Temporal Attention, the Sunk Cost Effect, and Delay Discounting

The sunk cost effect, known as the degree to which an initial investment of time, effort, or money increases the likelihood of continued investment, and delay discounting, defined as how rapidly the subjective value of a reward declines as a function of the delay to its receipt, incorporate the role of temporally distant stimuli, but have not been evaluated simultaneously. One process that may link the two phenomena is the temporal attention hypothesis, which holds that the degree to which one perceives distant events as close to the present, and one’s ability to shift their temporal focus from now to not now, jointly contributes to the mechanism of delay discounting. The first of the two experiments showed that participants with higher subjective time perception (i.e., perceived distant objective time points as subjectively closer to the present) committed more sunk cost across hypothetical temporal gaps between the initial and terminal links, and exhibited lower rates of delay discounting than those with lower subjective time perception. In Experiment 2, the same sunk cost procedure was used, except that four temporal gap conditions were used that matched the time points used in the delay discounting task. Further, participants experienced either negative, neutral, or positively valenced income narratives, which have previously been shown to alter rates of delay discounting. Additionally, probed time points in the future and past subjective time perception tasks more closely matched those used in the delay discounting and sunk cost tasks, and both future and past subjective time perception were derived used Mazur’s (1987) hyperbolic model. A series of Quade non-parametric ANCOVAs failed to reveal a significant effect of income narrative on delay discounting, any measure of sunk cost, future or past subjective time perception, and past, present, and future temporal focus. Extra sum of squares tests revealed, however, that hyperboloid models of mean sunk cost and median indifference data across the three groups were better fit to separate curves than one curve. Hyperbolic decline in subjective time perception (Ln (k)) for future and past subjective time perception were strongly correlated and were combined together to form the measure joint time perception, which correlated with delay discounting, but did not correlate with any measure of sunk cost. Future subjective time perception was divided by past subjective time perception to form the measure of time perception index, which was only correlated with sunk cost measures, but not delay discounting. Overall sunk cost (i.e., terminal investment percentage of $5 initial investments subtracted by$35 initial investments) was directly correlated with delay discounting such that greater amounts of sunk cost related to lower rates of delay discounting, providing added evidence that the sunk cost effect may relate to lower rates of discounting. Implications, limitations, and future directions related to these findings are discussed

TWO STEPS FORWARD ONE STEP BACK? DELAY DISCOUNTING OF MONEY AND RUNNING IN MARATHON RUNNERS

Delay discounting and physical exercise tend to be independently explored, despite the increasing role of both areas within substance abuse research. Delay discounting is primarily used to uncover addiction related phenomena, whereas physical exercise is studied as a treatment for substance abuse. Few studies, however, have evaluated delay discounting and physical exercise within the context of substance use. Further, samples with a narrow range of fitness are often used, a problem that is compounded by not measuring discounting for exercise related rewards. In the current study, 40 ultra, full, or half-marathon runners completed a Monetary Choice Questionnaire (MCQ) and a modified version of the MCQ using minutes of running as the reward (RCQ). Participants were asked how many minutes of running were worth $100 to them (Running valuation) and to report their weekly number of alcoholic drinks consumed. Minutes of running was discounted at significantly higher rates than money. Interestingly, higher relative rates of discounting on the RCQ and higher running valuation were significantly associated with fewer alcoholic drinks consumed per week. Individuals who exhibited this pattern were also more likely to display lower rates of discounting for money in contrast to those with lower rates of discounting on the RCQ and lower running valuation. Although promising, future research with clinical populations is needed in order to make more firm conclusions regarding discounting and physical exercise

Competing neurobehavioral decision systems and the neuroeconomics of craving in opioid addiction

Craving is typically thought of as a classically conditioned response characterized by an elevated mesolimbic dopamine response to drug-related stimuli. Although this definition has spurred considerable research, the clinical impact of the research conducted has been less robust. The current review takes a more contemporary approach by conceptualizing craving as the breakdown of executive function and relative strengthening of the limbic system, occurring in the presence of conditioned cues, leading to a maladaptive craving response (ie, an increased likelihood of drug consumption). Working from this framework, the present review focuses on four issues in drug craving research: pivotal findings and limitations of cue-reactivity and neurocognitive tasks; two main processes of craving that include self-control and reward-based explanations; integration of neuroeconomic approaches to craving; and the theoretical implications and future directions of drug craving research

Sunk costs, psychological symptomology, and help seeking

Individuals often allow prior investments of time, money or effort to influence their current behavior. A tendency to allow previous investments to impact further investment, referred to as the sunk-cost fallacy, may be related to adverse psychological health. Unfortunately, little is known about the relation between the sunk-cost fallacy and psychological symptoms or help seeking. The current study used a relatively novel approach (i.e., Amazon.com’s Mechanical Turk crowdsourcing [AMT] service) to examine various aspects of psychological health in internet users (n = 1053) that did and did not commit the sunk-cost fallacy. In this observational study, individuals logged on to AMT, selected the “decision making survey” amongst the array of currently available tasks, and completed the approximately 200-question survey (which included a two-trial sunk cost task, the brief symptom inventory 18, the Binge Eating Scale, portions of the SF-8 health survey, and other questions about treatment utilization). Individuals that committed the fallacy reported a greater number of symptoms related to Binge Eating Disorder and Depression, being bothered more by emotional problems, yet waited longer to seek assistance when feeling ill. The current findings are discussed in relation to promoting help-seeking behavior amongst individuals that commit this logical fallacy

Impaired Brain Dopamine and Serotonin Release and Uptake in Wistar Rats Following Treatment with Carbotplatin

Chemotherapy-induced cognitive impairment, known also as “chemobrain”, is a medical complication of cancer treatment that is characterized by a general decline in cognition affecting visual and verbal memory, attention, complex problem solving skills, and motor function. It is estimated that one-third of patients who undergo chemotherapy treatment will experience cognitive impairment. Alterations in the release and uptake of dopamine and serotonin, central nervous system neurotransmitters that play important roles in cognition, could potentially contribute to impaired intellectual performance in those impacted by chemobrain. To investigate how chemotherapy treatment affects these systems, fast-scan cyclic voltammetry (FSCV) at carbon-fiber microelectrodes was used to measure dopamine and serotonin release and uptake in coronal brain slices containing the striatum and dorsal raphe nucleus, respectively. Measurements were taken from rats treated weekly with selected doses of carboplatin and from control rats treated with saline. Modeling the stimulated dopamine release plots revealed an impairment of dopamine release per stimulus pulse (80% of saline control at 5 mg/kg and 58% at 20 mg/kg) after 4 weeks of carboplatin treatment. Moreover, Vmax, the maximum uptake rate of dopamine, was also decreased (55% of saline control at 5 mg/kg and 57% at 20 mg/kg). Nevertheless, overall dopamine content, measured in striatal brain lysates by high performance liquid chromatography, and reserve pool dopamine, measured by FSCV after pharmacological manipulation, did not significantly change, suggesting that chemotherapy treatment selectively impairs the dopamine release and uptake processes. Similarly, serotonin release upon electrical stimulation was impaired (45% of saline control at 20 mg/kg). Measurements of spatial learning discrimination were taken throughout the treatment period and carboplatin was found to alter cognition. These studies support the need for additional neurochemical and behavioral analyses to identify the underlying mechanisms of chemotherapy-induced cognitive disorders