FTT originated as an explanation of puzzling results.1-4
In experiments that spanned many of the major paradigms in developmental, experimental, and judgment and decision-making psychology, memory capacity for verbatim background facts in problems, such as numerical information, did not affect reasoning accuracy. Judgment and decision making relied preferentially on gist
representations of information (e.g., about risk), as opposed to verbatim representations. Gist
are defined much as they are in everyday parlance, except that verbatim
applies to more than verbal information but also to graphs, numbers, pictures, and any other form of information. Thus, a gist representation is vague and qualitative; it captures the bottom-line meaning
of information, and it is a subjective interpretation of information based on emotion, education, culture, experience, worldview, and level of development. A verbatim representation, in contrast, is precise and quantitative, and it captures the exact surface form
of information (i.e., it is literal).
Consider a 49-year-old woman attempting to understand her risk for breast cancer. Suppose that she comes across the Breast Cancer Risk Estimation Tool that is available on the National Cancer Institute Web site and answers the 9 questions found there (http://www.cancer.gov/bcrisktool/
). Suppose further that, according to this tool, her estimated lifetime risk is 22.2% of developing invasive breast cancer.5
The verbatim level of risk given by this tool is “22.2%.” However, the interpretation of that risk, the gist, could range from “low” to “high” risk; the risk is low in that it is unlikely to occur (less than 50%), but the risk is high relative to an average risk of 11.3% for a 49-year-old woman (also generated by the tool). The gist of the risk that is extracted from an estimate such as 22.2% depends on contextual and individual factors, including a person's level of numeracy (i.e., ability to understand numbers).6
The gist representation is the answer to the question “What does 22.2% mean?
” to that individual.
summarizes evidence from experiments, mathematical models, neuroimaging, and other methods that support the conclusion that people extract separate gist and verbatim memory representations from many types of information: words, numbers, literal sentences, metaphors, pictures, graphs, narratives, and events. presents definitions and examples of judgment and decision-making effects (many demonstrated in the context of health communication and medical decision making) explained by FTT.7-13
This evidence establishes that the theory can accommodate a wide array of known effects, lending credence to its assumptions and mechanisms.
Types of Evidence for Fuzzy Trace Theory
Definitions and Examples of Some of the Effects in Judgment and Decision Research Explained by Fuzzy Trace Theory
More important, however, the theory has led to new discoveries, such as the memory independence effect (that reasoning accuracy is independent of memory accuracy);14
that reliance on gist-based intuition increases with development;15,16
that such intuition reduces unhealthy risk taking;17,18
that disentangling and making set relations transparent reduces errors in probability judgment such as base rate neglect;8,19
and that reliance on verbatim memory can impair reasoning performance.2
As detailed in the next section, FTT has also been extended to how laypersons (e.g., patients) and health care providers (e.g., physicians) understand, process, and apply representations of health-relevant information in a variety of contexts, including HIV prevention,7,18
and cancer prevention and control.23
Taken together, these studies show that gist and verbatim representations are extracted roughly in parallel and independently and that people prefer to operate on the crudest gist representation that they can to make judgments or decisions. What this means is that our hypothetical 49-year-old woman encodes and stores the verbatim number “22.2%” along with separate representations of the gist of that number to her, such as “That's really bad; my risk is high.” Note that gist includes the emotional meaning, or affective interpretation, of the information.24,25
As has so often been demonstrated, people may pass a knowledge test about the literal content of risk communication messages (they remember the facts they have been taught), but their risk behavior is not necessarily affected by those messages.26,27
According to FTT, judgments and decisions, and, consequently, behavior are affected by the gist that people understand, rather than the verbatim facts they are presented with.
FTT is referred to as a dual-processes theory, but dual gist and verbatim representations are endpoints of what is, in reality, a continuum of representations. (For a discussion of distinctions between FTT and standard dual-process accounts, see Reyna and Brainerd10
). In particular, people extract multiple levels or “hierarchies” of gist from information, although they might only use one representation at a time in reasoning or decision making. These hierarchies of gist can be thought of as analogous to scales of measurement, with nominal or categorical being the simplest distinction, then ordinal, and then finer grained distinctions, such as interval or ratio level. For example, our hypothetical 49-year-old woman might encode “my risk is high,” “I am going to get cancer like my sister did,” “my risk is higher than average,” “0.2 means that this estimate is exact,” “22.2% is about 1 in 5,” and so on.
The preference to operate on the crudest gist, the fuzzy-processing preference, increases with experience or expertise. For example, given a patient who presented in the emergency room with nontraumatic chest pain, experienced physicians homed in on the key dimension of imminent risk of myocardial infarction (MI), whereas less experienced physicians considered more dimensions.20
Similarly, experienced physicians focused on change in size over time of pigmented skin lesions, whereas less experienced physicians considered multiple dimensions, such as pigmentation and size.28
“Garden-path” thinking can occur in experienced reasoners that is sometimes fallacious because new instances do not always fit old experience. The quality of categorical thinking, then, is a function of the level of understanding of the thinker (see Reyna and Adam7
and Reyna and others9
for empirical methods for judging whether thinking is advanced). Gist-based thinking is not simply the retrieval of instances experienced in the past but instead is the distillation of the meaning
of past experiences into an intuitive, bottom-line interpretation (that is then recognized in and applied to current instances). It is not experience per se that is important but what is understood or learned from past experience that can be applied to recognizing similar future instances.*
A mental representation, whether gist or verbatim, does not determine judgments and decisions by itself, however. After information is represented, people retrieve their values, principles, and knowledge and apply them to the representation.9
People can retrieve reasoning principles that are then applied to representations to derive judgments and decisions, or they can retrieve factual knowledge to further interpret or elaborate on representations. For example, when a woman infers that “I am going to get cancer like my sister did,” she has retrieved knowledge about her sister from memory (e.g., “I am like my sister and my sister got cancer”) and applied that to the interpretation of 22.2%. Similarly, inferring that “my risk is higher than average” requires knowledge of some kind about “average risk” and comparing 22.2% to that average. A woman who interprets her risk as high because of a family history or genetic mutation may then decide to have a prophylactic mastectomy because she has retrieved the value “better to avoid risk,” in this instance, of breast cancer. A woman might have competing values, such as appearance (avoiding disfigurement), but the priority
of values in long-term memory and the cuing
of values in the episodic context jointly determine their accessibility at a given point in time (i.e., the relative importance of the value and whether it is cued in context both determine how readily it comes to mind). The latter effect of contextual cuing contributes substantially to variability in judgments and decisions, and its effect is generally underestimated. Even health care professionals can fail to retrieve highly overlearned knowledge without retrieval cues in the environment.29,30
presents examples of gist representations and retrieved values or principles in medical decision making and health. These representations are the bottom line or culmination of what might have been a far more detailed and elaborate thought process; therefore, they do not represent everything that a person knows about, for example, chemotherapy or screening, but they are the kinds of intuitive representations that guide decision making. For instance, in a sample of 33 adults offered a variety of alternatives, 91% endorsed the gist of screening when asymptomatic as a choice between feeling okay (without screening) and taking a chance on feeling okay (a negative test result) or not feeling okay (a positive test result). Because feeling okay is better than not feeling okay (a value), this gist clearly discourages screening (which is the only option that has not feeling okay as a possible outcome).
Examples of Gist Representations and Retrieved Values Used in Medical Decision Making and Health
As is apparent from the examples in , the gist is only as good as the level of understanding of the decision maker. Reyna and Adam7
reported that the gist of sexual transmission of disease as “exchange of bodily fluids” was associated with overestimation of the effectiveness of condoms, even among physicians, because this prototypic gist does not encompass infections, such as human papilloma virus, that are also transmitted skin to skin. The gist of chemotherapy as poison, although widespread, has similar shortcomings, motivating many to search for “healthy” alternatives with lower or unproven efficacy compared with chemotherapy. The gist of surgery depicted in —namely, as a technique for removing something bad from the body—explains why surgery would be unduly favored over equally effective medical approaches to cancer (e.g., 60% chose surgery for prostate cancer according to the National Prostate Cancer Coalition's annual Men's Health Survey, released 6 June 2006).31
Research has investigated how stereotypes reflect the gist of social categories and thus conform to predictions of FTT; for example, stereotypes show developmental trends that are similar to other kinds of gist-based thinking. Diseases, such as cancer, and therapies, such as surgery or chemotherapy, are also subject to stereotypes, which are inaccurate gist representations of the essence or bottom line of the category. As indicates, these stereotyped representations, in concert with retrieved values, sometimes lead medical decisions away from efficacious treatments and health-promoting behaviors.
Although the aforementioned representational and retrieval assumptions are central to FTT, concepts such as processing interference and inhibition have also played a part from the outset.32,33
Processing interference (often caused by nested or overlapping classes, as in probability judgments in which the target class is included in both the numerator and the denominator) rather than memory load explains many examples of human errors and fallacies. For example, consider a diagnostic test that has an 80% accuracy rate (80% positive when disease is present and 80% negative when disease is absent). Given a 10% base rate (or prevalence) of disease, if the test result is positive, is the likelihood of disease closer to 30% or 70%? In this example, the classes correspond to instances of different test results and instances of disease or no disease, which overlap with one another (e.g., having a positive test result with disease v. having a positive test result with no disease, etc.). Overlapping classes create confusion about what is being referred to and interfere with thinking coherently about probabilities.10,19,13,34
Even experienced physicians perform poorly in this simple forced-choice version of a base rate neglect task, so named because respondents fail to adjust sufficiently for the base rate. In one study, for example, 82 physicians chose the correct response only 32% of the time, significantly below a chance level performance of 50%.7,12
Studies have shown that poor performance in this task is not due to a lack of conceptual understanding of probability.8,35
Interference among overlapping classes is the key. People become confused about which classes are referred to (present for all ratio concepts, including probability): whether it is the ratio of people with positive test results to those who have disease or the ratio of people with disease to those who have positive test results. As summarized by Reyna and Brainerd, “Class-inclusion reasoning, probability judgment, risk assessment, and many other tasks, such as conditional probability, conjunction fallacy, and various deductive reasoning tasks, are subject to what has been called inclusion illusions. ... [8,10,13,34
] Inclusion illusions occur because part-whole relationships are difficult to process.”2(p34)
Processing can be simplified and interference reduced by providing a notational system in which elements of parts and of wholes are distinctly represented, such as Venn diagrams, used to represent subsets and more inclusive sets using a system of overlapping circles.8,36
In summary, the published literature has focused on errors in understanding messages about health-related risks and on biases in medical decision making; FTT can explain the processing origins of many of these errors and biases. These origins have to do, in no small part, with the difficulties people have in translating numbers (and other health-related information) into meaningful representations or gist, with reliably retrieving and implementing their values and knowledge, and with inherent complexities involved in processing ratio concepts, such as probabilities, among other factors.37,38
The meaning of health-relevant information is seldom self-evident, and even health professionals have difficulty retrieving knowledge and processing nested or overlapping classes involved in probability judgments.10,23,29