How do food manufacturers conduct sensory research on consumers too young to read, write, or make rational decisions?

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In 1995, Kraft expanded its line of packaged kids’ lunch combinations to include pizza-themed Lunchables despite negative reviews from parents who’d taste-tested the product. They found the application of cold pizza sauce, cold meat, and cold shredded cheese on cold crusts both unappetizing and incongruous with the steaming, oozy slices they associated with the word pizza.  Within a year, though, sales of the portable, build-it-yourself lunches had reached $150 million, and pizza Lunchables accounted for a quarter of the Lunchable brand’s total volume. Last year, the brand’s dollar sales reached $569 million.

Mothers and fathers may have been surprised, even as they threw boxes of the stuff into their shopping carts under duress, but Kraft wasn't. Unlike their parents, kids who had participated in trials during the product’s development loved both the idea of playing pizza chef and the taste of the meals.

Every children’s food manufacturer worth its salt knows that if the target market doesn't love a product, it will languish on shelves. Numerous studies have shown that children, and even toddlers, exact increasing influence over a family's food purchases. Researchers in Austria inconspicuously observed 178 parents shopping with their children and found that twice as many purchases in supermarkets were triggered by children than their parents are aware of. According to a report by market researcher Packaged Facts, kids between 3 and 11 years old collectively wielded $18 billion in purchasing power in 2005.

But how do food manufacturers conduct sensory research on preschoolers with difficulties focusing, or first-graders who are just coming to grips with reading—let alone babies and toddlers? By tailoring testing methodology to different groups of kids based on their age and abilities.

Unsurprisingly, it’s easiest to test foods on kids who are old enough to read and write about what they’re eating. For these children, ages 7 and older, researchers like those at Northland Sensory Insights, a consumer research facility in Northbrook, Ill., often use what are known formally as “verbal hedonic” scales, which incorporate age-appropriate language and are used in combination with pictorial scales (more on which below). About 25 years ago researchers conceived of the idea of using child-friendly colloquialisms on verbal hedonic scales, and a popular scale emerged in the late ’80s that included the phrases “super good” and super bad.”  This scale has been mostly abandoned, since “super bad” can now have a very different meaning. Instead, Northland has forsaken efforts to sound hip and now uses the much more straightforward “dislike very much” and “like very much” on tests administered to elementary- and middle-school kids on computers.

What about kids who are too young to read? For these, the pictorial scale—the mainstay of kids’ sensory research—is used in isolation. Pictorial scales can be simple and stylized—a common choice is a five-point star scale not dissimilar from the star systems some restaurant and movie critics use. Since kids as young as kindergarteners are used to receiving stars for good behavior or tasks well-done at school, the meaning of the star scale is usually pretty clear to them.

Another popular version is a more literal scale that relies on circular faces bearing expressions ranging from a face with a big open-mouthed smile with arched eyebrows (for “extreme liking”) to a straight-lined mouth (for “neither like nor dislike”) to an inverted smile (meaning “extreme dislike”).

Pictorial scales are a godsend for communicating with pre-literate children, but they also have drawbacks. Sometimes young children think that they are being asked which of the smiley faces best represents how they feel, not how much they like what they’re eating. (Also, the face for “extreme dislike” is interpreted by some to convey anger, which is confusing for children, most of whom don’t respond to even the yuckiest snacks with rage.) Some early versions of smiley faces included more features—different hairstyles, accessories, fleshed-out anatomical details—but kids found these peripheral features more engaging than the task of rating the food they were eating, so researchers toned down the add-ons. Cultural nuances also affect the usefulness of pictorial scales: Versions of the smiley-face scale that include tongues poking out—meant either as a sign that a food was lip-smackingly delicious or as an indication of disgust—have been deemed inappropriate for young product testers in Thailand and Malaysia, where it’s considered impolite to show your tongue.

One of the most creative pictorial scales ever developed is also, sadly, one of the least useful. In the 1980s, Bert Krieger, a researcher with a candy manufacturer, developed a scale with the Snoopy cartoon character in seven poses ranging from perky-eared ecstasy to droopy-eared disdain to elicit feedback from kids on recipe changes to chocolate bars. Snoopy only had a short run in testing circles, as children were both distracted and puzzled by his various incarnations.