We investigate the role that self-control problems — modeled as time-inconsistent, present-biased preferences —and a person’s awareness of those problems might play in leading people to develop and maintain harmful addictions. Present-biased preferences create a tendency to over-consume addictive products, and awareness of future self-control problems can mitigate or exacerbate this over-consumption, depending on the environment. Our central concern is the welfare consequences of this over-consumption. Our analysis suggests that for realistic environments self-control problems are a plausible source of severely harmful addictions only in conjunction with some unawareness of future self-control problems.

Previous papers on time-inconsistent procrastination assume projects are completed once begun. We develop a model in which a person chooses whether and when to complete each stage of a long-term project. In addition to procrastination in starting a project, a naive person might undertake costly effort to begin a project but then never complete it. When the costs of completing different stages are more unequal, procrastination is more likely, and it is when later stages are more costly that people start but don't finish projects. Moreover, if the structure of costs over the course of a project is endogenous, people are prone to choose cost structures that lead them to start but not finish projects. We also consider several extensions of the model that further illustrate how people may incur costs on projects they never complete.

Project 1: Schistosomiasis is a neglected tropical disease with a single drug available: Praziquantel. Using substrate profiling by mass spectrometry on S. mansoni proteasome, we obtained the substrate specificity profile for the β1, β2 and β5 subunits of the proteasome. Novel fluorogenic substrates were designed. The new β5 substrate (FNKL-AMC) proved to be much more potent than the commercial substrate (LLVY-AMC). These substrates demonstrated similar activity in three Schistosoma species, proving that they can detect proteasome activity in more than just S. mansoni. Project 2: Finding novel drug targets within the parasite is needed. Dr. James Collins and his team performed a comprehensive single-cell RNAseq on adult Schistosoma. They categorized 43,642 cells and assigned them into 68 distinctive populations. A homologue of hepatocyte nuclear factor 4 (hnf4) was discovered in a lineage of gut cells. The cathepsin activity in worms that received RNAi of hnf4 was measured. It was revealed that cathepsin B activity was decreased 8.2-fold relative to the control group. I showed that hnf4 is essential for the cathepsin-mediated hemoglobin digestion of S. mansoni. Project 3: Marine natural products possess diverse biological activities. IC50 values of Tutuilamide A-C and two additional analogues were calculated for pancreatic elastase, fungal proteinase K, trypsin, and chymotrypsin. Tutuilamide A and B demonstrated potent IC50 values against pancreatic elastase (1.18 nM and 2.05 nM, respectively) and proteinase K (103.7 nM and 87.6 nM, respectively). These compounds proved to be 2 to 4-fold more potent compared to previously studied elastase inhibitor lyngbyastatin 7.

Recent models of procrastination due to self-control problems assume that a procrastinator considers just one option and is unaware of her self-control problems. We develop a model where a person chooses from a menu of options and is partially aware of her self-control problems. This menu model replicates earlier results and generates new ones. A person might forego completing an attractive option because she plans to complete a more attractive but never-to-be-completed option. Hence, providing a non-procrastinator additional options can induce procrastination, and a person may procrastinate worse pursuing important goals than unimportant ones.

This paper explores some of the ways that economists can incorporate insights from recent research combining psychology and economics to help understand risky behavior by adolescents.

Previous papers on time-inconsistent procrastination assume projects are completed once begun. We develop a model in which a person chooses whether and when to complete each stage of a long-term project. In addition to procrastination in starting a project, a naive person might undertake costly effort to begin a project but then never complete it. When the costs of completing different stages are more unequal, procrastination is more likely, and it is when later stages are more costly that people start but don't finish projects. Moreover, if the structure of costs over the course of a project is endogenous, people are prone to choose cost structures that lead them to start but not finish projects. We also consider several extensions of the model that further illustrate how people may incur costs on projects they never complete.