The Lambent Shopping Trolley Handle clips onto any supermarket trolley and incorporates a display connected to a scanner to provide shoppers with nutritional, ethical and environmental product information. The display consists of 16 multi-colour LEDs which allow product information to be visualised via changes in pattern and colour. An inital lab-based study showed that the display can be read at a glance and used to select items based on a product’s properties. These product properties can be nominal (for example, it is organic or contains nuts), ordinal (for example, has low, medium or high food miles), as well as a combination of the two at the same time.
In the next study we investigated how shoppers use this technology in a real supermarket when doing their weekly shop. We found that when the Lambent Shopping Trolley Handle displayed the food miles of products, 72% of the time shoppers were nudged to select products with lower food miles compared to when they shopped without the handle. There was no nudge effect for shopper's favourite products (for example, a particular brand of chocolate) or items that they strongly disliked (for example, blue cheese). When shoppers saw that the average food miles of the items they had selected was above the norm, they tended to scan more proudcts and select ones with lower food miles.
This project is a collaboration with the Innovative Retail Lab and DFKI in Saarbrücken, Germany, the University of Bath, UK, and Indiana University, USA.
The following paper describes how the Lambent Shopping Trolley Handle works and gives details about the supermarket study we carried out:
Kalinikaité, V., Rogers, Y., Bird, J., Bachour, K., Villar, N., Payne, S., Todd, P. M., Schöning, J., Krüger, A. and
Kreitmayer, S. (2011) How to Nudge In Situ: Designing Lambent Devices to Deliver Information Salience in Supermarkets. Proceedings of Ubicomp, 11-20.
This paper provides information about bounded rationality - the theoretical framework that suggested that when people have limited time it is best to provide them with minimal information to support their decision making:
Todd, P. M, Rogers, Y. and Payne, S. (2011) Nudging the Trolley in the Supermarket: How to Deliver the Right Information to Shoppers. International Journal on Mobile HCI (IJMHCI), 3(2), 20-34.
Extensive research has shown that domestic energy usage can be reduced by providing households with feedback on their consumption. However, there are outstanding questions about the properties that make feedback eﬀective. Studies do suggest that the frequency of direct feedback appears to be positively correlated with saving behaviour, with continuous or daily feedback giving higher saving results than monthly feedback. This favours the use of technology-enabled interfaces that can provide regular and/or real time feedback versus paper based billing supplements.
The type of representation used for feedback is inﬂuential. For example, if it is too obvious and explicit it may be perceived as too personal, blunt or ‘in your face’, resulting in people objecting to it. An alternative approach is to provide simple representations that are more anonymous but striking and whose function is to attract people’s attention. In so doing it can make them think about the diﬀerent choices available to them, encourage reﬂection and even promote public debate about what is represented and how it affects them. However, if a representation is too abstract and implicit, it may be attributed other meanings, such as simply being an art piece, resulting in people ignoring it. The ideal may be somewhere in between. However what makes an eﬀective display and where and how those displays are best embedded in the environment are still open questions which we actively explored in a domestic energy usage project with households in Tidy Street, Brighton, UK.
In a study by Schultz and colleagues (2007), households were shown how their energy consumption compared to their neighbourhood average. This experiment clearly illustrates the power of social norms to aﬀect domestic energy usage: households above the average tended to decrease their consumption but those using less electricity than average tended to increase their consumption. The study found that this ‘boomerang eﬀect’ could be counteracted by providing households with an emoticon along with the numerical information about their energy usage: households using less energy than average continued to do so if they received a smiley icon; households using more than average decreased their consumption more if they were given a sad icon.
In contrast to the Schultz study, where each household’s energy consumption was kept private, our initial proposal was to explore how a household's energy consumption is aﬀected when they display their electricity usage in their front window so that it is visible to their neighbours and passersby. This was partly inspired by an art project done in Tidy Street by Lisa Creagh in 2006 where residents' front windows became large light boxes that display photographs chosen by the artist and participating households (see photo to the left).
In consultation with householders on Tidy Street, we proposed displaying both the average and real-time electricity consumption data for each participanting house: people walking down the street would be able to see pulsing displays that indicate how much electricity each household was currently using. Just as measuring a person’s pulse is a simple but eﬀective measure of their health, we hoped that these public displays would make visible the ‘energetic pulse’ of each household and give a public indication of their ‘environmental health’. A simple way to indicate current electricity usage is to use a light sensor to detect the frequency of the impulse light on a standard electricity meter (see photo to the left): the faster the pulse, the more electricity is being consumed.
However, residents, perhaps unsurprisingly, were not very enthusiastic about publicly displaying their electricity consumption, the primary reason being that they wanted this to be a community project and they were worried that the displays could be divisive, engendering competition rather than co-operation. We therefore explored what other types of information we could publicly display in the street that might lead to a reduction in domestic energy consumption, and how the public display might be used in conjunction with private displays that indicate electricity consumption to each household.
We initially explored how to display information about current demand on the electricity network and how we could represent this in order to encourage people to schedule various household chores (such as doing the washing) when there is less demand for electricity. This has environmental benefits and yet does not require participants to reduce their electricity consumption, just to think about when they consume energy. However, there were several challenges to address. First, where should we locate a public display so that it was highly visible, not vulnerable to theft or vandalism and also had access to an electricity supply. For example, one possible location we disused was sign arm above a shop at the north end of the street (see photo to the left). Second, could we find an easily understood visualization that represented both the current network demand and the current demand of the street. Third, what material form should the display use? One material we investigated was el wire (see photo to left) - a low energy and flexible material with neon-like properties. Although this is highly visible at night it is not very effective in sunlight.
Finally, we decided to create a large scale visualization of the street's electricity usage by spraying a display on the road surface using chalk spray. The design was created in collaboration with Brighton-based street artist Snub. For the first three weeks of the project we updated the public display each day and represented how the average electricity usage of the street compared to the Brighton average. We used a low-tech approach to measuring each household's electricity usage: asking them to read their meters each day and enter the reading into the project website. This website also provided each household with graphs showing how their electricity usage was changing over time.
After 3 weeks, the average electricity usage on Tidy Street had reduced by 15%. After 6 months, only three households were still regularly recording their electricity readings and two of these showed a significant reduction in electricity usage.
We are currently writing a journal paper about the Tidy Street project. However, a paper that outlines our motivation and initial ideas for the Tidy Street project is available for download:
Bird, J. and Rogers, Y. (2010) The Pulse of Tidy Street: Measuring and Publicly Displaying Domestic Electricity Consumption. Workshop on Energy Awareness and Conservation through Pervasive Applications (Pervasive 2010) (forthcoming).
The Lambent Shopping Trolley Handle and the Tidy Street project have shown that there are four key challenges when designing for behaviour change:
- increasing awareness of a behaviour
- motivating people to change
- facilitating change
- sustaining change
Salience and social norms can be effective behaviour change techniques that help address the first three challenges. However, the Tidy Street project suggests that over time their effectiveness can diminish and that the key challenge is finding ways to keep people motivated to change their behaviour.
P. W. Schultz, J. M. Nolan, R. B. Cialdini, N. J. Goldstein, and V. Griskevicius. The constructive, destructive, and reconstructive power of social norms. Psychological Science, 18(5):429–434, 2007.