
		<ol>
			<li>Show the cups to the subject and say: &#34;We&#39;re going to give you solutions to taste. Here are two cups. You will taste what&#39;s inside the first cup, swish it around your mouth, but don&#39;t swallow, and I will tell you when to spit it out in the sink (or cup). You will then rinse your mouth with water, and then taste what&#39;s inside the second cup. I will tell you when to spit it out. Then I want you to point to which one you like better-the first one or the second one. You will then rinse your mouth two times with water, and we will do this again. There are no right or wrong answers; we want to know which one you like better.&#34;</li>
		</ol>
		</li>
	</ol>
	</li>
	<li>Investigator Instructions
	<ol>
		<li>For Series 1, begin by placing two cups, respectively containing 5 ml of solution B and 5 ml of solution D on a sheet of paper labeled with the numbers 1 and 2 in front of the subject: Place solution B on number 1 to be tasted first. Place solution D on number 2 and have the participant taste second. In Series 1, always place the weaker (lower) concentration solution of the pair in the number 1 position. Using the grid in Figure 1, underline the concentration that is presented first (solution B).</li>
		<li>Instruct the subject to taste the solution in position 1 by swishing; after 5 sec instruct the subject to expectorate, to rinse his or her mouth with water, and to expectorate again.</li>
		<li>Instruct the subject to taste the solution in position 2 by swishing, and to expectorate after 5 sec.</li>
		<li>Ask the subject to point to the solution the subject likes better. If the subject says they like both, instruct the subject to again point to the one they like better. Circle the X on the grid (Figure 1) that corresponds to the subject&#39;s preferred concentration.</li>
		<li>Instruct the subject to rinse his or her mouth twice with water and to expectorate. Use the timer to wait 1 min before presenting the next pair of solutions.</li>
		<li>For the second comparison of solutions in Series 1, pair the preferred concentration from the first comparison with the lower adjacent concentration. For example, if the subject prefers solution D to solution B in the first pair, then present the second pair consisting of solutions C and D. Place solution C (the lower concentration) in position 1 and solution D in position 2. Indicate which solutions are being presented by marking X&#39;s on the grid and underline the X that corresponds to the solution presented in position 1 (in this case Solution C).</li>
		<li>Repeat this process until the subject chooses the same concentration when presented with both a lower and higher adjacent concentration (e.g., if the subject chooses C when paired both with B and with D), or when the subject chooses either the lowest (A) or the highest concentration (E) twice consecutively.</li>
		<li>Record each subject&#39;s preferred concentration from Series 1 on the grid, and wait 3 min before beginning Series 2.</li>
		<li>For Series 2, pour 5 ml of each of solutions B and D into disposable cups, and place solution D on number 1 and solution B on number 2 in front of the subject. In Series 2, the stronger (higher) concentration solution of the pair is always placed in the number 1 position. Using the grid, underline the concentration that is presented first (D).</li>
		<li>Instruct the subject to taste and expectorate the solutions following the protocol used for Series 1 as outlined in steps 4.2.2-4.2.8.</li>
		<li>For the second comparison of solutions in Series 2, pair the preferred concentration from the first comparison with the higher adjacent concentration. For example, if the subject prefers solution D to solution B in the first pair, present solutions E and D in the second pair, placing solution E (the higher concentration) in position 1.</li>
		<li>Repeat this process until the subject chooses the same concentration when presented with both a lower and higher adjacent concentration, or when the subject chooses either the lowest or the highest concentration twice consecutively.</li>
		<li>Record the subject&#39;s preferred concentration from Series 2 by circling it on the grid.</li>
		<li>Determine the subject&#39;s preferred level of sucrose by calculating the geometric mean of the concentrations chosen in the two series (the square root of the product of the two concentrations): 
		Geometric Mean = &#8730; (series 1 preference) x (series 2 preference)</li>
	</ol>
	</li>
</ol>

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L., Anzman-Frasca, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Learning+to+prefer+the+familiar+in+obesogenic+environments.">Learning to prefer the familiar in obesogenic environments.</a> Nestle Nutr Workshop Ser Pediatr Program. 68, 187-196 (2011).</li><li>Drewnowski, A., Rehm, C. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Consumption+of+added+sugars+among+US+children+and+adults+by+food+purchase+location+and+food+source.">Consumption of added sugars among US children and adults by food purchase location and food source.</a> Am J Clin Nutr. 100 (3), 901-907 (2014).</li><li>Department of Agriculture and U.S. Department of Health and Human Services. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Dietary Guidelines for Americans, 2010. 7th edn. , (2010).</li><li>Chambers, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Commentary:+conducting+sensory+research+in+children.">Commentary: conducting sensory research in children.</a> J Sens Stud. 20 (1), 90-92 (2005).</li><li>Laing, D. G., 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=Tests+for+screening+olfactory+and+gustatory+function+in+school-age+children.">Tests for screening olfactory and gustatory function in school-age children.</a> Otolaryngol Head Neck Surg. 139 (1), 74-82 (2008).</li><li>Mennella, J. A., Beauchamp, G. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optimizing+oral+medications+for+children.">Optimizing oral medications for children.</a> Clin Ther. 30 (11), 2120-2132 (2008).</li><li>Chen, A. W., Resurreccion, A. 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A., Lukasewycz, L. D., Griffith, J. W., Beauchamp, G. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evaluation+of+the+Monell+forced-choice,+paired-comparison+tracking+procedure+for+determining+sweet+taste+preferences+across+the+lifespan.">Evaluation of the Monell forced-choice, paired-comparison tracking procedure for determining sweet taste preferences across the lifespan.</a> Chem Senses. 36 (4), 345-355 (2011).</li><li>Coldwell, S. E., 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=Gustation+assessment+using+the+NIH+Toolbox.">Gustation assessment using the NIH Toolbox.</a> Neurology. 80 (11), 20-24 (2013).</li><li>Beauchamp, G. K., Cowart, B. 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R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genetic+and+environmental+determinants+of+bitter+perception+and+sweet+preferences.">Genetic and environmental determinants of bitter perception and sweet preferences.</a> Pediatrics. 115 (2), 216-222 (2005).</li><li>Mennella, J. A., Pepino, M. Y., Lehmann-Castor, S. M., Yourshaw, L. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sweet+preferences+and+analgesia+during+childhood:+effects+of+family+history+of+alcoholism+and+depression.">Sweet preferences and analgesia during childhood: effects of family history of alcoholism and depression.</a> Addiction. 105 (4), 666-675 (2010).</li><li>Mennella, J. A., Finkbeiner, S., Lipchock, S. V., Hwang, L. D., Reed, D. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preferences+for+salty+and+sweet+tastes+are+elevated+and+related+to+each+other+during+childhood.">Preferences for salty and sweet tastes are elevated and related to each other during childhood.</a> PLoS One. 9 (3), e92201 (2014).</li><li>Kim, J. Y., Prescott, J., Kim, K. O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Patterns+of+sweet+liking+in+sucrose+solutions+and+beverages.">Patterns of sweet liking in sucrose solutions and beverages.</a> Food Qual Prefer. 36, 96-103 (2014).</li><li>Pepino, M. Y., Mennella, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Factors+contributing+to+individual+differences+in+sucrose+preference.">Factors contributing to individual differences in sucrose preference.</a> Chem Senses. 30, 319-320 (2005).</li><li>Mennella, J. A., Finkbeiner, S., Reed, D. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+proof+is+in+the+pudding:+children+prefer+lower+fat+but+higher+sugar+than+do+mothers.">The proof is in the pudding: children prefer lower fat but higher sugar than do mothers.</a> Int J Obes (Lond). 36 (10), 1285-1291 (2012).</li><li>Pepino, M. Y., Mennella, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+cigarette+smoking+and+family+history+of+alcoholism+on+sweet+taste+perception+and+food+cravings+in+women.">Effects of cigarette smoking and family history of alcoholism on sweet taste perception and food cravings in women.</a> Alcohol Clin Exp Res. 31 (11), 1891-1899 (2007).</li><li>Schmidt, H. J., Beauchamp, G. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Adult-like+odor+preferences+and+aversions+in+three-year-old+children.">Adult-like odor preferences and aversions in three-year-old children.</a> Child Dev. 59 (4), 1136-1143 (1988).</li><li>Temple, E. C., Hutchinson, I., Laing, D. G., Jinks, A. 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The authors declare they have no competing financial interests.

The Monell two-series, forced-choice, paired-comparison tracking technique detailed here has been consistently used to determine sweet taste preference among nearly 2,000 racially and ethnically diverse subjects as young as 5 years of age. The preference test, which for children is embedded within the context of a game, is sensitive to the cognitive limitations of children and is a much-needed method to fill the gap in age-appropriate psychophysical research methods for pediatric populations. If completed as described, with special attention paid to enforcing the 5-sec tasting protocol, subjects thoroughly rinsing their mouths with water both within and between solution pairs, and strict monitoring of inter-pair and inter-series intervals, the method is safe, reliable, and quick; results are easily interpreted and provide insight into an important dimension of sweet taste perception. In addition, because children are not required to verbalize their response, instructions for the method could easily be translated into other languages to allow for cross-cultural studies.
Findings from use of the described method have contributed extensively to the current understanding of the relationship between sweet preference and a number of genetic and environmental factors. Data collected over nearly a decade from separate groups of subjects have consistently revealed that, as a group, children most prefer a higher concentration of sucrose than do adults, an age-related difference that has been remarkably stable over the past decade28. Use of the method has also revealed sources of individual differences in sweet taste preference among both children and adults, including variation in taste receptor genes19,23, race/ethnicity15,23, family history of alcoholism20,25, and depressive symptomatology20.
The method has real-world relevance and can be used with children five years of age and perhaps even younger18; however, like any other psychophysical method, there will likely be limitations in its use with younger children. Because the method does not require verbal responses, the instructions can easily be translated to other languages, making it a valuable psychophysical tool for scientists worldwide. The method has successfully been used to determine children&#39;s and adults&#39; most preferred level of salt17,18,21, and has the potential to be adapted to determine preferences for stimuli of varying hedonic qualities, adding to our growing understanding of taste response from childhood to adulthood. Finally, future applications could use the method to determine whether changes in the intake of nutritive or non-nutritive sugars might shift the individual&#39;s most preferred level of sucrose, as has been demonstrated with alterations in most preferred level of salt following changes in dietary salt intake29,30.

The sense of taste controls one of the most important decisions we make: whether to eat something or not. From birth, humans show a strong liking for sweet taste1-it attracts the newborn to mother&#39;s milk and signals the presence of calories from nutrient-dense foods (e.g., fruits)2. Although this inborn trait confers an advantage for survival in an environment of scarcity, an individual&#39;s liking for sweet coupled with a food environment that supplies sugar in abundance has resulted in overconsumption of sweetened foods3. Current estimates suggest that 13.1-17.5% of children&#39;s and 11.2-14.5% of adults&#39; total energy intake is derived from added sugars4; in both cases, levels are well above national and international dietary recommendations5,6.
Despite the importance of taste in determining food choice and intake, and the association between diet and health, methodologies to accurately assess taste hedonics are limited, particularly for use with pediatric populations7-9. One of the methods most commonly used with children is hedonic category scaling10-12, which involves choosing a response from a series of discrete alternatives that signify increasing preference. These alternatives are often depicted with smiley faces10 or with verbal descriptors ranging from &#34;super bad&#34; to &#34;super good&#34;13, and are useful for determining whether a child likes the taste of a stimulus or not. Ranking procedures, in which a subject is required to order several choices by how well they are liked (e.g., from most to least liked), are also frequently used and are intended to convey information on relative liking of stimuli13,14. Although both methods provide valuable information on two separate dimensions of hedonic response, neither directly assesses taste preference, specifically the concentration of a stimulus perceived to be of optimal palatability. The method described herein was specifically developed to determine an individual&#39;s most preferred level of a tastant through direct comparisons of pairs of stimuli of varying concentrations, bypassing the need to infer preference from ratings of stimuli evaluated individually in a sequential monadic manner, as is often practiced in psychophysical testing.
Here, we detail the protocol for the Monell two-series, forced-choice, paired-comparison tracking technique for determining sweet taste preferences15,16. The method was first developed for measuring salt preference17,18. It was later modified for measuring sucrose preference19,20, tested for measures of both reliability and validity15, and selected for the National Institutes of Health Toolbox Assessment for Neurological and Behavioral Function as the method of choice to assess children&#39;s sweet taste preference for clinical, epidemiological, and longitudinal studies16. The method, which typically takes no more than 15 min to complete, has been used to measure the most preferred level of sucrose among hundreds of children, adolescents, and adults15,19-25. In a study of 949 subjects, only 5% of the 356 children tested were unable to complete both series of the sweet preference test due to unfocused behavior or failure to understand the task15, highlighting the appropriateness of the method for pediatric populations.
In brief, following a 1-hr fast, consenting subjects are presented with pairs of sucrose solutions of varying concentrations (3-36%) in a two-series test, with the lower concentration presented in the first position in each pair in the first series. Subjects taste the pair of solutions and are instructed to point to the solution they prefer. Subsequent pairs of solutions are presented based on the subject&#39;s preferred concentration in the previous pair. The test continues until the subject selects the same sucrose concentration twice relative to both a lower and a higher concentration, or until the subject selects the lowest (3%) or highest (36%) concentration twice consecutively. The protocol is then repeated in reverse order, with higher concentrations presented in the first position in each pair. On average, the method requires 7 presentations of solution pairs16.
The described method is particularly effective for use with children because it accounts for several methodological concerns often overlooked in other psychophysical tests: (1) the method is short in duration and does not require a sustained attention span; (2) the two-series protocol in which solution concentrations are counterbalanced between the series controls for position bias; (3) the forced-choice procedure circumvents children&#39;s inclination to answer questions in the affirmative26; (4) use of a whole-mouth instead of a regional-tasting protocol accounts for age-related differences in the growth and size of the tongue27; and (5) instructing children to point to their most preferred concentration of sucrose addresses potential cognitive limitations by eliminating the need for a verbal response19.
Since its development, the Monell two-series, forced-choice, paired-comparison tracking technique has revealed consistent differences in sweet taste preference as a function of age15,28 , race/ethnicity15,23, taste receptor genotype19,24, family history of alcoholism20,25, and depressive symptomatology among pediatric populations20. In addition, sweet taste preference as measured by this method is associated with preference for sugar in foods and beverages15,19,21,22, providing evidence of criterion-related validity and a measure of insight into the association between an individual&#39;s sweet preference and their dietary sugar intake.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Sucrose</td>
			<td>Spectrum Chemical Mfg Corp</td>
			<td>SU103</td>
			<td></td>
		</tr>
		<tr>
			<td>Distilled water</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Corning Pyrex 1000 ml Class A Volumetric Flask</td>
			<td>Spectrum Chemical Mfg Corp</td>
			<td>988-24433</td>
			<td></td>
		</tr>
		<tr>
			<td>Boston Round 1000 ml Amber Glass Bottle</td>
			<td>Spectrum Chemical Mfg Corp</td>
			<td>842-17040</td>
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		<tr>
			<td>Boston Round 125 ml Amber Glass Bottle</td>
			<td>Spectrum Chemical Mfg Corp</td>
			<td>842-17031</td>
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			<td>Heathrow Scientific Multi-Function Stopwatch</td>
			<td>Spectrum Chemical Mfg Corp</td>
			<td>140-75046</td>
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			<td>McKesson Medi-Pack Medicine Cups</td>
			<td>Amazon</td>
			<td>46941200</td>
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			<td>Solo drinking cups</td>
			<td>Amazon</td>
			<td>SCCP16RLR</td>
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		</tr>
	</tbody>
</table>

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.

Figure 2 contains the tracking grid results from one representative subject. This subject&#39;s most preferred level of sucrose, 4.2% w/v, was determined by calculating the geometric mean of the sucrose concentrations chosen in Series 1 (6% w/v) and Series 2 (3% w/v). In cases where the subject only completes one of the series, the geometric mean obviously cannot be calculated. Further analysis can focus on data obtained from Series 1 separately from Series 215.
Figure 3 summarizes data collected from 930 individuals ranging in age from 5 to 55 years15.Children and adolescents prefer more concentrated sweetness (~19% wt/vol sucrose solution) than adults (~14% wt/vol). Where the adults&#39; most preferred level of sucrose is similar to the sugar content of a typical soda (~11% wt/vol or 39 g/355 ml), one would have to add 28 g (seven teaspoons) to a standard 355 ml can of soda to approximate children&#39;s most preferred level.
<img alt="Figure 2" src="/files/ftp_upload/54163/54163fig2.jpg" />

Figure 2. A subject performing the sucrose preference test and a tracking grid containing representative data from one subject. (A) A pair of sucrose solutions is placed on the table in front of the subject in the order to be tasted. The subject is asked to taste the solution in position 1 for 5 sec, to expectorate, to rinse her mouth with water, and to repeat for the solution in position 2. After tasting both solutions, the subject is asked to point to the solution that she likes better, and to rinse her mouth twice with water. (B) The first solution of the pair tasted by the subject is underlined, and the subject&#39;s choice is circled. In Series 1, testing ended when the subject chose solution B when it was paired with both a higher and lower concentration of sucrose. In Series 2, testing ended when the subject chose solution A (the lowest concentration solution) twice consecutively. (C) Determination of the subject&#39;s preferred level of sucrose is estimated by calculating the geometric mean of the final concentration chosen in each series. The figure has been modified from Mennella, J. A., Lukasewycz, L. D., Griffith, J. W., Beauchamp, G. K. Evaluation of the Monell forced-choice, paired-comparison tracking procedure for determining sweet taste preferences across the lifespan. Image has been reproduced with permission15. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54163/54163fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

<img alt="Figure 3" src="/files/ftp_upload/54163/54163fig3.jpg" /> 
Figure 3. The most preferred level of sucrose (% wt/vol). These data were obtained from calculating the geometric mean (Geo Mean) from both Series 1 and Series 2 among children (5-10 years, N=338), adolescents (10-20 years, N=168), and adults (20-55 years, N=424). Error bars represent standard errors of the means. *Significantly different from children and adolescent groups. Data from15. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54163/54163fig3large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Solution</td>
			<td>% (w/v)</td>
			<td>w (g sucrose) in 1,000 ml water</td>
		</tr>
		<tr>
			<td>A</td>
			<td>3</td>
			<td>30</td>
		</tr>
		<tr>
			<td>B</td>
			<td>6</td>
			<td>60</td>
		</tr>
		<tr>
			<td>C</td>
			<td>12</td>
			<td>120</td>
		</tr>
		<tr>
			<td>D</td>
			<td>24</td>
			<td>240</td>
		</tr>
		<tr>
			<td>E</td>
			<td>36</td>
			<td>360</td>
		</tr>
	</tbody>
</table>
Table 1. Concentrations of sucrose solutions for the preference test.

Watch this Scientific Journal Video about Psychophysical Tracking Method to Measure Taste Preferences in Children and Adults at JoVE.com

Psychophysical Tracking Method to Measure Taste Preferences in Children and Adults

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 ...

psychophysical-tracking-method-to-measure-taste-preferences-children

Nanyang Technological University

Research

JoVE Journal

Behavior

17.6K Views.  Monell Chemical Senses Center. 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.

Video: Psychophysical Tracking Method to Measure Taste Preferences in Children and Adults

The Crossmodal Congruency Task as a Means to Obtain an Objective Behavioral Measure in the Rubber Hand Illusion Paradigm

The rubber hand illusion (RHI) is a popular experimental paradigm. Participants view touch on an artificial rubber hand while the participants' own hidden hand is touched. If the viewed and felt touches are given at the same time then this is sufficient to induce the compelling experience that the rubber hand is one's own hand. The RHI can be used to investigate exactly how the brain constructs distinct body representations for one's own body. Such representations are crucial for successful interactions with the external world. To obtain a subjective measure of the RHI, researchers typically ask participants to rate statements such as "I felt as if the rubber hand were my hand". Here we demonstrate how the crossmodal congruency task can be used to obtain an objective behavioral measure within this paradigm.
The variant of the crossmodal congruency task we employ involves the presentation of tactile targets and visual distractors. Targets and distractors are spatially congruent (i.e. same finger) on some trials and incongruent (i.e. different finger) on others. The difference in performance between incongruent and congruent trials - the crossmodal congruency effect (CCE) - indexes multisensory interactions. Importantly, the CCE is modulated both by viewing a hand as well as the synchrony of viewed and felt touch which are both crucial factors for the RHI.
The use of the crossmodal congruency task within the RHI paradigm has several advantages. It is a simple behavioral measure which can be repeated many times and which can be obtained during the illusion while participants view the artificial hand. Furthermore, this measure is not susceptible to observer and experimenter biases. The combination of the RHI paradigm with the crossmodal congruency task allows in particular for the investigation of multisensory processes which are critical for modulations of body representations as in the RHI.

We demonstrate how an objective measure can be employed in the widely employed rubber hand illusion paradigm. This measure is obtained by modifying the well-established crossmodal congruency task. This task allows the investigation of multisensory processes which are critical for modulations of body representations as in the rubber hand illusion.

The rubber hand illusion (RHI) is a popular experimental paradigm. Participants view touch on an artificial rubber hand while the participants' own hidden ...

Uncovering Beat Deafness: Detecting Rhythm Disorders with Synchronized Finger Tapping and Perceptual Timing Tasks

A set of behavioral tasks for assessing perceptual and sensorimotor timing abilities in the general population (i.e., non-musicians) is presented here with the goal of uncovering rhythm disorders, such as beat deafness. Beat deafness is characterized by poor performance in perceiving durations in auditory rhythmic patterns or poor synchronization of movement with auditory rhythms (e.g., with musical beats). These tasks include the synchronization of finger tapping to the beat of simple and complex auditory stimuli and the detection of rhythmic irregularities (anisochrony detection task) embedded in the same stimuli. These tests, which are easy to administer, include an assessment of both perceptual and sensorimotor timing abilities under different conditions (e.g., beat rates and types of auditory material) and are based on the same auditory stimuli, ranging from a simple metronome to a complex musical excerpt. The analysis of synchronized tapping data is performed with circular statistics, which provide reliable measures of synchronization accuracy (e.g., the difference between the timing of the taps and the timing of the pacing stimuli) and consistency. Circular statistics on tapping data are particularly well-suited for detecting individual differences in the general population. Synchronized tapping and anisochrony detection are sensitive measures for identifying profiles of rhythm disorders and have been used with success to uncover cases of poor synchronization with spared perceptual timing. This systematic assessment of perceptual and sensorimotor timing can be extended to populations of patients with brain damage, neurodegenerative diseases (e.g., Parkinson&#8217;s disease), and developmental disorders (e.g., Attention Deficit Hyperactivity Disorder).

Behavioral tasks that allow for the assessment of perceptual and sensorimotor timing abilities in the general population (i.e., non-musicians) are presented. Synchronization of finger tapping to the beat of an auditory stimuli and detecting rhythmic irregularities provides a means of uncovering rhythm disorders.

A set of behavioral tasks for assessing perceptual and sensorimotor timing abilities in the general population (i.e., non-musicians) is presented here ...

Measuring Attentional Biases for Threat in Children and Adults

Investigators have long been interested in the human propensity for the rapid detection of threatening stimuli. However, until recently, research in this domain has focused almost exclusively on adult participants, completely ignoring the topic of threat detection over the course of development. One of the biggest reasons for the lack of developmental work in this area is likely the absence of a reliable paradigm that can measure perceptual biases for threat in children. To address this issue, we recently designed a modified visual search paradigm similar to the standard adult paradigm that is appropriate for studying threat detection in preschool-aged participants. Here we describe this new procedure. In the general paradigm, we present participants with matrices of color photographs, and ask them to find and touch a target on the screen. Latency to touch the target is recorded. Using a touch-screen monitor makes the procedure simple and easy, allowing us to collect data in participants ranging from 3 years of age to adults. Thus far, the paradigm has consistently shown that both adults and children detect threatening stimuli (e.g., snakes, spiders, angry/fearful faces) more quickly than neutral stimuli (e.g., flowers, mushrooms, happy/neutral faces). Altogether, this procedure provides an important new tool for researchers interested in studying the development of attentional biases for threat.

Here we describe a touch-screen visual search paradigm that can be used to study threat detection across the lifespan. The paradigm has already been used in various studies demonstrating that both children and adults detect threatening stimuli like snakes, spiders, and angry faces faster than non-threatening stimuli.

Investigators have long been interested in the human propensity for the rapid detection of threatening stimuli. However, until recently, research in this ...

A Treatment Package without Escape Extinction to Address Food Selectivity

Feeding difficulties and feeding disorders are a commonly occurring problem for young children, particularly children with developmental delays including autism. Behavior analytic interventions for the treatment of feeding difficulties oftentimes include escape extinction as a primary component of treatment. The use of escape extinction, while effective, may be problematic as it is also associated with the emergence of challenging behavior (e.g., extinction burst). Such challenging behavior may be an acceptable side effect in treatment cases where feeding problems are severe and chronic (e.g., failure to thrive). However, in more acute cases (e.g., selective eating), the negative side effect may be unwarranted and undesired. More recent research on the behavioral treatment of food selectivity has begun to evaluate treatments for feeding difficulties that do not include escape extinction (e.g., demand fading, behavioral momentum), with some success. However, research to date reveals individual differences in responsiveness to such treatments and no clear preferable treatment has emerged. This manuscript describes a multi-component treatment package that includes shaping, sequential presentation and simultaneous presentation, for the treatment of food selectivity in four young children with developmental delays. This treatment package extends the literature on the behavioral treatment for food selectivity and offers a multi-component treatment protocol that may be clinically applicable across a range of treatment scenarios and settings.

Feeding difficulties are a common problem for children with developmental disorders, including autism, and behavioral interventions often include escape extinction. Recent research has begun to evaluate treatments that do not include escape extinction. This manuscript describes a multicomponent treatment package that does not use escape extinction to treat feeding difficulties.

Feeding difficulties and feeding disorders are a commonly occurring problem for young children, particularly children with developmental delays including ...

Determining Ultrasonic Vocalization Preferences in Mice using a Two-choice Playback Test

Mice emit ultrasonic vocalizations (USVs) during a variety of conditions, such as pup isolation and adult social interactions. These USVs differ with age, sex, condition, and genetic background of the emitting animal. Although many studies have characterized these differences, whether receiver mice can discriminate among objectively different USVs and show preferences for particular sound traits remains to be elucidated. To determine whether mice can discriminate between different characteristics of USVs, a playback experiment was developed recently, in which preference responses of mice to two different USVs could be evaluated in the form of a place preference.
First, USVs from mice were recorded. Then, the recorded USVs were edited, trimmed accordingly, and exported as stereophonic sound files. Next, the USV amplitudes generated by the two ultrasound emitters used in the experiment were adjusted to the same sound pressure level. Nanocrystalline silicon thermo-acoustic emitters were used to play the USVs back. Finally, to investigate the preference of subject mice to selected USVs, pairs of two differing USV signals were played back simultaneously in a two-choice test box. By repeatedly entering a defined zone near an ultrasound emitter and searching the wire mesh in front of the emitter, the mouse reveals its preference for one sound over another. This model allows comparing the attractiveness of the various features of mouse USVs, in various contexts.

Ultrasonic vocalizations (USVs) in mice differ depending on age, sex, condition, and genetic background. Using two ultrasound emitters broadcasting simultaneously in different locations, this two-choice test can evaluate murine recognition and preference responses to different characteristics of USVs.

Mice emit ultrasonic vocalizations (USVs) during a variety of conditions, such as pup isolation and adult social interactions. These USVs differ with age, ...

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 ...

Assessing Working Memory in Children: The Comprehensive Assessment Battery for Children &#8211; Working Memory (CABC-WM)

The Comprehensive Assessment Battery for Children - Working Memory (CABC-WM) is a computer-based battery designed to assess different components of working memory in young school-age children. Working memory deficits have been identified in children with language-based learning disabilities, including dyslexia1,2 and language impairment3,4, but it is not clear whether these children exhibit deficits in subcomponents of working memory, such as visuospatial or phonological working memory. The CABC-WM is administered on a desktop computer with a touchscreen interface and was specifically developed to be engaging and motivating for children. Although the long-term goal of the CABC-WM is to provide individualized working memory profiles in children, the present study focuses on the initial success and utility of the CABC-WM for measuring central executive, visuospatial, phonological loop, and binding constructs in children with typical development. Immediate next steps are to administer the CABC-WM to children with specific language impairment, dyslexia, and comorbid specific language impairment and dyslexia.

Working memory predicts a significant amount of variance for a variety of cognitive tasks, including speaking, reading, and writing. However, few tools are available to assess working memory in children. We present an innovative, computer-based battery that comprehensively assesses different components of working memory in school-age children.

The Comprehensive Assessment Battery for Children - Working Memory (CABC-WM) is a computer-based battery designed to assess different components of ...

An Electrophysiology Protocol to Measure Reward Anticipation and Processing in Children

We present a protocol designed to measure the neural correlates of reward in children. The protocol allows researchers to measure both reward anticipation and processing. Its purpose is to create a reward task that is appropriate for young children with and without autism while controlling reward properties between two conditions: social and nonsocial. The current protocol allows for comparisons of brain activity between social and nonsocial reward conditions while keeping the reward itself identical between conditions. Using this protocol, we found evidence that neurotypical children demonstrate enhanced anticipatory brain activity during the social condition. Furthermore, we found that neurotypical children anticipate social reward more robustly than children with autism diagnoses. As the task uses snacks as a reward, it is most appropriate for young children. However, the protocol may be adapted for use with adolescent or adult populations if snacks are replaced by monetary incentives. The protocol is designed to measure electrophysiological events (event-related potentials), but it may be customized for use with eye-tracking or fMRI.

This protocol is designed to measure reward anticipation and processing in young children with and without autism. Specifically, the protocol is designed to study the neural correlates of reward during social and nonsocial conditions while controlling for reward between conditions.

We present a protocol designed to measure the neural correlates of reward in children. The protocol allows researchers to measure both reward anticipation ...

Elevated Plus Maze Test Combined with Video Tracking Software to Investigate the Anxiolytic Effect of Exogenous Ketogenic Supplements

The overall goal of this study is to describe the methodology of the elevated plus maze (EPM) test in combination with a video tracking software. The purpose of the method is to document the effect of various potential anxiolytic treatments on laboratory rodent models. The EPM test is based on the rodents&#39; proclivity toward protected, enclosed dark spaces and unconditioned fear of open spaces and heights, and their innate intense motivation to explore novel environments. The EPM test is a widely used behavioral test for investigating the anxiolytic or anxiogenic responses of rodents given drugs that are known to affect behavior. Observation demonstrating a decreased proportion of time spent on closed arms, an increased proportion of time spent on open arms, a reduced number of entries to closed arms, and an elevated number of entries to open arms measured by the EPM test may reflect reduced anxiety levels. Using this method, the effect of exogenous ketone supplements on anxiety-related behavior is tested in Sprague Dawley (SPD) rats. Exogenous ketone supplements are chronically fed to the rats for 83 days or subchronically and acutely orally gavaged, daily for 7 days, before conducting the EPM test. Behavioral data collection is performed using the SMART video tracking system by a blinded observer at the end of the treatments. The main findings indicate that the EPM test is an effective method to detect the ketone supplement-induced anxiolytic effect and can be considered a sensitive measure to assess changes in anxiety behavior associated with drug- or metabolic-based therapies.

Here, we present a protocol to investigate changes in the anxiety level of rodent animal models. The elevated plus maze (EPM) test, used together with a video tracking software, provides a reliable method to document the effect of various potential anxiolytic treatments in preclinical laboratory scenarios.

The overall goal of this study is to describe the methodology of the elevated plus maze (EPM) test in combination with a video tracking software. The ...

Comparing Eye-tracking Data of Children with High-functioning ASD, Comorbid ADHD, and of a Control Watching Social Videos

Children with autism spectrum disorders (ASD) are known to have sensory-perceptual processing deficits that weaken their abilities to attend and perceive social stimuli in daily living contexts. Since daily social episodes consist of subtle dynamic changes in social information, any failure to attend to or process subtle human nonverbal cues, such as facial expression, postures, and gestures, might lead to inappropriate social interaction. Traditional behavioral rating scales or assessment tools based on static social scenes have limitations in capturing the moment-to-moment changes in social scenarios. An eye-tracking assessment, which can be administered in a video-based mode, is therefore preferred, to augment clinical observation. In this study, using the single-case comparison design, the eye-tracking data of three participants, a child with autism spectrum disorder (ASD), another with comorbid attention deficit-hyperactive disorder (ADHD), and a neurotypical control, are captured while they view a video of social scenarios. The eye-tracking experiment has helped answer the research question: How does social attention differ between the three participants? By predefining areas of interest (AOIs), their visual attention on relevant or irrelevant social stimuli, how fast each participant attends to the first social stimuli appearing in the videos, for how long each participant continues to attend to those stimuli within the AOIs, and the gaze shifts between multiple social stimuli appearing concurrently in the same social scene are captured, compared, and analyzed in a video-based eye-tracking experiment.

This is a qualitative comparative case study analysis of eye-tracking data on the first moments of social video scenes as viewed by three participants: one with autism spectrum disorder, one with comorbid attention deficit-hyperactive disorder, and one neurotypical control.

Children with autism spectrum disorders (ASD) are known to have sensory-perceptual processing deficits that weaken their abilities to attend and perceive ...