Sensory Primes for Sustainable Eating

Your plate arrives. The delicious aroma wafts toward you before you even see the dish. Your mouth waters.

Placed down, your eyes absorb the portion in front of you, the blend of colors, and the quality of ingredients. You sense the heat from the plate, hear the sizzle of food, and your stomach gurgles in anticipation.

There's no question that the sight of a tasty meal can kickstart our appetite. This fact is well exploited by food marketers who promote their products with compelling photographs—large, hyper-coloured images of juicy burgers, oozing with sauce, or oven-crisp golden pizza with melting cheese.

Knowing exactly when and how to use such images is not only beneficial for food businesses, but it is also a hugely under-leveraged technique for those working to promote more sustainable diets worldwide.

Our food system contributes to around one-third of all global greenhouse gas emissions, with meat and dairy products having an outsized negative impact on the environment. Recent research suggests that emissions from food alone will likely prevent global temperature rises from staying within the "safe operating space" of <2°C, as defined under the Paris Agreement. As a result, far deeper and more widespread changes to our collective diets are urgently needed; in particular, eating more resource-efficient, plant-rich foods and fewer animal-based products.

It is a simple goal to state, but one that is much harder to achieve in practice.

Non-Conscious Priming and Food Choice

It is here that non-conscious, sensory "primes," such as compelling food images, can play a valuable role. Priming refers to the act of exposing someone to a cue (or "stimulus") that predisposes them towards a subsequent object (or "target"). This association happens automatically and below our conscious awareness.

Images work incredibly well as food choice primes, as do indulgent, taste-focussed menu descriptions. Both techniques trigger us to simulate eating in our imaginations, so whetting our appetites, and have been proven to motivate diners to select more plant-rich meals.

Less well-known, however, is the effect of other sensory primes that target sight, as well as smell and sound, to encourage people to select lower-emitting foods.

Touch and taste are, of course, relevant, but seemingly more important post- rather than pre-choice, where taste, texture, and mouthfeel will all determine the likelihood of repeat food purchases.

From Typeface to Tablecloths

When it comes to viewing written words on menus, it’s not only the content that matters for food choice; something as seemingly unimportant as a typeface can also prove influential.

It seems that we implicitly associate differently shaped food with distinct taste profiles. Roundness is linked to sweeter tastes, for example, while angular items evoke sourness or spice. Research has demonstrated a clear "congruence effect" here, whereby consumers report more favourable attitudes, and greater intentions to purchase, round-shaped foods described on menus using a rounded font, and angular foods presented in an angular font.

While no research has explicitly studied the role of typefaces in promoting sustainable options, it would follow that matching typefaces to taste expectations, such as identifying fonts that evoke the ideas of freshness or fillingness of plant-rich meals, could be a potentially effective promotional tool.

The colour and balance of ingredients matter, too. For example, another new study has demonstrated that colour can influence decisions to consume plant-rich meals. In this trial, diners were more likely to opt for vegetarian options when meat-heavy meals were present on red-colored tables, rather than on green ones, in part because the red background decreased the visual attractiveness of the meat.

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Making Sound Choices

Beyond our eyes, our ears also have an important yet under-exploited influence on our perceptions of food. Congruence again plays a role here, with sounds that match taste expectations (i.e., a rustle of a crisp packet, crunchy white noise with fresh crudité) shown to enhance eating experiences.

One other possible explanation for this effect is cross-transference between physiological arousal, emotions, and taste perceptions. For example, louder, stressful industrial noises have been linked to more negative eating experiences compared to softer, more soothing natural sounds, while heightened sweet and pleasant tastes are observed when food is consumed to natural soundtracks, and higher bitterness is found with machine noises.

Interestingly, natural sounds (i.e., waves, bird songs) and calming music have both been associated with a greater liking of plant-based items, including fruit and vegetables. This is possibly due to the music’s relaxing effect, which helps to avoid cognitive depletion and supports more reflective, value-driven choices.

It's All Good Scents

Smell is one of the most potent of our senses and is critical to our experience of food. In terms of choice, new research again demonstrates a congruence effect, finding that people's eyes go first to those menu items whose taste (i.e., sweet or savoury) matches that of a surrounding odour. Other emerging work indicates that smell may prove to be a more powerful influence on food selection than sight, boosting desire to a greater extent when wafted towards hungry diners in a highly motivated and receptive state.

Overall, the significant influence of non-conscious, sensory primes on food choice has been consistently proven across a body of compelling research, yet hardly explored in the context of promoting more sustainable diets. Right now, this represents an important missed opportunity and a new horizon for environmentally-minded culinarians and sustainability advocates who can work to better pique our senses, rather than just appeal to our better selves, to create the dietary shift we so urgently need.