Pay attention! Many consumers believe 36 months is longer than 3 years

Feb 14, 2011

Consumers often have a distorted view when they compare information that involves numbers, according to a new study in the Journal of Consumer Research.

"As a consumer, would your preference for a dishwasher depend on whether its warranty level is expressed in months rather than years?" write authors Mario Pandelaere (Ghent University, Belgium), Barbara Briers (Tilburg University, the Netherlands), and Christophe Lembregts (Ghent University, Belgium).

To most consumers, the answer is "yes." The difference between an 84-month and a 108-month warranty looks bigger than the difference between a seven-year and a nine-year warranty, despite the fact that both differences are exactly the same.

"Qualitative information can usually be specified in alternative units," the authors write. "In many cases, however, the specific unit in which information is described is arbitrary. For instance, product quality ratings may be expressed on a scale from 0 to 10 or on a scale from 0 to 100," the authors write. "People typically fail to realize that the unit of quantitative information is arbitrary. They just focus on the number of scale units used to express a certain difference."

As a result, higher numbers seem to represent bigger quantities. This "unit effect" is the reason why consumers perceive a bigger difference between ratings 90 and 95 out of 100 than they do between a 9 or 9.5 out of 10.

In an additional study, the authors found that the unit effect can be used to encourage healthy food choices. In one experiment, participants exiting the lab were offered the choice between a complimentary apple or a Twix® bar. The energy content of these two choices was either expressed in Kilojoules (247 for the apple versus 1029 for the Twix®) or Kilocalories (59 for the apple versus 246 for the Twix®). "Participants more often chose the apple when the energy content was expressed in Kilojoules than in Kilocalories as the former difference (782 Kilojoules) looks much bigger in the latter one (187 Kilocalories).

However, the authors found that the effect was not replicated when people pay close attention to specific attribute information or when people are reminded of the arbitrary nature of the unit in which information is expressed.

Explore further: Why plants in the office make us more productive

More information: Mario Pandelaere, Barbara Briers, and Christophe Lembregts. "How to Make a 29% Increase Look Bigger: The Unit Effect in Option Comparisons." Journal of Consumer Research: August 2011 (published online February 1, 2011). More information: ejcr.org .

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User comments : 5

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Eikka
not rated yet Feb 14, 2011
Depends on how you conceptualize numbers. For me, everything around the number 100 is treated as if it was a percentage of something, so I automatically translate 84 vs. 108 into "roughly 20% difference" which isn't very much.

I would be more easily fooled by 7 and 9 years of warranty.
Eikka
not rated yet Feb 14, 2011
And equally, for me the difference between 9 and 9.5 seems more significant than the difference between 90 and 95 because the former is "nine and half" and half is a lot, whereas the latter is "roughly 5% more" which is just a little.

I would probably fall for the apple-twix trick as well though, since a figure close to a 1000 is easily divided and I can immediately see that the apple is roughly 1/4th the joules, whereas 59 vs 246 would on the first glance seem like the apple is only 1/5th the calories since there's the "only 5.99" effect that masks the fact that 4 x 60 is 240.

That's why I always round prices up to the nearest full unit when shopping, or add 1 to every 9 I see to more quickly grasp how much everything is.
Joe_S
not rated yet Feb 14, 2011
see this is is exactly what i'm talking about
paulthebassguy
5 / 5 (2) Feb 14, 2011
This research confirms once again that the general population is just dumb.
Moebius
not rated yet Feb 15, 2011
And I believe that not only is $9.99 less than $10.00, it's a LOT less.

However, the authors found that the effect was not replicated when people pay close attention to specific attribute information or when people are reminded of the arbitrary nature of the unit in which information is expressed.


So when they were told they are stupid they got smarter?