Judgments rendered on objective scales, like weight and height, are generally considered to be free from contextual effects. New evidence suggests this may not be true.
Consider the following two questions:
1 – How ferocious is a badger on a 10-point scale?
2 – How much does a badger weigh?
Numeric judgments of a badger’s ferocity clearly depend on the animals with which a badger is being compared (which could range from a baby bunny to the xenomorph monster from the Aliens trilogy). It is well known that responses on such subjective scales are affected by the judgmental context, whether implicit or explicit. People assign badgers higher ferocity numbers when they first consider bunnies (which badgers eat) and lower numbers when they first consider crocodiles (which might well eat a badger).
By contrast, responses on objective scales are widely thought to be immune to contextual shifts in meaning. Nobody asked to estimate a badger’s weight would think of asking, “compared to what?” Many have, therefore, concluded that such responses are context free.
“We challenge this presumption,” write Shane Frederick of Yale University and Daniel Mochon of Tulane in a 2012 article for the Journal of Experimental Psychology. Frederick and Mochon argue for what they call a scale distortion theory of anchoring in which context does, in fact, affect objective numeric scales.
Their argument hinges on the idea that the perceived magnitude of a number can be influenced by other numeric values on the same scale. Seven-hundred pounds seems larger if compared with 20 pounds and seems smaller if compared with 5,000 pounds. If someone estimates the weight of a giraffe and nothing else, for example, 1,000 pounds might seem like a reasonable guess. If someone first estimates the weight of a relatively light animal, like a raccoon, then 1,000 pounds would be, comparatively, a very large number, and, thus, 700 pounds might seem like a more reasonable figure. “Objective scales,” argue Frederick and Mochon, “are susceptible to the same sort of contextual effects that affect subjective scales.”
In their first experiment, participants examined a list of 15 animals ordered by weight, from very light (mouse) to very heavy (elephant), and selected the one whose average adult weight was closest to 1,000 pounds. Half of the participants estimated the weight of a relatively light animal—an adult wolf—before making this judgment; the other half did not. Scale distortion theory posits that 1,000 pounds would seem larger for those in the wolf group, and the results adhered to this theory: the animals selected as representing 1,000 pounds were significantly larger for those who first considered a wolf. (A similar confirmation used 13 food items, listed from least to most caloric, with half of the participants first asked to guess the calorie count of an apple.) The giraffe experiment noted above was also conducted by Frederick and Mochon, with results as described.
Interestingly, this scale distortion had no appreciable effect on related estimates. Though weight estimates of a giraffe varied depending on whether people first considered a raccoon or blue whale, guesses about the height of a giraffe or how many lions it might feed were unaltered.
Related to this, Frederick and Mochon found that distortion only takes place when comparisons are made across the same scale. When participants were asked to guess the weight of a blue whale in pounds, subsequent estimates of a giraffe’s weight were markedly higher. However, if the first judgment was in tons, the second estimate (in pounds) was unaffected. “That judgmental effects are limited to the condition involving the identical scale suggests it is a scaling effect,” they write.
Scaling effects are not mere artifacts. Suppose, for instance, criminals received shorter sentences when a sentence rendered in a preceding case was very short. As Frederick and Mochon note, the victim would hardly take comfort from the news that the lighter sentence was just a scaling effect and not a reflection of the judge’s position on the severity of the crime. In the marketing world, their results suggest that evaluation order might affect how much money people actually spend. Consumers may pay more for a bottle of wine if they have just considered the price of a laptop and less if they’ve just considered the price of a pen.
“Brass weights and other physical standards can be safeguarded at the international bureau of weights and measures,” they conclude. “But the psychological meaning of 1,000 pounds or 1,000 calories is less easily protected.”