Area under the curve as a measure of discounting

We describe a novel approach to the measurement of discounting based on calculating the area under the empirical discounting function. This approach avoids some of the problems associated with measures based on estimates of the parameters of theoretical discounting functions. The area measure may be easily calculated for both individual and group data collected using any of a variety of current delay and probability discounting procedures. The present approach is not intended as a substitute for theoretical discounting models. It is useful, however, to have a simple, univariate measure of discounting that is not tied to any specific theoretical framework.     

American base‐rate neglect: It is not the math,but the context

We investigate cross‐cultural disparities in focalism bias through two studies of probability estimation. Using 60 American and 60 Chinese participants, Experiment 1 yields the standard finding that Americans manifest greater focalism bias by tending to neglect background probability base‐rates and to rely more heavily on obtained samples in estimating true probabilities, whereas Chinese participants show little tendency to ignore base‐rates. In Experiment 2, the phrasing of the probability‐estimation task is changed to bring base‐rates into the focus of the problem statement, again using a sample of 60 Americans and 60 Chinese. This allows us to test whether cross‐cultural differences result from a tendency to focus on the sample, and ignore ‘context’ (i.e., the background base‐rates), rather than simply a discrepancy in mathematical facility between the two groups. The results show far less base‐rate neglect for Americans, but essentially no change for Chinese (who always use base‐rate information, regardless of how presented). This outcome argues against the explanation that Americans are poorer Bayesians simply because they are weaker mathematicians. Implications are discussed.     

Preliminary investigation of two functional assessment methods for people with dementia: Effectiveness and acceptability

Many functional assessment procedures have been developed and validated for use with people with intellectual and developmental disabilities. However, there is a paucity of research exploring the utility and social acceptability of functional assessment methods for people with dementia. We conducted direct observations in the natural environment to produce data for conditional probability analyses and an experimental functional analysis of the behavior of two women with dementia. We found that the conditional probability analysis yielded similar conclusions about function as the data from the experimental functional analysis for both participants. Importantly, staff rated the direct observations as more socially acceptable. We also report barriers to conducting both methods in older adult settings that warrant further exploration, including the use of the assessments with people with dementia and intact vocal verbal repertoires.     

Harming is more intentional than helping because it is more probable: the underlying influence of probability on the Knobe effect

Knobe [2003. Intentional action and side effects in ordinary language. Analysis, 63, 190–194] demonstrated that people’s intentionality judgments in side effects depend on the outcome of the side-effect, indicating that people’s judgments of intentionality of action depend on not only the intention of the actor but also on the result of the action. However, on the basis of findings in judgment and decision making, the current study proposes another hypothesis to Knobe’s (2003) results: the participants’ intentionality judgments are related to not only the outcomes themselves but also the probabilities of outcomes predicted from the action. To test this hypothesis, the present study employed an identical experimental procedure to Knobe (2003), except that it required not only intentionality but also probability judgments for outcomes that resulted from the actions of a company president. The results replicated the findings of Knobe (2003) and showed a relationship between probability and intentionality judgment.     

An a priori solution to the replication crisis

Possibly, the replication crisis constitutes the most important problem in psychology. It calls into question whether psychology is a science. Existing conceptualizations of replicability depend on effect sizes; the larger the population effect size, the greater the probability of replication. This is problematic and contributes to the replication crisis. A different conceptualization, not dependent on population effect sizes, is desirable. The proposed solution features the closeness of sample means to their corresponding population means, in both the original and replication experiments. If the researcher has specified the sampling precision desired, it is possible to calculate the probability of replication, prior to data collection, and without dependence on the population effect size or expected population effect size. In addition, it is not necessary to know population means or standard deviations, nor sample means or standard deviations, to employ the proposed a priori way of thinking about replicability.     

The conjunction fallacy in profiles of victims of homicide

Using basic probability theory, estimates of the characteristics of the average homicide victim are calculated using the notion of disjoint probability. The assumption of disjoint events (e.g., the victim's race bears no effect on the offender's weapon choice) is then tested empirically using the Uniform Crime Report‐Supplementary Homicide Report. Exploratory results suggest that many demographic and situational characteristics taken together are only slightly more related than chance. Put simply, the average profile of homicide victims portrayed by the media becomes less likely as demographic variables are added. A survey was conducted to test whether individuals conjoined these characteristics, thinking they were more likely to occur together. Consistent with the conjunction fallacy, many participants overestimated the likelihood that certain demographic or situational characteristics will occur together, and some overestimated it to a mathematically impossible degree. These two experiments showcase the difficulty in displaying statistical profiling and how it affects the public's perception of offenders.     

Undermined

A popular strategy for understanding the probabilities that arise in physics is to interpret them via reductionist accounts of chance—indeed, it is sometimes claimed that such accounts are uniquely well-suited to make sense of the probabilities in classical statistical mechanics. Here it is argued that reductionist accounts of chance carry a steep but unappreciated cost: when applied to physical theories of the relevant type, they inevitably distort the relations of probability that they take as input.     

There is a 60% probability,but I am 70% certain: communicative consequences of external and internal expressions of uncertainty

Current theories of probability recognise a distinction between external (un)certainty (frequentistic probabilities) and internal (un)certainty (degrees of belief). The present studies investigated this distinction in lay people's judgements of probability statements formulated to suggest either an internal (“I am X% certain”) or an external (“It is X% certain” or “There is an X% probability”) interpretation. These subtle differences in wording influenced participants' perceptions and endorsements of such statements, and their impressions of the speaker. External expressions were seen to signal more reliable task duration estimates, and a lower degree of external than internal certainty was deemed necessary to advise a course of action. In conversations about football, internal expressions were perceived as signalling more personal interest, and were expected to be on the average 10% higher than corresponding external probabilities. Finally, people who reported their outcome expectations for two major sports events let their degree of interest in these events influence their internal but not their external certainty. These results have implications for the communication of uncertainty and probability.