Table.

Examples of types of psychophysical tools used to assess bitter taste and medication palatability in pediatric populations.

Method	Age of Subjects	Measures	Outcome Measures	Key References
Facial reactivity	All ages, but facial reactivity as an indicator becomes less reliable with age181	The number of affective reactions infants express to a taste stimulus is quantified as a measure of the valence and intensity of an affective reaction. Facial expressions are dissected into constituent action units (AUs) via slow-motion video analysis by trained raters.	Bitter solutions elicit upper and midface Aus (including cheek raises (AU 6) and gaping (AU 26 and AU 27)).	Oster and Rosenstein 1988115; Mennella et al. 2009128; Forestell and Mennella 2012125
Brief-access tests	Infancy (<1 year)	Infants are provided with brief access to two or more bottles in succession containing various bitter-tasting liquids or diluent.	Decreased intake to bitter taste.	Desor et al. 1975132; Kajiura et al. 1992130
Brief-access tests, multiple days	Infancy (<1 year)	Infants are fed food on multiple occasions; the days differ in the taste of the food presented.	Decreased intake to bitter-flavored relative to plain cereal.	Mennella et al. 2009128
Suckling response	Infancy (<1 year)	Patterning of suckling response measured while infant is feeding tastant versus diluent solutions; transducer may be embedded in nipple of bottle.	Retardation of suckling to bitter taste.	Kajiura et al. 1992130
Suprathreshold taste thresholds	Children ≥3 years of age	Subjects tasted (but did not swallow), solutions of PROP in ascending concentrations, rinsing with water before and after each tasting. Subjects are then classified into groups based on which concentration, if any, tasted bitter.	Variation in sensitivity to PROP related to TAS2R38 genotype and children’s food likes.	Anliker et al. 1991139; Mennella et al. 2005137
Scaling methods	Children ≥3 years of age	A variety of scaling methods are used during taste testing to evaluate children’s hedonic responses after tasting one solution at a time. Typically, the child is presented with a line or other type of scale that contains pictorial (e.g., faces ranging from frowns to smiles) or verbal descriptors to evaluate stimuli in a graded order.	Children (4–11 years) with kidney disease rated the taste of two different pulverized calcium channel blockers on a 5-point hedonic face scale to determine most palatable drug.148 Children (4–8 years) rated oral suspension of four antibiotics using a 5-point hedonic face scale to determine most preferred drug.149 Children (5–8 years) rated four antimicrobial agents using a 10-cm line with face labels placed above the line at approximately 0, 2.5, 5, 7.5, and 10 cm to determine the most palatable drug preparation.145 Caveat: unclear at what age children can comprehend these tasks.143	Powers et al. 2000149; Angelilli et al. 2000145; Milani et al. 2010148; Guinard 2001143