Consistency is contrary to nature, contrary to life. The only completely consistent people are the dead.

Aldous Huxley

Many people have bought cotton shopping bags to use in place of the plastic bags provided by stores. While we expect that the people who have bought these bags prefer to use them whenever they shop, I also expect that like myself, they frequently leave them behind in the house or car. The problem is not a lack of motivation to use the bags, but rather simply forgetting to bring them.

Numerous actions that promote sustainability are susceptible to the most human of traits: forgetting. Turning off computer equipment, turning down the thermostat in the evening, checking the air pressure in our tires and selecting products that have recycled content while shopping are just a few of the many actions that we are apt to forget to do. In some cases, innovations such as a programmable thermostat can free us from the burden of continually remembering to carry out an activity. Most repetitive actions, however, have no simple “technological fix.”

Fortunately, “prompts” are effective in reminding people to engage in sustainable behaviors. A prompt is a visual or auditory aid which reminds us to carry out an activity that we might otherwise forget. The purpose of a prompt is not to change attitudes or increase motivation, but simply to remind us to engage in an action that we are already predisposed to do.

Prompts and Sustainable Behavior

Prompts abound. Slogans, such as “Think Globally, Act Locally,” are, as Gardner and Stern suggest, designed to promote sustainable behaviors.1 Despite a prevalent belief that prompts such as this are effective in promoting sustainable behavior, non-explicit prompts ordinarily have little or no impact. Prompts that target specific behaviors can, however, have a substantial impact. Here are several examples:

  • In a water efficiency project in Perth, Australia the application of prompts to various household devices, such as taps, reduced water use by 23%.2 Simply providing households with an informational pamphlet encouraging reductions in water use had no impact, however. This study underscored the importance of presenting a prompt in close proximity to the behavior to be encouraged.
  • In a project in the Netherlands, providing a prompt over a waste receptacle that activated either personal or social norms regarding littering, resulted in a 50% reduction in litter.3
  • In a study with significant implications, the presence of lids which indicated which recyclables should go in which recycling containers increased beverage recycling by 34% and significantly reduced contamination.4
  • Jeffrey Smith and Russell Bennett have shown that prompts can be very effective in discouraging people from walking across lawns.5 At four separate locations, 79% of pedestrians were found to cut across a lawn rather than taking a slightly longer pathway. However, when a sign with the message, “Do not cut across the grass,” was placed at these four sites, lawn-walking decreased by 46%. Lawn-walking was reduced even further when a second sign was added that said “Cutting across the grass will save 10 seconds.” Indeed, when these two signs were present, lawn-walking was reduced to only 8%.
  • Prompts by themselves have not been found to be effective in encouraging pet owners to pick up after their dogs. However, when signs were combined with modeling of the desired behavior, 80% of dog owners picked up after their pet.6
  • Litter receptacles serve as a visual prompt for the proper disposal of garbage. Simply making a litter receptacle more visually interesting was found to double the amount of litter deposited in one study and increase it by 61% in another.7,8
  • Retrofitting older buildings is the most effective way to reduce their energy use, but for many organizations the cost of a retrofit is prohibitive.9 Simple lifestyle changes can, however, have a significant impact upon energy use, often with no capital expense. One such example involved encouraging university faculty to drop and tilt their blinds when they left their offices at the end of the day to reduce night-time heat loss during the winter. Baseline data was collected by cleaning staff who recorded whether blinds were dropped and tilted correctly (concave surface of the blind tilted into the room to deflect heat back into the room). Faculty were encouraged to drop-and-tilt their blinds through a general written request from the university president and by having the cleaning staff leave a reminder on the desk of faculty who forgot to drop-and-tilt their blinds. These two simple methods increased the percentage of faculty who adjusted their blinds from less than 10% to roughly two-thirds.
  • Compared to baseline, the introduction of more conveniently located recycling containers and the use of prompts increased the amount of newspaper recycled in three apartment complexes from 50% to 100%.10
  • Following the introduction of verbal and visual prompts in a high school cafateria, littering was reduced by over 350%.11
  • Prompts have also been shown to have a substantial impact upon paper recycling.12 In one department at Florida State University, a prompt that read “Recyclable Materials” was placed directly above a recycling container. The prompt indicated the types of paper to be recycled, while another prompt over the trash receptacle read “No Paper Products.” The addition of these two simple prompts increased the percentage of fine paper captured by 54%, while in another department the same procedure increased the capture rate by 29%.

These and other studies support the notion that to be effective, a prompt should be delivered as close in space and time as possible to the target behavior. Accordingly, place prompts to turn off lights on or beside the light switch by the exit. Similarly, prompts to purchase products that contain recycled content should be on the store shelf directly in front of the product.

Prompts and Source Reduction

Several initiatives to encourage source reduction are demonstrating just how effective prompts can be in promoting sustainable behavior.

The Minnesota Office of Waste Management has designed a program entitled SMART (Saving Money And Reducing Trash) that provides communities with various educational materials for shoppers. One element of this program is the “shelf talker.” Shelf talkers are prompts that identify products that reduce waste and save money. Similarly, the Central States Education Center in Champaign, Illinois uses posters, flyers and shelf labels to indicate products that are environmentally friendly.13 This program identifies items that either are recyclable locally, have less packaging, or are “safer-earth” products (e.g., non-toxic cleaners). Affixing 700 long-term labels throughout a store takes several hours, considerably less time than it takes to adjust the 17,000 price labels that, on average, are changed weekly. Analysis of supermarket store inventory suggests that the use of these prompts has shifted purchases to recyclable containers. The impact upon the purchase of “least-waste packages” and “safer earth products” has not yet been determined.14

In Seattle, Washington, a “Get in the Loop, Buy Recycled” campaign has been operating for several years.15 Like the other initiatives, this program utilized shelf talkers that identify products with recycled content. The program was advertised through television, radio and newspaper advertisements by both the King County Commission for Marketing Recyclable Materials and participating retailers. In the year that it was initially launched, 850 retailers in western Washington state participated. Relative to the month preceding the initial launch of the campaign, sales of recycled-content products increased nearly 30%.16 Sales of specific product categories have shown even more dramatic increases. For example, sales of recycled-content paper products have increased by 74%.

Building Prompts into Your Program

Prompts can be effective for encouraging both one-time and repetitive behaviors that promote sustainability. One-time behaviors, as the name suggests, refer to actions that individuals engage in only once, but that result in an ongoing positive environmental impact (e.g., installing a clock thermostat, connecting a low-flow shower head). Because these behaviors only have to be engaged in once, they are often easier to influence than repetitive behaviors, where an individual has to engage in an action repeatedly for there to be a significant environmental benefit (e.g., composting, source reduction). Given the difficulty of making lifestyle changes that promote sustainability, prompts may be of particular use in establishing and maintaining repetitive behaviors that favor sustainability.

A Checklist for Using Prompts

In considering using prompts, follow these guidelines.

  • Make the prompt noticeable.
  • The prompt should be self-explanatory. Through graphics and/or text the prompt should explain simply what the person is to do (e.g., turn off the lights).
  • The prompt should be presented as close in time and space as possible to the targeted behavior (e.g., place a prompt to turn off lights directly on a light switch; place a prompt to purchase a product with recycled content directly below the product).
  • Use prompts to encourage people to engage in positive behaviors rather than to avoid environmentally harmful actions.

Below are several examples of how prompts can be used to foster sustainable behavior.

Examples: Using Prompts to Foster Sustainable Behavior
Agriculture & Conservation
  • Provide farmers with calendars that prompt conservation actions. A calendar produced by Ducks Unlimited that did this significantly affected the behavior of farmers.
  • Affix decals directly to light switches to prompt that lights be turned off when rooms are vacant. Do the same with thermostats to encourage that temperatures be turned up or down when a home will be vacant.
  • Affix decals to dishwashers and washing machines encouraging that they only be used when there is a full load and with cold water.
  • Affix decals to appliances which indicate the relative energy efficiency of the appliance. This is presently done for major appliances in Canada.
  • Use signs to encourage drivers to turn off their engines while parked in locations where drivers frequently wait, such as schools, train stations, and loading docks.
  • Affix removable decals to the windows of new cars prompting drivers to turn off their engines while parked.
  • Use prompts along with commitments to encourage car owners to have their car engines regularly tuned-up and their tires properly inflated.
Waste & Pollution
  • Use prompts at the point of sale to promote source reduction.
  • Distribute grocery list pads that remind shoppers every time they look at their grocery list to shop for products that have recycled content, are recylable, or have least-waste packaging.
  • Place signs at the entrances to supermarkets reminding shoppers to bring their reusable shopping bags into the store. Also, distribute car window stickers with the purchase of reusable shopping bags; the stickers can be put on the window next to the car lock to remind people to bring their reusable bags into the store.
  • Have check-out clerks ask consumers if they have brought bags with them.
  • Affix decals to potentially hazardous household products during home assessments that indicate vividly that the product must be disposed of properly. The decal should contain information on where to dispose of hazardous waste and a contact number.
  • Attach a decal to the side of recycling containers indicating what can be recycled.
  • To encourage that lawns are watered only when necessary, ask homeowners for permission to place a tag on the outside water faucet.
  • Arrange with local retailers to attach decals to lawnmowers that encourage householders to raise the level of the lawnmower. Additionally, this decal can encourage that the grass clippings be left on the lawn (mulched) as a natural nutrient.
  • Have homeowners place an empty tuna can in the garden (to measure adequate watering). When the can is filled with water the garden or lawn has been adequately watered.

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