Mindfulness and decision making: sunk costs or escalation of commitment?

Mindfulness is related to a number of positive health outcomes, such as decreased stress, anxiety and improved physical functioning. Recent studies have found that mindfulness is related to a range of cognitive outcomes, including better decision making. In one example, higher trait mindfulness and brief mindfulness inductions are associated with resistance to the influence of sunk costs, where mindful individuals were more willing to discontinue a costly, but disadvantageous, course of action. However, some previous studies examining mindfulness and sunk costs have methodological limitations which make it difficult to determine if mindfulness is specifically related to sensitivity to the sunk cost bias, or rather than to a general willingness to continue an unprofitable course of action (independent of the level of prior investment). The present study extends previous work by replicating the finding that trait mindfulness is positively related to resistance to the effects of sunk costs and also demonstrates that mindfulness is related to reduced escalation of commitment, an individual's willingness to continue their commitment to an unprofitable course of action through the further investment of resources or time. Overall, trait mindfulness was most consistently related to reduced escalation of commitment, whereas the relationship between trait mindfulness and resistance to the effects of sunk costs was less consistently observed.

A Low-Cost Morris Water Maze for Undergraduate Research: Construction and Demonstration in a Rat Model of Obesity-Induced Diabetes.

The Morris Water Maze (MWM) is a standard task for assessing hippocampal-dependent learning and memory, but the cost of commercial versions of the task may be prohibitive for some undergraduate research projects. We describe the construction of a low-cost MWM for use with rodents and demonstrate the effectiveness of the MWM in a study of the effect of diet-induced obesity on cognitive function in rats. Previous studies have described an impairment in MWM performance in rats fed a high-fat diet combined with streptozotocin injection (to model Type 2 diabetes). We attempted to replicate this finding with our water maze design, and to test the ability of a novel anti-inflammatory treatment to reduce cognitive deficits in the diabetic model. Across five days of hidden-platform training, rats in all groups (normal pellet diet vs. high-fat diet, vehicle vs. treatment) improved on the water maze at similar rates. On a 30-second probe trial, each group showed a preference for the target quadrant used during training. These results did not replicate previous findings that a high-fat diet combined with streptozotocin injections produces deficits in the water maze. However, the results validate the effectiveness of a low-cost water maze ($400 USD) constructed from commonly available materials for hidden platform water maze training. When combined with a low-cost video tracking solution (less than $1,000), we expect this apparatus will be of use to other undergraduate researchers interested in learning and memory.

Post-training cocaine administration facilitates habit learning and requires the infralimbic cortex and dorsolateral striatum.

Human drug addiction is a complex disorder, in which exogenous substances are able to recruit and maintain behaviors involved in drug taking. Many drugs that are addictive in humans are able to act on natural brain systems for learning and memory, and while many memory systems may be affected by addictive drugs, work with operant tasks has shown that addictive drugs (e.g. cocaine and alcohol) are particularly effective in recruiting habit learning systems, compared to natural rewards. It is currently unknown if the ability of addictive drugs to facilitate habit learning depends on a direct action on habit learning systems in the brain, versus the rewarding properties of drug administration. To differentiate between these options, rats were trained to perform two actions (lever pressing), each of which was rewarded with a different natural reward. After acquiring the behavior, rats received three training sessions which were followed by post-training injections of saline or cocaine (5 or 10mg/kg, i.p.). Using sensory-specific satiety, extinction tests revealed that lever pressing for actions which were paired with saline were sensitive to devaluation (typical of goal-directed behaviors) while actions which were paired with cocaine were not sensitive to devaluation (typical of habitual behaviors). Lesions of the infralimbic or dorsolateral striatum were able to block the action of post-training cocaine injections. These data indicate that, within individual rats, cocaine injections facilitate the transition of behavior to habitual control for actions that have been recently performed, without a general facilitation of habit learning, and that this action of cocaine requires brain areas that are critical for learning natural habits.

Sunk cost sensitivity during change-of-mind decisions is informed by both the spent and remaining costs.

Sunk cost sensitivity describes escalating decision commitment with increased spent resources. On neuroeconomic foraging tasks, mice, rats, and humans show similar escalations from sunk costs while quitting an ongoing countdown to reward. In a new analysis taken across computationally parallel foraging tasks across species and laboratories, we find that these behaviors primarily occur on choices that are economically inconsistent with the subject's other choices, and that they reflect not only the time spent, but also the time remaining, suggesting that these are change-of-mind re-evaluation processes. Using a recently proposed change-of-mind drift-diffusion model, we find that the sunk cost sensitivity in this model arises from decision-processes that directly take into account the time spent (costs sunk). Applying these new insights to experimental data, we find that sensitivity to sunk costs during re-evaluation decisions depends on the information provided to the subject about the time spent and the time remaining.

Vicarious Trial-and-Error Is Enhanced During Deliberation in Human Virtual Navigation in a Translational Foraging Task.

Foraging tasks provide valuable insights into decision-making as animals decide how to allocate limited resources (such as time). In rodents, vicarious trial-and-error (back and forth movements), or VTE, is an important behavioral measure of deliberation which is enhanced early in learning and when animals are presented with difficult decisions. Using new translational versions of a rodent foraging task (the "Movie Row" and "Candy Row"), humans navigated a virtual maze presented on standard computers to obtain rewards (either short videos or candy) offered after a variable delay. Decision latencies were longer when participants were presented with difficult offers, overrode their preferences, and when they accepted an offer after rejecting a previous offer. In these situations, humans showed VTE-like behavior, where they were more likely to pause and/or reorient one or more times before making a decision. Behavior on these tasks replicated previous results from the rodent foraging task ("Restaurant Row") and a human version lacking a navigation component ("Web-Surf") and revealed some species differences. Compared to survey measures of delay-discounting, willingness to wait for rewards in the foraging task was not related to willingness to wait for hypothetical rewards. And, smoking status (use of cigarettes or e-cigarettes) was associated with stronger discounting of hypothetical future rewards, but was not well-related to performance on the foraging tasks. In contrast, individuals with overweight or obese BMI (≥25) did not show stronger delay-discounting, but individuals with BMI ≥ 25, and especially females, showed reduced sensitivity to sunk-costs (where their decisions were less sensitive to irrecoverable investments of effort) and less deliberation when presented with difficult offers. These data indicate that VTE is a behavioral index of deliberation in humans, and further support the Movie and Candy Row as translational tools to study decision-making in humans with the potential to provide novel insights about decision-making that are relevant to public health.

Place and response learning in human virtual navigation: behavioral measures and gender differences.

Two experiments examined the use of place and response strategies by humans navigating virtual multiple T mazes. In Experiment 1, probe trials revealed that participants commonly used place and response strategies, and place strategies were more frequent early in training, whereas response strategies were more frequent late in training. Compared with women, men learned the correct path through the maze more quickly and developed a more stable route through the maze. In Experiment 2, participants were trained to locate 2 targets. One target required participants to use either a place or response strategy, whereas the other target could be found using either strategy. Accuracy improved faster for place training compared with response training, and women outperformed men in both groups. Probe trials testing transfer of the imposed strategy to the other target found faster transfer for place training than for response training and that women demonstrated faster transfer than men. Accuracy on probe trials was correlated with poor route stability in the place-trained group and with good route stability in the response-trained group, indicating that navigation strategy use may be related to measures of improvement in performance on normal trials.

Transient striatal gamma local field potentials signal movement initiation in rats.

Transient coherent neural oscillations, as indicated by local field potentials, are thought to underlie key perceptual and cognitive events. We report a transient, state-dependent 50 Hz oscillation recorded from electrodes placed in the striatum of awake, behaving rats. These coherent oscillations, which we term gamma(50), occurred in brief (150 ms) events co-incident with the initiation of movement. On navigation tasks, the animal's speed increased dramatically at the precise moment of the gamma(50) event. This synchronous oscillation may provide a key to understanding striatal function, as well as basal ganglia pathology, which often impairs the control of voluntary movements.

Triple dissociation of information processing in dorsal striatum, ventral striatum, and hippocampus on a learned spatial decision task.

Decision-making studies across different domains suggest that decisions can arise from multiple, parallel systems in the brain: a flexible system utilizing action-outcome expectancies and a more rigid system based on situation-action associations. The hippocampus, ventral striatum, and dorsal striatum make unique contributions to each system, but how information processing in each of these structures supports these systems is unknown. Recent work has shown covert representations of future paths in hippocampus and of future rewards in ventral striatum. We developed analyses in order to use a comparative methodology and apply the same analyses to all three structures. Covert representations of future paths and reward were both absent from the dorsal striatum. In contrast, dorsal striatum slowly developed situation representations that selectively represented action-rich parts of the task. This triple dissociation suggests that the different roles these structures play are due to differences in information-processing mechanisms.

Neuronal activity in the rodent dorsal striatum in sequential navigation: separation of spatial and reward responses on the multiple T task.

The striatum plays an important role in "habitual" learning and memory and has been hypothesized to implement a reinforcement-learning algorithm to select actions to perform given the current sensory input. Many experimental approaches to striatal activity have made use of temporally structured tasks, which imply that the striatal representation is temporal. To test this assumption, we recorded neurons in the dorsal striatum of rats running a sequential navigation task: the multiple T maze. Rats navigated a sequence of four T maze turns to receive food rewards delivered in two locations. The responses of neurons that fired phasically were examined. Task-responsive phasic neurons were active as rats ran on the maze (maze-responsive) or during reward receipt (reward-responsive). Neither maze- nor reward-responsive neurons encoded simple motor commands: maze-responses were not well correlated with the shape of the rat's path and most reward-responsive neurons did not fire at similar rates at both food-delivery sites. Maze-responsive neurons were active at one or more locations on the maze, but these responses did not cluster at spatial landmarks such as turns. Across sessions the activity of maze-responsive neurons was highly correlated when rats ran the same maze. Maze-responses encoded the location of the rat on the maze and imply a spatial representation in the striatum in a task with prominent spatial demands. Maze-responsive and reward-responsive neurons were two separate populations, suggesting a divergence in striatal information processing of navigation and reward.