Psychology 458/558
Judgment and Decision Making
Prof. Bertram Malle
Fall 1995


Lecture 14: Nov 16
Explanation

1. What is an explanation?

An explanation is the answer to a why X? question (where X is some event or state of affairs); it answers this question by providing clarifying information in the form of facts, processes, mechanisms, or principles in light of which X becomes understandable to the questioner.

Good explanations are tailored to the questioner and they contrast the given explanation with alternative explanations (Mills' method of difference, Hilton & Slugoski, 1986).

Predictions provide beliefs about outcomes (typically future states), they are sometimes verifiable, and they don't require knowledge of a causal mechanism. Explanations, by contrast, provide understanding, they are rarely directly verifiable, but they can be evaluated as relatively convincing and clear. Predictions are often based on explanations; conversely, an explanation can be tested by testing a prediction derived from it. Explanations are in some sense easier to produce (in hindsight, by fitting ideas to the data) but harder to prove--prototypical examples of this asymmetry can be found in psychoanalysis and evolutionary psychology.

2. Bases of explanations

Explanations are given using a variety of constructs: theories, models, stereotypes, dispositions, processes/mechanisms, event chains (scripts). Where do these constructs come from?

Classical conditioning. Humans are extremely good at representing co-occurrences of events. This conditioning process is the core of associative learning and memory. But this ability makes people somewhat biased in the detection of true correlations. The bias is most crucial when the base rates of the events in question is extreme and/or asymmetric. A pattern of data like the one below leads to strong associative bonds for the co-occurrence of A and B, even though A and B are not correlated with each other (they are just both frequently present).

			 Event A 
Event B present absent
present 16 4
absent 4 1
Many problems in human judgment discussed in previous lectures are based on or related to this "trap of conditioning"--availability, neglect of base rates, neglect of Bayes' theorem, SDT biases. But the recognition of correlation /covariation can be very helpful for finding a causal explanation for an event: Kelley's ANOVA model of attribution is built on the assumption that people look for covariation information (see Plous).

Plausibility. As discussed under the representativeness heuristic, the plausibility or stereotypical fit of an explanation is often mistaken as evidence for its truth. Examples of the power of plausibility abound in the literature (e.g., Rorschach ink blots, Draw-a-man test), and the most recent false accusations of Islamic groups after the Oklahoma City bombing attack add a sad one to the list. Plausibility can arise from semantic or conditioned associations, from persuasive arguments, emotional appeals, vivid experiences, wishful thinking, etc.

Normality. Kahneman and Miller (1986) propose a theory of norms that describes how perceptions of objects and events recruit "norms"--i.e., aggregates of past experiences, knowledge, and expectations, which provide standards to judge the object or event at hand.

Norms are often standards of comparison. Which standard you have in mind when making a judgment is crucial: "I am assertive" can mean "assertive relative to other people" or "assertive in most situations I choose to enter." McGill (1989) showed that people's explanations for a simple decision such as choosing psychology as one's major differ depending on the standard of comparison (or norm) that is being recruited. Compare "Why did you choose to major in psychology?" with "Why did you choose to major in psychology?"

In general, explanations of events are likely to focus on "mutable elements" of the event--i.e., aspects that can easily be mentally undone ("if only..."). This process of undoing is called "counter-factual reasoning." Elements are more likely to be mutable if they are (a) exceptions to a rule or (b) deviations from an ideal. Emotions such as regret or anger also focus more often on mutable events.

The framework of norms can be fruitfully applied to better understand several phenomena in judgment and decision making, such as anchoring and adjustment, non-regressive prediction, belief perseveration, base-rate neglect, determinants of regret, and the conjunction fallacy.

Hilton (1990) points out that discrepancies from norms evoke a why question that contains the norm as a contrast cases (e.g., "Why X rather than non-X?", "Why X rather than Y?"). Explanations themselves, understood as answers to questions and thus most often uttered in conversation, must fill the questioner's knowledge gap in light of those norms. Hilton describes in detail the communicative rules (à la Grice) that speakers follow when providing explanations, and he applies his conversational framework to several past research findings (just like Schwarz, 1994, did in a paper assigned last week).

3. The Study of Behavior Explanation

Normative attribution models. Jones & Davis (1965) analyzed rules that people use (or should use) when inferring dispositions from other people's behavior (so called "correspondent inferences"). Among these rules are the principle of noncommon effects (to infer a person's disposition, you must look at those aspects of the chosen behavior that are different from other possible behaviors) and the principle of desirable effects (when inferring a person's disposition, you can be more confident if the person behaves in ways that do not bring about generally desirable effects).

Kelley (1967, 1972) formulated more extensive rules in his "ANOVA model." People should explain a given behavior by reference to other pieces of information about other people, other stimuli, and other contexts. The pattern of covariation across these three factors provides the normative basis for an explanation. Topics studied in the wake of this model include the fundamental attribution error, the actor-observer asymmetry, salience effects, ego-biases, and attributional styles in relationships, depression, and achievement situations.

As a model of how people do in fact explain behavior, Kelley's model has major weaknesses, among them the sole focus on an individual person's reasoning (rather than the communicative context of explanations) and the neglect of people's own concept of human behavior. The following two descriptive models try to correct these weaknesses.

A descriptive model of behavior explanations. One of the major weaknesses of classic attribution theory is its assumption that people explain all behavior alike--namely by way of person causes and situation causes. But this person-situation dichotomy of causal explanations fits well only for unintentional behaviors; intentional behaviors, by contrast, are explained by reason explanations, which assume the actor's conscious choice in behaving that particular way and cite the actor's reasons for that choice. Data from my own research show that