Suzanne H Mitchell

• Ph.D.
• Professor (Full) at Oregon Health & Science University

Delay discounting refers to the behavioral tendency to devalue rewards as a function of their delay in receipt. Heightened delay discounting has been associated with substance use disorders and multiple co‐occurring psychopathologies. Human and animal genetic studies have established that delay discounting is heritable, but only a few associated ge...

Organisms must regulate their behavior flexibly in the face of environmental challenges. Failure can lead to a host of maladaptive behavioral traits associated with a range of neuropsychiatric disorders, including attention deficit hyperactivity disorder, autism, and substance use disorders. This maladaptive dysregulation of behavior is influenced...

Delay discounting is the process by which outcomes (rewards or punishment) are devalued as a function of the delay to their occurrence. The adjusting amount procedure enables researchers to measure how much an individual discounts the value of a reward as a function of delay. Higher levels of delay discounting have been associated with psychopathol...

Delay discounting refers to the behavioral tendency to devalue rewards as a function of their delay in receipt. Heightened delay discounting has been associated with substance use disorders, as well as multiple co-occurring psychopathologies. Genetic studies in humans and animal models have established that delay discounting is a heritable trait, b...

Organisms must regulate their behavior flexibly in the face of environmental challenges. Failure can lead to a host of maladaptive behavioral traits associated with a range of neuropsychiatric disorders, including attention deficit hyperactivity disorder, autism, and substance use disorders. This maladaptive dysregulation of behavior is influenced...

Choice behavior requires animals to evaluate both short- and long-term advantages and disadvantages of all potential alternatives. Impulsive choice is traditionally measured in laboratory tasks by utilizing delay discounting (DD), a paradigm that offers a choice between a smaller immediate reward, or a larger more delayed reward. This study tested...

Background Studies in animals and humans suggest that greater levels of sensation seeking and alcohol use are related to individual differences in drug‐induced dopamine release. However, it remains unclear whether drug‐induced alterations in the functional synchrony between mesostriatal regions are related to sensation seeking and alcohol use. Met...

The stability of delay discounting across time has been well-established. However, limited research has examined the stabil- ity of probability discounting, and no studies of the stability of effort discounting are available. The present study assessed the steady-state characteristics of delay, probability, and effort discounting tasks across time...

Choice behavior requires animals to evaluate both short- and long-term advantages and disadvantages of all potential alternatives. Impulsive choice is traditionally measured in laboratory tasks by utilizing delay discounting (DD), a paradigm that offers a choice between a smaller immediate reward, or a larger more delayed reward. This study tested...

Introduction to the Rachlin Festschrift

In a recent issue of SLEEP, Lim et al. [1] report how different forms of sleep loss moderate risky decision-making, and how this effect is dependent on gender. This was a comprehensive study that deployed two assessments of risky decision-making (minimizing losses or maximizing gains), explored two types of sleep loss (a night of sleep deprivation...

ADHD is defined by behavioral symptoms that are not well characterized in relation to ADHD's neurobiological mechanisms. This approach has limited our ability to define ADHD nosology and predict outcomes because it does not systematically examine facets of the disorder such as the inability to maintain cognitively effortful activities, as promoted...

Background Transition to clerkship courses bridge the curricular gap between preclinical and clinical medical education. However, despite the use of simulation-based teaching techniques in other aspects of medical training, these techniques have not been adequately described in transition courses. We describe the development, structure and evaluati...

Rationale Alcohol-use disorder (AUD) is associated with the propensity to choose smaller sooner options on the delay discounting task. It is unclear, however, how inherent risk underlies delay discounting behavior. As impulsive choice is a hallmark feature in AUD, it is important to understand the neural response to reward and delay while accountin...

After publication of this paper, the authors determined an error in the funding information section CX17008-CDA2 should be CX001790 (MK).

Impulsivity has been linked to academic performance in the context of Attention Deficit Hyperactivity Disorder, though its influence on a wider spectrum of students remains largely unexplored, particularly in the context of STEM learning (i.e. science, technology, engineering, and math). STEM learning was hypothesized to be more challenging for imp...

Research supports the idea that “delay discounting,” also known as temporal discounting, intertemporal choice, or impulsive choice, is a transdisease process with a strong connection to substance use disorders (SUDs) and other psychopathologies, like attention deficit hyperactivity disorder and depression. This article briefly reviews the evidence...

Debates about the utility of p values and correct ways to analyze data have inspired new guidelines on statistical inference by the American Psychological Association (APA) and changes in the way results are reported in other scientific journals, but their impact on the Journal of the Experimental Analysis of Behavior (JEAB) has not previously been...

Objective: Although some research has identified correlates of high-dose opioid prescriptions, relatively little is known about factors that lead to higher doses. Delay discounting (DD), defined as the subjective value of a reward declining as a function of the delay to that reward, is an objective measure of impulsivity. DD is commonly studied in...

Hepatitis C virus-infected (HCV+) adults evidence increased rates of psychiatric and cognitive difficulties. This is the first study to use functional magnetic resonance imaging (fMRI) to examine brain activation in untreated HCV+ adults. To determine whether, relative to non-infected controls (CTLs), HCV+ adults exhibit differences in brain activa...

Impulsivity has been linked to academic performance in the context of Attention Deficit Hyperactivity Disorder, though its influence on a wider spectrum of students remains largely unexplored, particularly in the context of STEM learning (i.e. science, technology, engineering, and math). STEM learning was hypothesized to be more challenging for imp...

Method: The current study uses an accelerated longitudinal design and latent trajectory growth mixture models in a sample of children ages 7-13 years carefully characterized as with (n = 437) and without (n = 297) ADHD to (a) identify heterogeneous developmental trajectories for response inhibition, visual spatial working memory maintenance, and d...

The factors and mechanisms associated with choices between small rewards available immediately and larger rewards available following a delay have been the focus of research across several disciplines, due to the ubiquitous nature of these types of choice and the systematic effects of psychopathology on preferences. This chapter discusses practical...

Midbrain neurons of the centrally projecting Edinger–Westphal nucleus (EWcp) are activated by alcohol, and enriched with stress-responsive neuropeptide modulators (including the paralog of corticotropin-releasing factor, urocortin-1). Evidence suggests that EWcp neurons promote behavioral processes for alcohol-seeking and consumption, but a definit...

Attention deficit hyperactivity disorder (ADHD) and autism spectrum disorder (ASD) have been linked to prenatal risk factors including maternal obesity, stress, and viral infections during pregnancy. These risk factors share a common mechanism, elevated inflammatory cytokines and in particular, elevated interleukin-6 (IL-6). Resting state functiona...

Attention deficit hyperactivity disorder (ADHD) and autism spectrum disorder (ASD) have been linked to prenatal risk factors including maternal obesity, stress, and viral infections during pregnancy. These risk factors share a common mechanism, elevated inflammatory cytokines and in particular, elevated interleukin-6 (IL-6). Resting state functiona...

Introduction: Tobacco chippers are light smokers with stable patterns of smoking that exhibit lower nicotine dependence severity than heavy smokers. Chippers may provide valuable information about the factors influencing drug dependence. Impulsivity and stress are two factors known to influence smoking. By comparing non-dependent smokers (tobacco...

Changes in executive function are at the root of most cognitive problems associated with Parkinson's disease. Because dopaminergic treatment does not necessarily alleviate deficits in executive function, it has been hypothesized that dysfunction of neurotransmitters/systems other than dopamine (DA) may be associated with this decrease in cognitive...

Impulsivity critically relates to many psychiatric disorders. Given the multifaceted construct that impulsivity represents, defining core aspects of impulsivity is vital for the assessment and understanding of clinical conditions. Choice impulsivity (CI), involving the preferential selection of smaller sooner rewards over larger later rewards, repr...

Significance Noninvasive brain imaging holds great promise for expanding our capabilities of treating human neurologic and psychiatric disorders. However, key limitations exist in human-only studies, and the ability to use animal models would greatly advance our understanding of human brain function. Mice offer sophisticated genetic and molecular m...

Impulsive behavior is strongly implicated in drug abuse, as both a cause and a consequence of drug use. To understand how impulsive behaviors lead to and result from drug use, translational evidence from both human and non-human animal studies is needed. Here, we review recent (2009 or later) studies that have investigated two major components of i...

Background / Purpose: We designed a task that presented choices between an immediate, certain, fixed reward and an alternative reward that varied in magnitude, delay to receipt and certainty. We identified brain regions that responded parametrically to the characteristics of the alternate reward. We enrolled 30 control subjects and 34 methampheta...

Delay discounting (also intertemporal choice or impulsive choice) is the process by which delayed outcomes, such as delayed food delivery, are valued less than the same outcomes delivered immediately or with a shorter delay. This process is of interest because many psychopathologies, including substance dependence, pathological gambling, attention...

Background: Mice selectively bred for high or low withdrawal to acute alcohol differ on a number of traits, including consumption of alcohol, conditioned place preference for alcohol, and sensitivity to alcohol-induced locomotor activity. One trait that has not been examined in these mice is behavioral inhibition. Methods: High and low alcohol w...

Attention-deficit/hyperactivity disorder (ADHD) is a prevalent psychiatric disorder that has poor long-term outcomes and remains a major public health concern. Recent theories have proposed that ADHD arises from alterations in multiple neural pathways. Alterations in reward circuits are hypothesized as one core dysfunction, leading to altered proce...

Purpose To evaluate the effectiveness of a yoga intervention for smoking cessation. Methods A systematic search, review and synthesis of existing literature on yoga interventions for smoking cessation was conducted. Online literature searches through MEDLINE, PsycINFO, EBM, PubMed, clinicaltrials.gov and NIH RePORTER were carried out using an array...

The purpose of this study was to determine whether animals predisposed to prefer alcohol possess an altered acute response to alcohol on a delay discounting task relative to animals predisposed to avoid alcohol. We used rats selected to prefer or avoid alcohol to assess whether genotype moderates changes in delay discounting induced by acute ethano...

Ethanol (EtOH) administration decreases behavioral inhibition in human subjects, assessed using cued Go/No-Go tasks, in which an unreliable cue suggests whether participants will be required to respond or not when a signal occurs. Few studies have examined EtOH's effects on behavioral inhibition in animals, and those that have done so have used Go/...

Research indicates that genetics influence methamphetamine self-administration as well as sensitization to the psychomotor-stimulating effects of methamphetamine (MA). Other studies have suggested that heightened levels of impulsivity, including low levels of behavioral inhibition, are associated with the use of drugs, including MA. The current stu...

When offered a choice between a small monetary reward available immediately (SmallNow) versus a larger reward available after a delay (LargeLater), smokers select the SmallNow alternative more than nonsmokers. That is, smokers discount the value of the LargeLater reward more than nonsmokers. To investigate whether this group difference was due to s...

Excessive alcohol consumption in college students is associated with impulsivity and with overestimating levels of others' drinking; however, females' and males' drinking may be differently impacted by their overestimations. We examined whether moderate drinkers discount alcohol rewards differently from money rewards and whether their estimate of o...

Older adults' decision quality is considered to be worse than that of younger adults. This age-related difference is often attributed to reductions in risk tolerance. Little is known about the circumstances that affect older adults' decisions and whether risk attitudes directly influence economic decisions. We measure the influence of risk attitude...

In this article, we examine the relation between delay discounting and future time perspective by reviewing how these concepts have been measured and quantified in order to assess their conceptual similari-ties. The extent to which the different measures are empirically related is reviewed by describing studies that have assessed both constructs an...

Persons with severe and persistent mental illnesses, e.g. schizophrenia spectrum disorders and bipolar disorder, smoke at a much higher rate than the general population. Treatment options for schizophrenia spectrum disorders and bipolar disorder often include the first-generation (typical) and second-generation (atypical) antipsychotics, which have...

Objective: Determine whether adults with hepatitis C (HCV), regardless of substance use disorder, are more likely to discount delayed rewards than adults without hepatitis C, and explore the relationship between delay discounting and neuropsychological functioning. Methods: Procedures included clinical interviews, neuropsychological testing, and...

Delay discounting is steeper for individuals who drink heavily or are alcohol dependent, but the reasons for this are unclear. Given the substantial genetic component for alcohol dependence it is not unreasonable to ask whether discounting and alcohol dependence have a genetic relationship. For there to be a genetic relationship, delay discounting...

A key underlying process that may contribute to attention-deficit/hyperactivity disorder (ADHD) involves alterations in reward evaluation, including assessing the relative value of immediate over delayed rewards. This study examines whether children with ADHD discount the value of delayed rewards to a greater degree than typically developing childr...

Youth with family history of alcohol abuse have a greater risk of developing an alcohol use disorder (AUD). Brain and behavior differences may underlie this increased vulnerability. The current study examined delay discounting behavior and white matter microstructure in youth at high risk for alcohol abuse, as determined by a family history of alco...

High levels of impulsivity have been associated with a number of substance abuse disorders including alcohol abuse. Research has not yet revealed whether these high levels predate the development of alcohol abuse. The current study examined impulsivity in 15 inbred strains of mice (A/HeJ, AKR/J, BALB/cJ, C3H/HeJ, C57BL/6J, C57L/J, C58/J, CBA/J, DBA...

Alcohol use disorders (AUDs) are a devastating public health problem. The construct of impulsivity is biologically based and heritable, and its various dimensions are relevant for understanding alcohol use. The goal of the current manuscript is to review recent behavioral and biological research examining various dimensions of impulsivity and their...

Methamphetamine (MA) is associated with behavioral and cognitive deficits that may be related to macrostructural abnormalities. Quantitative anatomical comparisons between controls and methamphetamine-dependent individuals have produced conflicting results. We examined local and global differences in brain structure in 61 abstinent methamphetamine-...

There are well-established links between impulsivity and alcohol use in humans and other model organisms; however, the etiological nature of these associations remains unclear. This is likely due, in part, to the heterogeneous nature of the construct of impulsivity. Many different measures of impulsivity have been employed in human studies, using b...

This study examined the contribution of response bias to measures of delay discounting in Long-Evans rats (n=8) using the adjusting amount procedure. Under this procedure, we assessed preference for 150microl of 10% sucrose solution delivered following a delay over a variable-amount alternative delivered immediately. Bias was calculated based on re...

• The sections in this chapter represent the current understanding of delay discounting as applied to substance abuse. We begin with studies that have compared delay discounting of outcomes in the future (which we refer to here as delay discounting) by substance-abusing populations and nonusing controls. Noteworthy is that much of the literature re...

The subjective value of a reward (gain) is related to factors such as its size, the delay to its receipt and the probability of its receipt. We examined whether the subjective value of losses was similarly affected by these factors in 128 adults. Participants chose between immediate/certain gains or losses and larger delayed/probabilistic gains or...

A heightened aversion to delayed rewards is associated with substance abuse and numerous other neuropsychiatric disorders. Many of these disorders are heritable, raising the possibility that delay aversion may also have a significant genetic or heritable component. To examine this possibility, we compared delay discounting in six inbred strains of...

Alcoholics and heavy drinkers score higher on measures of impulsivity than nonalcoholics and light drinkers. This may be because of factors that predate drug exposure (e.g. genetics). This study examined the role of genetics by comparing impulsivity measures in ethanol-naive rats selectively bred based on their high [high alcohol drinking (HAD)] or...

Alleles of the human dopamine D(4) receptor (D(4)R) gene (DRD4.7) have repeatedly been found to correlate with novelty seeking, substance abuse, pathological gambling, and attention-deficit hyperactivity disorder (ADHD). If these various psychopathologies are a result of attenuated D(4)R-mediated signaling, mice lacking D(4)Rs (D(4)KO) should be mo...

Methamphetamine (MA)-dependent individuals prefer smaller immediate over larger delayed rewards in delay discounting (DD) tasks. Human and animal data implicate ventral (amygdala, ventral striatum, ventrolateral prefrontal cortex insula) and dorsal (dorsolateral prefrontal cortex, dorsal anterior cingulate cortex and posterior parietal cortex) syst...

Previous studies show that the basolateral amygdala (BLA) is required for behavior to adjust when the value of a reinforcer decreases after satiation or pairing with gastric distress. This study evaluated the effect of pre- or post-training excitotoxic lesions of the BLA on changes in preference with another type of contingency change, reinforcer m...

Self-report surveys and behavioral tasks indicate greater risk-taking behavior in adolescents as compared with adults. However, the underlying causes of these behavioral differences remain unclear. The present study examined the possibility that adolescents may be more susceptible to immediate positive and negative outcomes than adults. We compared...

Alcoholics and heavy drinkers score higher on measures of impulsivity than nonalcoholics and light drinkers. This may be due to factors that predate drug exposure (e.g. genetics) or to neuroadaptations associated with exposure to alcohol. The aim of this study was to examine the role of genetics by comparing impulsivity in short-term selected lines...

Methamphetamine (MA) dependence accounts for substantial neuropsychiatric morbidity. Furthermore, there is evidence in the literature of psychiatric and cognitive impairment in chronic users. This report compares the general psychiatric and cognitive functioning, including impulsive decision-making, of individuals dependent on MA and normal control...

Many studies have shown that human drug abusers are more impulsive than nonusers, but the mechanisms underlying this difference are unknown. C57BL/6J (B6) and DBA/2J (D2) mouse strains differ in sensitivity to the associative effects and in self-administration of several drugs of abuse. To determine whether these strains exhibit differences in impu...

Dopamine is critical for directing goal-oriented behavior. We investigated dopamine D2 receptor involvement in reversal learning and reinforcement efficacy in mice lacking functional dopamine D2 receptors and their heterozygous and wild-type littermates. Mice discriminated between two odors to receive a food reinforcer. One odor signaled a reinforc...

Alcoholic individuals discount the value of future rewards more steeply than social drinkers, which is viewed as symptomatic of higher levels of impulsivity. However, the mechanisms underlying this difference are unknown. This study examined 2 hypotheses about the relationship between discounting and ethanol's effects in mice: (1) steep discounters...

Two types of behavioral measure are primarily used to examine impulsivity in humans and animals: Go/No-go tasks to assess inhibition and relative preference tasks to assess delay aversion. Several examples of each type of task are described so that common cognitive processes and variables affecting performance can be identified. Data suggest that s...

Experimental evidence suggests that when opioid-dependent drug users are deprived of heroin, they become more likely to behave impulsively on a computer task. The current study examined whether nicotine deprivation has similar effects in cigarette smokers, causing an increase in impulsive decision-making. Simultaneously, the impact of deprivation o...

This paper reviews three variables that can be viewed as imposing a cost on the acquisition of a commodity. It also examines the discounting that occurs when costs other than delay to receipt are associated with a commodity, and the possible inter-relationships between different types of cost discounting. The effort required to obtain a commodity h...

It has been suggested that when the delivery of several rewards is separated in time, e.g. one reward immediately and a second reward a few moments later, the value of an alternative that includes these "bundled" rewards will be the sum of the hyperbolic discount functions of the individual rewards. The current study examined this hypothesis using...