=Paper=
{{Paper
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|storemode=property
|title=Nudging the Cart in the Supermarket: How much is Enough Information for Food Shoppers?
|pdfUrl=https://ceur-ws.org/Vol-690/paper6.pdf
|volume=Vol-690
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==Nudging the Cart in the Supermarket: How much is Enough Information for Food Shoppers?==
https://ceur-ws.org/Vol-690/paper6.pdf
Nudging the cart in the supermarket:
How much is enough information for food shoppers?
Peter M. Todd Yvonne Rogers Stephen J. Payne
Indiana University The Open University University of Bath
Bloomington Milton Keynes Bath
IN 47406, USA MK7 6AA, UK BA2 7AY, UK
001 812 855-3914 011 44 1908 652346 011 44 1225 384085
pmtodd@indiana.edu y.rogers@open.ac.uk s.j.payne@bath.ac.uk
ABSTRACT about? Technology pundits and researchers are beginning to
The amount of information available to help decide what foods to promote ‘augmented reality’ that uses Smartphones and other
buy and eat is increasing rapidly with the advent of concerns ubiquitous technologies as the latest solution to this problem.
about, and data on, health impacts, environmental effects, and Kuang [7], for example, marvels at the possibility: “What if all
economic consequences. But this glut of information can be the food in your grocery store was marked with a QR code — you
distracting or overwhelming when presented within the context of could compare the carbon footprints of two batches of produce…
a high time-pressure, low involvement activity such as without having to spend any time or effort looking it up…” He
supermarket shopping. How can we nudge people’s food continues by claiming it is “The best chance we have to speed
shopping behavior in desired directions through targeted delivery crucial information about our world to the people living in it”.
of appropriate information? We are investigating whether This vision, however, begs the research questions: Will people be
augmented reality can deliver relevant 'instant information', that able to read and act upon such ‘instant information’? Will just
can be interpreted and acted upon in situ, enabling people to make throwing more information at people have the desired galvanizing
more informed choices. The challenge is to balance the need to effect of encouraging and empowering people to act upon various
simplify and streamline the information presented with the need social causes (e.g., reducing carbon emissions) or improve their
to provide enough information that shoppers can adjust their well-being (e.g., changing their diet)? Or do we need to tailor
behavior toward meeting their goals. that information glut into simple nudges that make behavior
change easy to achieve? And if so, what kind of nudges will work?
Categories and Subject Descriptors Having instant information at one’s fingertips is certainly a
promising technological approach but for it to succeed in
H.5.2 [User Interfaces]: Evaluation/methodology.
changing people’s behavior we need to understand how new
forms of augmented reality are interpreted and used, especially
General Terms when in situ. While the capabilities of the emerging technologies
Design, Experimentation, Human Factors. are impressive in how they can project contextualised
information, there is a paucity of research into whether people can
Keywords process and exploit that extra information profitably. While it is
Food information displays, supermarket shopping, ambient easy to imagine soda drinkers enjoying the surprise of being
information interfaces, simple heuristics presented with a new branded game or a funny website on their
mobile phone it is less clear whether people will make greener
and healthier choices whilst managing their weekly budget when
1. INTRODUCTION presented with extra information of one form or another in the
Increasingly we are told about the risks, costs, and benefits of middle of their busy shopping trip. Thus, research is needed,
particular food choices. In response, a flood of information is firstly, to determine whether instant information will enable
becoming available, online, on food labels, in information leaflets people to make better-informed choices when shopping and
and books, from a variety of sources, aimed at informing the secondly, to ascertain whether and how such information is able
consumer so that better decisions can be made while shopping. to change people’s behavior in the longer term.
But all this information risks overwhelming and overloading the
Technology for ubiquitous information delivery must balance
shopper trying to navigate the complex store environment in a
giving people enough new information to improve their decisions
hurry, leading to the opposite outcome—poor decisions made
against overwhelming them with new things to consider. Ambient
without the proper input. How can all this information be
information displays, as already used in homes and offices to
consolidated, pruned down, and presented to supermarket
provide feedback about energy consumption and nudge users
shoppers in an easy to understand and meaningful form that will
toward greater conservation, may strike the right balance in food
actually help them make better choices about values they care
purchase and consumption as well. However, as we discuss
Copyright is held by the author/owner(s).
MobileHCI 2010 September 7-10, 2010, Lisboa, Portugal. below, moving beyond momentary nudges toward long-term
ACM 978-1-60558-835-3/10/09.
behavior change requires providing detailed-enough feedback to More recently, Bargrams have been developed for e-commerce
enable learning what to do in the future, for instance on the next applications. For example, EZChooser helps consumers choose
shopping trip. We argue that we must improve our (currently one item from many (e.g., cars) through selecting attributes that
limited) understanding of whether and how people attend to and are visualized as parallel horizontal interactive histograms along a
learn from visualizations of multi-dimensional information while number of dimensions [16].
engaged in an ongoing activity such as food shopping, using But even though these kinds of visualizations are mostly targeted
cognitive science models of decision-making and learning at non-expert users, they are essentially visual query languages
together with design principles for information visualization and that require considerable cognitive effort to interpret. Can relevant
interaction design. dimensions of products such as food be represented in simple
ways that can be glanced at and perceived rapidly to guide
2. BACKGROUND shopping decisions in situ?
Rational theories of decision-making [e.g., 15] posit that making a
choice involves weighing up the costs and benefits of different 3. DISPLAYING NUDGES
courses of action. When alternatives are ordered on more than one We propose that rather than providing ever more information to
relative dimension, this involves compensatory strategies where enable consumers to compare products in minute detail when
information is processed exhaustively and trade-offs made making a choice, a better strategy is to design technological
between features. Such strategies are very costly in computational interventions that provide just enough information and in the right
and informational terms – not least because they require the form to facilitate good choices. One solution is to exploit new
decision-maker to find a way to compare apples and oranges. forms of augmented reality technology that enable ‘information-
Non-compensatory strategies may be used instead as a form of frugal’ decision-making, in the context of an intensive activity
bounded rationality where not all of the available information is replete with distractions (i.e., shopping in a supermarket or
used and trade-offs can be ignored [10]. Furthermore, recent deciding at the kitchen table what to have for dinner).
research in cognitive psychology has shown people tend to use An important consideration when representing multiple
simple heuristics of this sort when making decisions [6]. A dimensions that can be glanced at and perceived rapidly is to
theoretical explanation is that human minds have evolved to act enable comparisons to be made and cumulative information
quickly, making ‘just good enough’ decisions by using fast and inferred in situ. For example, simple contrasting icons (e.g.,
frugal heuristics. We typically ignore most of the available thermometer icons, percentage bars, balls that change in color)
information and rely only on a few important cues. In the can be presented which increase or decrease in amount in relation
supermarket, shoppers make snap judgments based on a paucity to the values being represented. Another approach is to fuse
of information, such as buying brands they recognize, are low- relative measures on different dimensions (e.g., greenness, price,
priced, or have attractive packaging [12] – seldom reading other fat level) into singular displays where shape carries the salient
package information. information, such as a rectangle that gets taller to convey a
At the same time, recent consumer surveys reveal that shoppers nutritional dimension that is general (healthiness) or specific (e.g.,
are demanding more information about the products they buy and salt content) and wider to convey price. A third dimension, such
are becoming increasingly aware of the global consequences of as ‘greenness’, could be added by filling in the rectangle with a
the decisions they make [4]. This raises the question of whether it shade from red to green to show the amount of carbon emissions
is possible to encourage people to pay attention to more for that product. Similar to the idea behind Chernoff faces, the
information, such as nutritional, ethical, and environmental visualizations will be placed side by side to enable quick
features, when making their food purchases and subsequently comparisons.
deciding how to use what they have bought to make healthy meals Another important question is whether to use ‘emotive’
that have a low carbon footprint. visualizations that can persuade people to select food items they
However, there is a scarcity of research on how people use multi- might not otherwise choose. Various persuasive technologies have
dimensional information under time pressure and the extent to recently been developed to encourage people to take more
which it effects rapid decision-making [5]. Visualization research exercise. Examples include Fish‘n’Steps [8]; Chick Clique ([13]
has tended to adopt an unbounded rationality perspective, and UbiFit [2] where various types of graphic representations
assuming that people have the time and cognitive capacity to pull (e.g., butterflies, flowers, bar charts) are used to represent amount
out and use whatever information the displays provide. Within the of exercise type performed, e.g., cardio, strength training, and
field of Information Visualization there have been a number of walking. Findings from a three-month field trial of UbiFit showed
tools that have been developed specifically to represent that these display systems can be motivating, encouraging
multidimensional data that allow for comparisons [1]. Other participants to maintain fitness levels that were significantly
simple canonical forms such as tables and trend graphs have been higher than for a control group without the visualizations [3].
developed for web-based decision-making activities, including
More dramatically, Shultz et al. [11] have shown how emoticons
online shopping, making investments, choosing insurance policies
can have a powerful effect on changing behavior for energy
or buying a house. An innovative approach has been to develop
consumption. In their study, a number of householders were told
interactive visualizations that show some aspects of the
exactly how much energy they had used and the average
performance of objects for a range of different parameter values.
consumption of energy by others in their neighborhood. The
An early example was the Influence Explorer [14] that allowed a
above-average energy users then significantly decreased their
user to compare how products (e.g., a light bulb) perform on core
energy use while the below-average energy users significantly
values (e.g., brightness and working life) when varying multiple
increased theirs (presumably because they felt they had more
parameters (e.g., diameter, length, material and number of coils).
room to increase their consumption). But then the researchers them feel good in front of other shoppers [11]? Would the
tested the effect of instead giving householders who consumed prospect of others seeing just how much butter and cheese they
more than average an unhappy smiley icon – suggesting it was are buying make shoppers think about buying less, or just
socially disapproved – and those who consumed less than the thinking about shopping elsewhere?
norm a happy smiley icon – suggesting their energy consumption Assuming such an ambient information display Cumulative Tool
was socially approved. The impact of providing these two achieves the desired features of providing some feedback without
visualizations was dramatic: The big energy users showed an even overloading the decision maker, without undesired effects of
larger decrease in their energy use while the below-average users scaring shoppers off or making them “boomerang” and offset their
did not change their energy consumption upward (presumably good behavior with poorer choices, the question remains whether
because the addition of the happy emoticon suggested they were this kind of simple display provides enough feedback to allow the
doing just fine). shopper to adjust behavior in the desired direction, e.g. reduced
sodium or enhanced green-ness. Seeing that one’s entire cart is
4. LEARNING FROM NUDGES red-lining above the goal level may motivate behavior, but it does
What then is a good way to provide appropriate information not directly indicate what to do to bring the level back down.
quickly and simply to shoppers in order to aid their decision- Thus, we must develop and test methods for ensuring that the
making during the hectic, distracting setting of a trip to the (minimal) information delivered is actually actionable and
supermarket? Here we assume the shoppers have selected a conducive to behavior change.
particular dimension that they care about and want to change in
terms of their buying behavior—for instance, choosing products There are at least three approaches that can be taken to solving
that are lower fat, or more sustainably grown. To inform shoppers this problem, which is essentially one of allocating global
about how they are doing in achieving this particular goal during feedback appropriately to individual choices of products (akin to
their shopping expedition, cumulative values of the dimensions of the “credit assignment” problem in machine learning). First, we
interest across all products chosen so far could be summed up and could leave it all up to the users, and assume (or hope) that when
displayed in an ambient manner as the current ongoing overall they end their shop with a “green” cart, they will buy more things
score “projected” onto the handle of the shopping cart as a color. like those the next time around, and when they get a “red” cart,
For example, a green handle could signify that the shopper has they will buy different things next time. This leverages the
obtained a ‘carbon footprint’ or ‘fat content’ score below their human shopper’s intelligent ability to learn from diffuse
target (or below some population average), while a red handle reinforcement over time, but it will probably be slow, requiring
would indicate that the cart’s contents are above the desired level, many shopping outings before reliable change occurs. Second, to
with intermediate levels indicated by intermediate colors (see speed up this process, we could provide more specific feedback
Figure 1). about each product that goes into the cart, for instance
momentarily flashing the ambient display with a color
corresponding to the box of sugar-frosted chocolate bombs or bag
of figs being chosen. This will allow shoppers to make more
targeted decisions about each product, provided they remember
that individual feedback.
Third, to remove the need for such memory, a further interface
can be developed to let shoppers query how they should adjust
their purchases to come closer to their goal. This could take two
main forms. A Comparative Tool could run as a ‘private’ mobile
application on a smartphone or PDA and be displayed on the
device or somewhere in the environment, such as the shopper’s
hand or the product package itself. After identifying the product
via a photo or code scanner, the tool will show the product values
on the dimensions of interest, and indicate whether this product
Figure 1: Two hypothetical shopping carts with (a) red and helps or hinders the achievement of the current shopping goal.
(b) green glowing handles, indicating aggregate ‘healthiness’ This interface could also be used in a comparative manner,
of products selected relative to the average for a weekly shop scanning two or more products while they are still on the shelf
for a family of four and then showing at a glance which product is best based on the
selected dimensions.
Such an ambient and publicly visible display must first be studied As a second ‘off-line’ form of providing more explicit feedback, a
to see if it fits with how people want to shop, or engenders Collaborative Tool running on a home computer or surface
unexpected side-effects. Will people be more or less likely to display would allow shoppers to find out further information
change their behavior when information about the contents of about the products they have bought once they get them home,
their shopping cart is publicly visible for all to see rather than along with input from their families. Multiple users could reflect
being privately displayed? Would shoppers try to fill their cart and discuss together the decisions behind their food purchases
with healthy and green foods and on finding they were under the with a view to attaining their goals at their next weekly shop,
average then treat themselves to luxury goods high in fat and food exploiting collaborative planning and social pressures that take
miles? Would having their shopping cart glow green at the check- place in a family setting. An interactive planner application would
out, indicating the contents were well below the average, make enable family members to find out more about particular
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