Person:

Laibson, David

We identify employees at seven companies whose 401(k) investment choices are dominated because they are contributing less than the employer matching contribution threshold despite being vested in their match and being able to make penalty-free 401(k) withdrawals for any reason because they are older than 59½. At the average firm, 36% of match-eligible employees over age 59½ forgo arbitrage profits that average 1.6% of their annual pay, or $507. A survey educating employees about the free lunch they are forgoing raised contribution rates by a statistically insignificant 0.67% of income among those completing the survey.

We study whether prompts to form and recall a plan can increase individuals’ responsiveness to reminders to make and attend beneficial appointments. At four companies, all employees due for a colonoscopy were randomly assigned to receive either a control mailing or a treatment mailing. The mailings were identical except that the control mailing included a blank sticky note while the treatment mailing included a sticky note that prompted the recipient to write down the appointment date for a colonoscopy and the name of the doctor who would conduct the procedure. During the seven-month follow-up period, 7.2% of treatment employees received a colonoscopy compared to 6.2% of control employees, a statistically significant difference that is roughly equal to the variation in compliance associated with a 10 percent increase in the fraction of the procedure’s cost covered by insurance. The treatment effect was largest for demographic groups judged to be at the highest risk of failing to receive a colonoscopy due to forgetfulness.

We evaluate the results of a field experiment designed to measure the effect of prompts to form implementation intentions on realized behavioral outcomes. The outcome of interest is influenza vaccination receipt at free on-site clinics offered by a large firm to its employees. All employees eligible for study participation received reminder mailings that listed the times and locations of the relevant vaccination clinics. Mailings to employees randomly assigned to the treatment conditions additionally included a prompt to write down either (i) the date the employee planned to be vaccinated or (ii) the date and time the employee planned to be vaccinated. Vaccination rates increased when these implementation intentions prompts were included in the mailing. The vaccination rate among control condition employees was 33.1%. Employees who received the prompt to write down just a date had a vaccination rate 1.5 percentage points higher than the control group, a difference that is not statistically significant. Employees who received the more specific prompt to write down both a date and a time had a 4.2 percentage point higher vaccination rate, a difference that is both statistically significant and of meaningful magnitude.

We document the loan provisions in 401(k) savings plans and how participants use 401(k) loans. Although only about 22% of savings plan participants who are allowed to borrow from their 401(k) have such a loan at any given point in time, almost half had used a 401(k) loan over a longer, seven-year horizon. The probability of having a loan follows a hump-shaped pattern with respect to age, job tenure, account balance, and salary, but conditional on having a loan, loan size as a fraction of 401(k) balances declines with respect to these variables. Participants are less likely to use loans in plans that charge a higher interest rate, and loans are smaller when plans allow fewer simultaneously outstanding loans, impose a shorter maximum possible loan duration, or charge a lower interest rate.

We derive the first closed-form optimal refinancing rule: Refinance when the current mortgage interest rate falls below the original rate by at least (\frac{1}{ψ})[φ + W (− exp (−φ))]. In this formula W(.) is the Lambert W-function, ψ = (\frac{2 (ρ + λ)}{σ}), φ = 1 + ψ (ρ + λ)(\frac{κ/M}{(1 − τ )}), ρ is the real discount rate, λ is the expected real rate of exogenous mortgage repayment, σ is the standard deviation of the mortgage rate, κ/M is the ratio of the tax-adjusted refinancing cost and the remaining mortgage value, and τ is the marginal tax rate. This expression is derived by solving a tractable class of refinancing problems. Our quantitative results closely match those reported by researchers using numerical methods.

Extending Barro (1999) and Luttmer & Mariotti (2003), we introduce a new model of time preferences: the instantaneous-gratification model. This model applies tractably to a much wider range of settings than existing models. It applies to both complete- and incomplete-market settings and it works with generic utility functions. It works in settings with linear policy rules and in settings in which equilibrium cannot be supported by linear rules. The instantaneous-gratification model also generates a unique equilibrium, even in infinite-horizon applications, thereby resolving the multiplicity problem hitherto associated with dynamically inconsistent models. Finally, it simultaneously features a single welfare criterion and a behavioral tendency towards overconsumption

People have present-biased preferences: they choose more impatiently when choosing between an immediate reward and a delayed reward, than when choosing between a delayed reward and a more delayed reward. Following McClure et al. [McClure, S.M., Laibson, D.I., Loewenstein, G., Cohen, J.D. (2004). Separate neural systems value immediate and delayed monetary rewards. Science, 306, 503.], we find that areas in the dopaminergic reward system show greater activation when a binary choice set includes both an immediate reward and a delayed reward in contrast to activation measured when the binary choice set contains only delayed rewards. The presence of an immediate reward in the choice set elevates activation of the ventral striatum, pregenual anterior cingulate cortex and anterior medial prefrontal cortex. These dopaminergic reward areas are also responsive to the identity of the recipient of the reward. Even an immediate reward does not activate these dopaminergic regions when the decision is being made for another person. Our results support the hypotheses that participants show less affective engagement (i) when they are making choices for themselves that only involve options in the future or (ii) when they are making choices for someone else. As hypothesized, we also find that behavioral choices reflect more patience when choosing for someone else.

The daunting complexity of important financial decisions can lead to procrastination. We evaluate a low-cost intervention that substantially simplifies the retirement savings plan participation decision. Individuals received an opportunity to enroll in a retirement savings plan at a pre-selected contribution rate and asset allocation, allowing them to collapse a multidimensional problem into a binary choice between the status quo and the pre-selected alternative. The intervention increases plan enrollment rates by 10–20 percentage points. We find that a similar intervention can be used to increase contribution rates among employees who are already participating in a savings plan.

Lucas (1987, 2003) estimates that the cost of economic fluctuations is low; a social planner would pay no more than 0.1% of (permanent) consumption to eliminate all future business cycle fluctuations. The current paper extends Lucas’ calculations by studying the costs of fluctuations arising from asset bubbles. We estimate two classes of costs: consumption volatility due to asset bubbles in a representative agent economy and consumption volatility that arises because households have heterogeneous exposure to the bubble assets. We show that the magnitude of welfare costs is primarily driven by the existence of heterogeneity. Our benchmark calibration implies that the asset bubbles of the last decade generated a social welfare cost equal to a permanent 3% reduction in the level of national consumption. If assets are held proportionately across the population, these welfare costs fall by an order of magnitude. Our calculations are sensitive to the details of the calibration, including the degree of balance sheet and trading heterogeneity, the coefficient of relative risk aversion, and the magnitude of the asset bubble. Our preferred specifications generate welfare costs ranging from 1% to 10% of (permanent) national consumption.

General intelligence (g) and virtually all other behavioral traits are heritable. Associations between g and specific single-nucleotide polymorphisms (SNPs) in several candidate genes involved in brain function have been reported. We sought to replicate published associations between g and 12 specific genetic variants (in the genes DTNBP1, CTSD, DRD2, ANKK1, CHRM2, SSADH, COMT, BDNF, CHRNA4, DISC1, APOE, and SNAP25) using data sets from three independent, well-characterized longitudinal studies with samples of 5,571, 1,759, and 2,441 individuals. Of 32 independent tests across all three data sets, only 1 was nominally significant. By contrast, power analyses showed that we should have expected 10 to 15 significant associations, given reasonable assumptions for genotype effect sizes. For positive controls, we confirmed accepted genetic associations for Alzheimer’s disease and body mass index, and we used SNP-based calculations of genetic relatedness to replicate previous estimates that about half of the variance in g is accounted for by common genetic variation among individuals. We conclude that the molecular genetics of psychology and social science requires approaches that go beyond the examination of candidate genes.