Noticing that there wasn’t an article about this concept on Wikipedia, I’ve written the following and donated it to start off an article. The GNU Free Documentation license applies. (Updated 2 June. 20 hours after its creation, the article is the number four hit for its title on Google UK!)
Attribute Substitution is a psychological process thought to underlie a number of cognitive biases and perceptual illusions. It occurs when an individual has to make a judgment (of a target attribute) that is computationally complex, and instead substitutes a more easily calculated heuristic attribute. This substitution is thought of as taking place in the automatic intuitive judgment system, rather than the more self-aware reflective system. This explains why biases are unconscious and persist even when the subject is made aware of them. It also explains why human judgments often fail to show regression toward the mean. Hence, when someone answers a difficult question, they may be answering a related but different question, without realising that a substitution has taken place.
In a 1974 paper, psychologists Amos Tversky and Daniel Kahneman had argued that a broad family of biases (systematic errors in judgment and decision) were explainable in terms of a few heuristics (information-processing shortcuts), including availability and representativeness. In a 2002 revision of the theory, Kahneman and Shane Frederick proposed attribute substitution as a process underlying these and other effects.
In 1975, psychologist Stanley Smith Stevens proposed that the strength of a stimulus (e.g. the brightness of a light, the severity of a crime) is encoded neurally in a way that is independent of modality. This idea was built on by Kahneman and Frederick in arguing that the target attribute and heuristic attribute could be very different in nature.
Kahneman and Frederick propose three conditions for attribute substitution:
- The target attribute is relatively inaccessible.Substitution is not expected to take place in answering factual questions that can be retrieved directly from memory (“What is your birthday?”) or about current experience (“Do you feel thirsty now?)
- An associated attribute is highly accessible.This might be because it is evaluated automatically in normal perception or because it has been primed. For example, someone who has been thinking about their love life and is then asked how happy they are might substitute how happy they are with their love life rather than other areas.
- The substitution is not detected and corrected by the reflective system.
For example, when asked “A bat and a ball together cost $1.10. The bat costs $1 more than the ball. How much does the ball cost?” many subjects incorrectly answer $0.10. An explanation in terms of attribute substitution is that, rather than work out the sum, subjects parse the sum of $1.10 into a large amount and a small amount, which is easy to do. Whether they feel that is the right answer will depend on whether they check the calculation with their reflective system.
The Beautiful-is-Familiar effect
Psychologist Benoît Monin reports a series of experiments in which subjects, looking at photographs of faces, have to judge whether they have seen those faces before. It is repeatedly found that attractive faces are more likely to be mistakenly labeled as familiar.  Monin interprets this result in terms of attribute substitution. The heuristic attribute in this case is a “warm glow”; a positive feeling towards someone that might either be due to their being familiar or being attractive.
When subjects are offered insurance against their own death in a terrorist attack while abroad, they are prepared to pay more for it than they would for insurance that covers death of any kind while abroad, even though the latter clearly includes the former. Kahneman suggests that the attribute of fear is being substituted for a calculation of the total risks of travel. Fear of terrorism is stronger than a general fear of dying on a foreign trip.
Stereotypes can be a source of heuristic attributes. In a face-to-face conversation with a stranger, judging their intelligence is more computationally complex than judging the colour of their skin. So if the subject has a stereotype about the relative intelligence of whites, blacks and Asians, that racial attribute might substitute for the more intangible attribute of intelligence. The pre-conscious, intuitive nature of attribute substitution explains how subjects can be influenced by the stereotype while thinking that they have made an honest, unbiased evaluation of the other person’s intelligence.
In optical illusions
Attribute substitution would also explain the persistence of some illusions. For example, when subjects judge the size of two figures in a perspective picture, their apparent sizes can be distorted by the 3D context, making a convincing optical illusion. The theory states that the three-dimensional size of the figure (which is accessible because it is automatically computed by the visual system) is substituted for its two-dimensional size on the page. Experienced painters and photographers are less susceptible to this illusion, because the two-dimensional size is more accessible to their perception.
2. Kahneman, Daniel; Shane Frederick (2002). “Representativeness Revisited: Attribute Substitution in Intuitive Judgment”. in Thomas Gilovich, Dale Griffin, Daniel Kahneman. Heuristics and Biases: The Psychology of Intuitive Judgment. Cambridge: Cambridge University Press. pp. 49-81.
3. Monin, Benoît; Daniel M. Oppenheimer (2005). “Correlated Averages vs. Averaged Correlations: Demonstrating the Warm Glow Heuristic Beyond Aggregation“. Social Cognition 23 (3): 257-278. ISSN 0278-016X
- Daniel Kahneman (December 8, 2002) Maps of Bounded Rationality: A Perspective on Intuitive Judgement and Choice (Nobel Prize lecture)
- Daniel Kahneman (2007) Short Course in Thinking about Thinking (Edge.org)