Keith Jacks Gamble

Poor Decision Making Is a Consequence of Cognitive Decline among Older Persons without Alzheimer’s Disease or Mild Cognitive Impairment

Objective Decision making is an important determinant of health and well-being across the lifespan but is critical in aging, when many influential decisions are made just as cognitive function declines. Increasing evidence suggests that older adults, even those without dementia, often make poor decisions and are selectively vulnerable to scams. To date, however, the factors associated with poor decision making in old age are unknown. The objective of this study was to test the hypothesis that poor decision making is a consequence of cognitive decline among older persons without Alzheimer’s disease or mild cognitive impairment. Methods Participants were 420 non-demented persons from the Memory and Aging Project, a longitudinal, clinical-pathologic cohort study of aging in the Chicago metropolitan area. All underwent repeated cognitive evaluations and subsequently completed assessments of decision making and susceptibility to scams. Decision making was measured using 12 items from a previously established performance-based measure and a self-report measure of susceptibility to scams. Results Cognitive function data were collected over an average of 5.5 years prior to the decision making assessment. Regression analyses were used to examine whether the prior rate of cognitive decline predicted the level of decision making and susceptibility to scams; analyses controlled for age, sex, education, and starting level of cognition. Among 420 persons without dementia, more rapid cognitive decline predicted poorer decision making and increased susceptibility to scams (p’s<0.001). Further, the relations between cognitive decline, decision making and scams persisted in analyses restricted to persons without any cognitive impairment (i.e., no dementia or even mild cognitive impairment). Conclusions Poor decision making is a consequence of cognitive decline among older persons without Alzheimer’s disease or mild cognitive impairment, those widely considered “cognitively healthy.” These findings suggest that even very subtle age-related changes in cognition have detrimental effects on judgment.

Does Presenting Investment Results Asset by Asset Lower Risk Taking

We examine how the presentation of investment results affects risk taking using an experiment in which participants view results either asset by asset or aggregated into a portfolio result. Our experiment examines the investment choices of a nationwide sample of 249 participants in a simulation of investing for retirement. Segregating investment results by asset decreases subsequent risk taking. Those presented segregated results lower their equity proportion by 4.21% and their portfolio volatility by 0.88%. Both decreases are 8% of the mean levels of risk taking, 50.59% and 10.85% respectively. At the beginning of the simulation, we present historical results of the investment options either asset by asset or aggregated into portfolios. Among the small number of participants who spend a significant amount of time studying these historic results, segregating results lowers their equity proportion by 9.81%. Our results are a challenge to fully rational theories of investment choice, but are consistent with a combination of three aspects of prospect theory based models: loss aversion, narrow framing of individual-asset results, and diminishing sensitivity to aggregated gains and losses. Our experiment never varies the presentation of investment results across time, thus our results are distinct from the effect of myopic loss aversion.

Temporal Discounting Is Associated with an Increased Risk of Mortality among Community-Based Older Persons without Dementia

Background Temporal discounting is an important determinant of many health and financial outcomes, but we are not aware of studies that have examined the association of temporal discounting with mortality. Methods Participants were 406 older persons without dementia from the Rush Memory and Aging Project, a longitudinal cohort study of aging. Temporal discounting was measured using standard preference elicitation questions. Individual discount rates were estimated using a well-established hyperbolic function and used to predict the risk of mortality during up to 5 years of follow-up. Results The mean estimate of discounting was 0.45 (SD = 0.33, range: 0.08–0.90), with higher scores indicating a greater propensity to prefer smaller immediate rewards over larger but delayed ones. During up to 5 years of follow-up (mean = 3.6 years), 62 (15% of 406) persons died. In a proportional hazards model adjusted for age, sex, and education, temporal discounting was associated with an increased risk of mortality (HR = 1.103, 95% CI 1.024, 1.190, p = 0.010). Thus, a person with the highest discount rate (score = 0.90) was about twice more likely to die over the study period compared to a person with the lowest discount rate (score = 0.08). Further, the association of discounting with mortality persisted after adjustment for the level of global cognitive function, the burden of vascular risk factors and diseases, and an indicator of psychological well being (i.e., purpose in life). Conclusion Temporal discounting is associated with an increased risk of mortality in old age after accounting for global cognitive function and indicators of physical and mental health.

Aging, Financial Literacy, and Fraud

This study examines how cognitive changes associated with aging impact the financial decision making capability of older Americans. We find that a decrease in cognition is associated with a decrease in financial literacy. Decreases in episodic memory, perceptual speed, and visuospatial ability are associated with a decrease in numeracy, and decreases in episodic and semantic memory are associated with a decrease in financial knowledge. A decrease in cognition also predicts a drop in self-confidence in general, but importantly, it is not associated with a drop in confidence in managing ones own finances. Participants experiencing decreases in cognition do show an increased likelihood of getting help with financial decisions; however, many participants experiencing significant drops in cognition still do not get help. This study also examines the risk factors for an older American being victimized by financial fraud. We find that overconfidence in one’s financial knowledge is a significant predictor of the odds of falling victim.

Informed Short Selling around SEO Announcements

While much of the prior research on short selling around announcements of seasoned equity offerings (SEOs) has focused on manipulation, it is unclear whether there is also informed short selling around these announcements. We test for informed short selling around SEO announcements by examining the relation between i) pre-announcement short selling and the announcement-period return and ii) changes in short interest around the SEO announcement and the long-term operating and stock price performance following the equity issue. We find that firms with large increases in short interest prior to the SEO announcement exhibit lower (i.e., more negative) announcement-period returns, and that firms with large increases in short interest around the SEO announcement experience inferior long-term operating and stock price performance following the equity issue. We also find that the negative relation between large increases in short interest and long-term operating and stock price performance is more pronounced among shelf offers. This result highlights the informational role of short sellers in identifying opportunistic market timers of equity issues among shelf filers. Our overall results indicate the presence of informed short selling around SEO announcements.

How Prior Outcomes Affect Individual Investors' Subsequent Risk Taking

We present empirical evidence of how prior outcomes affect individual investors’ subsequent risk taking. Investors who experience big gains or big losses are likely to exit the stock market; however, investors remaining in the market increase their portfolio risk taking following losses. They replace stocks sold with new positions of a higher (lower) value following recent losses (gains), thereby leading to an increase (decrease) in overall stock portfolio risk taking. Our results are consistent with the predictions of consumption habit formation interacting with the disposition effect. Our results cannot be explained by information, simple rebalancing, the house money effect, or the break even effect.

The Information Content of Investors' Expectations for Risk and Return

This study reveals the information content of individual investors’ risk-adjusted return expectations. Although individual investors overestimate the performance of their stock purchases on average, the cross-sectional variation in their risk-adjusted return expectations is predictive of future risk-adjusted stock performance. Stock purchases that investors expect to outperform the most do outperform the stock purchases that investors expect to outperform the least by an annualized alpha of 16%. The best performing stocks are those that investors with excellent experience expect to outperform the most while the worst performing stocks are those that investors with limited experience expect to outperform the least. The most experienced investors appear to be successfully using information gathered from personal experience with the companys products or services, contact with someone who works for or with the company on a regular basis, and proximity to the companys operations.