Hundreds of experiments have examined people’s ability to distinguish truths from lies. Meta-analyses suggest that the findings from larger scale experiments converge and that findings discrepant from the meta-analytic average of 54% occur in only smaller experiments. Study size (number of data points, or total number of judgments) is a joint function of the sample size and the number of judgments per research participant. Furthermore, because senders vary more than judges, experiments involving few senders may not be replicable. A number of simulations are reported in which the sample size, the number of unique senders, and the number of judgments per research participant are varied. The findings demonstrate that stability is more a function of the number of judgments than the sample size and that experiments involving too few senders risk idiosyncratic findings that are less likely to be replicable. Implications for research design are discussed.

Research on elderly financial exploitation has mostly focused on financial abuse that occurs in families and other types of trusted relationships. As such, little is known about financial frauds and scams perpetrated by strangers. Financial fraud and scam prevention activities for older adults must be promoted, for which the correlation between the psychological, social, and cognitive characteristics of their vulnerability needs to be determined. The present study aimed to determine whether cognitive decline is a risk factor for scam vulnerability in older adults. Thus, we created a scam vulnerability scale for older adults with cognitive decline and analyzed the data to reveal the correlation between them, including inhibition and executive function. We conducted an interview survey with 50 older adults with cognitive decline (average age: 79.42 years, SD: 5.44) and 51 older adults without cognitive decline (average age: 76.12 years, SD: 5.82). The interview survey included the scam vulnerability scale, psychosocial questionnaires, and neuropsychological tests. The scale included six items with a four-point Likert scale based on a previous study. Hierarchical multiple regression analysis revealed that lower scores on the Japanese version of the Alzheimer's Disease Assessment Scale–Cognitive Subscale (ADAS-Jcog; indicating higher general cognitive function) correlated with higher scam vulnerability in the cognitive decline group (β = −0.46, p < 0.001). In addition, men were found to be more vulnerable in both groups (cognitive decline group: β = −0.29, p = 0.015, cognitive non-decline group; β = −0.32, p = 0.018). Inhibition and executive function were found not to correlate significantly with scam vulnerability. These results suggest that mild cognitive decline correlates with higher scam vulnerability, whereas moderate to severe cognitive decline correlates with lower vulnerability, possibly because it makes understanding the scam attempt itself difficult. Older adults with mild cognitive decline and their families, particularly those visiting elderly care or outpatient facilities, should be notified of the scam vulnerability of older clients using the ADAS-Jcog score as an index to help them avoid victimization.

Truth-Default Theory (TDT) predicts that across countries and cultures, a few people tell most of the lies, while a majority of people lie less frequently than average. This prediction, referred to as “a few prolific liars,” is tested in Japan. The study further investigated the extent to which the Dark Triad personality traits predict the frequency of lying. University students (N = 305) reported how many times they lied in the past 24 hours and answered personality questions. Results indicate that the few prolific liars pattern is evident in Japan thereby advancing TDT. Results also show that Japanese frequent liars tend to have Dark Triad personality traits, but the nature of the findings may be unique to Japan. Results of the generalized linear model suggest that the Dark Triad components of Machiavellianism and psychopathy exacerbate lying behavior by reducing the guilt associated with lying. However, narcissism encourages guilt and therefore inhibits lying behavior with both direct and indirect effects. These narcissism findings appear to contradict prior studies but stem from use of a more appropriate statistical analysis or the Japanese context.

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