Evaluability
The evaluability principle explains how the precision and evaluability of attributes influence judgments, particularly in joint versus separate evaluations. Attributes that are hard to evaluate alone become more impactful when compared directly.
THE IDEA
EVALUABILITY
Affective impressions influence judgments and decisions. These impressions vary both in whether they are favorable or unfavorable and in how precisely they are held.
We refer to the distributional qualities of affective impressions and responses as affective mappings. Consider, for example, some questions posed by Mellers et al. (1992): “How much would you like a potential roommate if all you knew about her was that she was said to be intelligent?” Or, “Suppose, instead, all you knew about her was that she was said to be obnoxious?” Intelligence is a favorable trait but it is not very diagnostic (e.g., meaningful) for likeableness, hence its affective map is rather diffuse. In contrast, obnoxiousness will likely produce a more precise and more negative impression.
How much would you like a roommate said to be both intelligent and obnoxious? Anderson (1981) has shown that the integration of multiple pieces of information into an impression of this sort can be described well by a weighted average model where separate weights are given to intelligence and obnoxiousness, respectively. Mellers et al. (1992) further showed that the weights in such integrative tasks are inversely proportional to the variance of the impressions. Thus we would expect the impression produced by the combination of these two traits to be closer to the impression formed by obnoxiousness alone, reflecting greater weight given to obnoxiousness due to its smaller variance (more precise affective mapping). The meaning of a stimulus image appears to be reflected in the precision of the affective feelings associated with that image. More precise affective impressions reflect more precise meanings and carry more weight in impression formation, judgment, and decision making.
Hsee (1996a, 1996b, 1998) developed the notion of evaluability to describe the interplay between the precision of an affective impression and its meaning or importance for judgment and decision making. Evaluability is illustrated by an experiment in which Hsee asked people to assume they were music majors looking for a used music dictionary. In a joint-evaluation condition, participants were shown two dictionaries, A and B (Table 23.3), and asked how much they would be willing to pay for each. The referenced table is not reproduced here. Willingness-to-pay was far higher for Dictionary B, presumably because of its greater number of entries. However, when one group of participants evaluated only A and another group evaluated only B, the mean willingness to pay was much higher for Dictionary A. Hsee explains this reversal by means of the evaluability principle. He argues that, without a direct comparison, the number of entries is hard to evaluate, because the evaluator does not have a precise notion of how good or how bad 10,000 (or 20,000) entries is. However, the defects attribute is evaluable in the sense that it translates easily into a precise good/bad response and thus it carries more weight in the independent evaluation. Most people find a defective dictionary unattractive and a like-new one attractive. Under joint evaluation, the buyer can see that B is far superior on the more important attribute, number of entries. Thus number of entries becomes evaluable through the comparison process.
When to use it
Comparing job offers in an unfamiliar field: use market benchmarks to interpret salary figures that mean little in isolation.
Deciding on a used car: without comparison, a car's mileage may be hard to evaluate, but a worn steering wheel (defect) is easily evaluated negatively.
Comparing restaurant menus: ask which attributes become easier to judge side by side, without assuming that a larger number of dishes means a better meal.
FROM THEORY TO EVERYDAY LIFE
In practice
Roommate Impression Formation
Mellers et al. (1992) asked participants how much they would like a roommate described as 'intelligent' versus 'obnoxious'. Intelligence produced a diffuse affective impression, while obnoxiousness produced a precise negative impression. When both traits were combined, the overall impression was closer to obnoxiousness due to its smaller variance.
Music Dictionary Valuation Experiment
Hsee (1996a, 1996b, 1998) presented participants with two dictionaries: Dictionary A had 10,000 entries but a like-new condition; Dictionary B had 20,000 entries but a torn cover. In joint evaluation, participants were willing to pay more for B (higher number of entries). In separate evaluation, participants were willing to pay more for A (undamaged). The reversal is explained by the evaluability principle: number of entries is hard to evaluate alone, while defects are easily evaluable.
A MOMENT TO REFLECT
Put it to work.
Think of a time you made a decision between two options. How did the availability of a direct comparison affect which attributes you weighted more heavily?
When evaluating a single product, what attributes are normally 'evaluable' and which are not? How can you make the latter more meaningful?
How might marketers use the evaluability principle to influence consumer choices in separate vs. joint evaluation contexts?
References
- Mellers et al. (1992) — Mellers, B. A., Schwartz, A., Ho, K., & Ritov, I. (1992)
- Anderson (1981) — Anderson, N. H. (1981)
- Hsee (1996a) — Hsee, C. K. (1996)
- Hsee (1996b) — Hsee, C. K. (1996)
- Hsee (1998) — Hsee, C. K. (1998)
CONTINUE THE CONVERSATION
Source texts
- Heuristics and Biases The Psychology of Intuitive Judgment (Thomas Gilovich, Dale Griffin, Daniel Kahneman)