Biomedical subjects

Craig R M McKenzie

Publications and source records attributed to Craig R M McKenzie.

10 recordsLinked to original sources

PubMed2006

A Bayesian view of covariation assessment.

When participants assess the relationship between two variables, each with levels of presence and absence, the two most robust phenomena are that: (a) observing the joint presence of the variables has the largest impact on judgment and observing joint absence has the smallest impact, and (b) participants' prior beliefs about the variables' relationship influence judgment. Both phenomena represent departures from the traditional normative model (the phi coefficient or related measures) and have therefore been interpreted as systematic errors. However, both phenomena are consistent with a Bayesian approach to the task. From a Bayesian perspective: (a) joint presence is normatively more informative than joint absence if the presence of variables is rarer than their absence, and (b) failing to incorporate prior beliefs is a normative error. Empirical evidence is reported showing that joint absence is seen as more informative than joint presence when it is clear that absence of the variables, rather than their presence, is rare.

Analysis of Variance↗

PubMed2006

Recommendations implicit in policy defaults.

Should people be considered organ donors after their death unless they request not to be, or should they not be considered donors unless they request to be? Because people tend to stay with the default in a variety of domains, policymakers' choice of default has large and often important effects. In the United States, where the organ-donation policy default is "not a donor," about 5,000 people die every year because there are too few donors. Four experiments examined two domains-being an organ donor and saving for retirement-where default effects occur and have important implications. The results indicate that default effects occur in part because policymakers' attitudes can be revealed through their choice of default, and people perceive the default as indicating the recommended course of action. Policymakers need to be aware of the implicit messages conveyed by their choice of default.

Choice Behavior↗

PubMed2006

Increased sensitivity to differentially diagnostic answers using familiar materials: implications for confirmation bias.

Researchers have recently pointed out that neither biased testing nor biased evaluation of hypotheses necessitates confirmation bias--defined here as systematic overconfidence in a focal hypothesis--but certain testing/evaluation combinations do. One such combination is (1) a tendency to ask about features that are either very likely or very unlikely under the focal hypothesis (extremity bias) and (2) a tendency to treat confirming and disconfirming answers as more similar in terms of their diagnosticity (or informativeness) than they really are. However, in previous research showing the second tendency, materials that are highly abstract and unfamiliar have been used. Two experiments demonstrated that using familiar materials led participants to distinguish much better between the differential diagnosticity of confirming and disconfirming answers. The conditions under which confirmation bias is a serious concern might be quite limited.

Diagnosis↗

PubMed2005

Information leakage from logically equivalent frames.

Framing effects are said to occur when equivalent frames lead to different choices. However, the equivalence in question has been incompletely conceptualized. In a new normative analysis of framing effects, we complete the conceptualization by introducing the notion of information equivalence. Information equivalence obtains when no choice-relevant inferences can be drawn from the speaker's choice of frame. We show that, to support the normative implications traditionally attributed to framing effects, frames must be equivalent in this sense. We also present new evidence for McKenzie and Nelson's (2003) reference point hypothesis, which posits a tendency to cast descriptions in terms of what has increased relative to the reference point. This leakage of information about relative state violates information equivalence, and gives rise to a normative account of the most robust finding in the attribute framing literature - the valence-consistency of preference shifts. We argue that, more generally, valenced descriptions leak information about perceived valence. Such "implicit recommendations" may generalize the reference point explanation of the valence-consistent shift. Normative and psychological implications of the information leakage framework are discussed.

Choice Behavior↗

PubMed2005

Underestimating the duration of future events: memory incorrectly used or memory bias?

People frequently underestimate how long it will take them to complete a task. The prevailing view is that during the prediction process, people incorrectly use their memories of how long similar tasks have taken in the past because they take an overly optimistic outlook. A variety of evidence is reviewed in this article that points to a different, although not mutually exclusive, explanation: People base predictions of future duration on their memories of how long past events have taken, but these memories are systematic underestimates of past duration. People appear to underestimate future event duration because they underestimate past event duration.

Forecasting↗

PubMed2005

The broad applicability of memory bias and its coexistence with the planning fallacy: reply to Griffin and Buehler (2005).

People chronically underestimate how long tasks will take. In their original article, the present authors (M. M. Roy, N. J. S. Christenfeld, & C. R. M. McKenzie, suggested a simple, broadly applicable explanation: Biased predictions result from biased memories. In their comment article, D. Griffin and R. Buehler suggested that in many domains in which this memory-bias account appears to out-predict their own account, theirs actually makes no prediction at all. However, the present authors did not suggest that only 1 theory is right but that theirs is consistent with data that prior theories, including their own, cannot explain. Ignoring memories of past tasks is not a complete explanation for the phenomenon if the memories people could consult are themselves biased. Nonetheless, underestimating future task duration is almost certainly multiply determined, and thus our account and theirs can coexist.

Attitude↗

PubMed2004

Explaining purportedly irrational behavior by modeling skepticism in task parameters: an example examining confidence in forced-choice tasks.

Many purported demonstrations of irrational behavior rely on the assumption that participants believe key task parameters that are merely asserted by experimenters. For example, previous researchers have found that participants who first reported confidence in items presented in a yes-no format did not change confidence to the degree prescribed by the normative model when those same items were later presented in a forced-choice format. A crucial assumption, however, was that participants fully believed the assertion that the forced-choice items were mutually exclusive and exhaustive. In this article, the authors derive and test a new normative model in which it is not assumed that participants fully believe the assertion. Two visual identification experiments show that the new normative model provides a compelling account of participants' confidence reports.

Attitude↗

PubMed2004

Framing effects in inference tasks--and why they are normatively defensible.

Framing effects occur when logically equivalent redescriptions of objects or outcomes lead to different behaviors, and, traditionally, such effects have been seen as irrational. However, recent evidence has shown that a speaker's choice among logically equivalent attribute frames can implicitly convey (or "leak") normatively relevant information about the speaker's reference point, among other things. In a reinterpretion of data published elsewhere, in this article it is shown that some common effects in inference tasks (covariation assessment and hypothesis testing) can also be seen as framing effects, thereby expanding the domain of framing. It is also shown that these framing effects are normatively defensible because normatively relevant information about event rarity is leaked through the description of data and through the phrasing of hypotheses, thereby broadening the information leakage approach to explaining framing effects. Information leakage can also explain why framing effects in such inference tasks disappear under certain conditions.

Choice Behavior↗

PubMed2003

What a speaker's choice of frame reveals: reference points, frame selection, and framing effects.

Framing effects are well established: Listeners' preferences depend on how outcomes are described to them, or framed. Less well understood is what determines how speakers choose frames. Two experiments revealed that reference points systematically influenced speakers' choices between logically equivalent frames. For example, speakers tended to describe a 4-ounce cup filled to the 2-ounce line as half full if it was previously empty but described it as half empty if it was previously full. Similar results were found when speakers could describe the outcome of a medical treatment in terms of either mortality or survival (e.g., 25% die vs. 75% survive). Two additional experiments showed that listeners made accurate inferences about speakers' reference points on the basis of the selected frame (e.g., if a speaker described a cup as half empty, listeners inferred that the cup used to be full). Taken together, the data suggest that frames reliably convey implicit information in addition to their explicit content, which helps explain why framing effects are so robust.

Choice Behavior↗

PubMed2002

When wrong predictions provide more support than right ones.

Correct predictions of rare events are normatively more supportive of a theory or hypothesis than correct predictions of common ones. In other words, correct bold predictions provide more support than do correct timid predictions. Are lay hypothesis testers sensitive to the boldness of predictions? Results reported here show that participants were very sensitive to boldness, often finding incorrect bold predictions more supportive than correct timid ones. Participants were willing to tolerate inaccurate predictions only when predictions were bold. This finding was demonstrated in the context of competing forecasters and in the context of competing scientific theories. The results support recent views of human inference that postulate that lay hypothesis testers are sensitive to the rarity of data. Furthermore, a normative (Bayesian) account can explain the present results and provides an alternative interpretation of similar results that have been explained using a purely descriptive model.

Adult↗