Why the framing of transport information matters

Research in numerous fields has shown that people’s decisions are influenced by the way in which problems are stated. In the field of transport, this implies, for instance, that the framing of information on journey planners can affect the route and the travel mode chosen. If we want people to make more informed mobility decisions, it is essential that information on the costs and benefits of each option is expressed in terms that they can understand without additional intellectual effort, and that they can translate immediately in terms that are directly relevant for them.

• People’s decisions are influenced by the way in which problems are stated

• People should receive information expressed in terms that are directly relevant for them

• Information on travel options should be expressed in terms that people can understand effortlessly

• The framing of information on journey planners can affect the route and the travel mode

When economists discuss how people make decisions on the transport modes they will take, or the routes they will follow to reach a given destination, they usually assume that people only consider the contents of the information which is provided. For instance, it should not matter whether your journey planner tells you that Route A is 10 kilometres longer than Route B, or that Route B is 10 kilometres shorter than Route A. It seems like simple common sense that people would act the same in both settings.

Except that they don’t. Research in numerous fields has shown that people’s decisions are affected by elements that are, objectively speaking, irrelevant. For instance, in a medical context, Wilson et al. (1987) have conducted psychological experiments where people were confronted with the decision whether a hypothetical patient described as their ‘father’ should return from the intensive care unit to the regular floor.

It turns out that people were more willing to endorse this return if his chances of surviving were presented as 90% than when told that his chances of dying were 10%.

Choices thus depend, in part, on the way in which problems are stated (Thaler & Sunstein, 2008).

And this has direct implications for transport policy.

Some journey planners currently do not just provide information on travel distance and estimated travel time, but also on the environmental implications of travel choice. Suppose, for the sake of concreteness, that journey planners would not just report the different travel options, but would also compare the CO2 emitted in one option with emissions for two other options. There are at least two ways to frame CO2 emissions: as ‘losses’ compared to the option with the lowest emissions or as ‘gains’ compared to the option with the highest emissions.

Avineri and Waygood (2013) have conducted an experiment where people were confronted with the CO2 emissions of three travel options for a five mile trip: a bicycle, a car occupied with four passengers, or a single occupancy four-wheel-drive vehicle. The results obtained by Avineri and Waygood confirmed that people are more likely to label the alternative options as “very different” if the information emphasises the possibility to reduce environmental damage compared to the worst travel option.

The framing of the environmental implications of travel choices is thus likely to influence these choices, at least if people do actually care about the environmental impacts of their travel choices. Avineri and Waygood themselves emphasize that information provision in itself is unlikely to result in substantial behavioural changes. However, environmental information can be embedded within broader packages of incentives for sustainable travel behaviour.

Another example is the ‘miles per gallon’ illusion: in the US, fuel efficiency is expressed as miles per gallon (rather than as litres per 100 km).

Larrick and Soll (2008) find that people systematically misunderstand the concept of miles per gallon (MPG), and tend to undervalue small improvements on highly inefficient vehicles.

Let us follow the example given by Larrick and Soll, and consider a car that drives 10,000 miles. A car with 12 MPG consumes 833 gallons over this distance, while a car with 14 MPG consumes 714 gallons. This corresponds to a total fuel saving of approximately 120 gallons. Now compare this with the gain obtained when a car with 28 MPG is replaced by a car with 30 MPG: the total savings is barely 23 gallons (357 gallons – 333 gallons). Clearly, the greatest environmental benefit is to be obtained by focusing in replacing the gas guzzlers, although the change in MPG is the same for both cases.

If the standard is expressed as “gallons per mile” instead, consumers understand better how much fuel they are using on a given car trip or in a given year.

Of course, in terms of direct policy implication, these findings are only relevant for countries such as the US. However, they do point to a broader lesson: if we want people to make more informed decisions, it is essential that this information is expressed in terms that they can understand without additional intellectual effort, and that they can translate immediately in terms that are directly relevant for them. In this case, the total amount of fuel one consumes over a year is more directly relevant than the distance one can cover with a given amount of fuel.

  • Avineri, E. and E.O.D. Waygood (2013), Applying valence framing to enhance the effect of information on transport-related carbon dioxide emissions, Transportation Research A 48, 31–38.
  • Larrick, R.P. and J.B. Soll (2008), The MPG Illusion, Science 30, 1593-1594.
  • Thaler, R.H. and C.R. Sunstein (2008), Nudge, Improving Decisions About Health, Wealth, and Happiness, Yale University Press.
  • Wilson, D. K., Kaplan, R. M., & Schneiderman, L. J. (1987). Framing of decisions and selections of alternatives in health care. Social Behaviour, 2, 51–59.

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