Breakdown of Will

Short Abstract Behavioral science has long been puzzled by the experience of temptation, the resulting impulsiveness, and the variably successful control of this impulsiveness. Breakdown of Will Ainslie--Breakdown of Will 3 Long Abstract Behavioral science has long been puzzled by the experience of temptation, the resulting impulsiveness, and the variably successful control of this impulsiveness. In conventional theories a governing faculty like the ego evaluates future choices consistently over time, discounting their value for delay exponentially, that is, by a constant rate; impulses arise when this ego is confronted by a conditioned appetite. Breakdown of Will (Ainslie, 2001) presents evidence that contradicts this model. Both people and nonhuman animals spontaneously discount the value of expected events in a curve where value is divided approximately by expected delay, a hyperbolic form that is more bowed than the rational, exponential curve. With hyperbolic discounting, options that pay off quickly will be temporarily preferred to richer but slower-paying alternatives, a phenomenon that, over times on the order of days, can account for impulsive behaviors, and over periods of fractional seconds can account for involuntary behaviors. Contradictory reward-getting processes can in effect bargain with each other, and stable preferences can be established by the perception of recurrent choices as test cases (precedents) in recurrent intertemporal prisoner's dilemmas. The resulting motivational pattern resembles traditional descriptions of the will, as well as of compulsive phenomena that can now be seen as side-effects of will: overconcern with precedent, intractable but circumscribed failures of self-control, a motivated ("dynamic") unconscious, and an inability to exploit emotional rewards. Hyperbolic curves also suggest a means of reducing classical conditioning to motivated choice, the last necessary step for modeling many involuntary processes like emotion and appetite as reward-seeking behaviors; such modeling in turn provides a rationale for empathic reward and the "construction" of reality

Studies of access for minimally invasive surgery

Introduction: The advantages of laparoscopic cholecystectomy over open cholecystectomy are now well established. Nevertheless, small changes in technique and careful attention to detail can result in further improvements in clinical outcome. The aim of this thesis was to apply this concept to studies of the trocar and cannula system used to gain access to the peritoneum. Methods and Results: Patients were randomised to conventional laparoscopic cholecystectomy (CLC) or micropuncture laparoscopic cholecystectomy (MPLC, three 3.3mm, one 10mm cannulae). The duration of each operative stage and the procedure were recorded. Interleukin-6, adrenocorticotropic hormone (ACTH) and vasopressin were sampled for 24 hours. Pain scores and analgesic consumption were recorded for one week. Pulmonary function and quality of life (EQ-5D) were monitored for four weeks. Forty patients participated. Groups were comparable for age, duration of symptoms and indications for surgery. Total operative time was similar but the time to clip the cystic duct after cholangiography was significantly longer for MPLC. Significantly fewer patients required postoperative parenteral opiates in the MPLC group but oral analgesic consumption was similar in both groups. Median pain scores were lower at all time points for MPLC but this was not statistically significant. There were no significant differences in interleukin-6, ACTH or vasopressin responses, pulmonary function or EQ-5D scores. The purpose of the second study was to compare the maximum depth of penetration of the peritoneal cavity by the tips of pyramidal, sharp conical and blunt conical trocars. Sections of abdominal wall from pigs were stretched across a jig so that the skin and peritoneal surfaces could be visualised. Each trocar was inserted ten times by hand and then with a mechanical device. The findings were similar for trocar s inserted by hand or the mechanical device. In the third study, the incidence and characteristics of injury sustained by the bowel, when impinged by pyramidal, sharp conical and blunt conical trocars were compared. Rates of deflection were also recorded. Pyramidal trocars caused stellate penetrating injuries and the sharp conical trocars, small round puncture wounds. The bowel did not deflect upon contact with either the pyramidal or the sharp conical trocar. The blunt conical trocars however, was more likely to cause deflection, never breached the serosa and only created a small round "dimple." These differences were all statistically significant. Conclusions: Diameter of trocar Cholecystectomy using smaller trocars, cannulae and instruments is widely applicable to elective cholecystectomy in a westernised population. Although the change from a 10mm to a 3mm laparoscope increased the time to clip and divide the cystic duct and artery, this had no impact on the overall time of the procedure. Despite a reduction in the consumption of parenteral analgesia among the patients in the micropuncture group, there was no corresponding reduction in pain scores. Overall, this study found no evidence that fine calibre instruments conferred any obvious major clinical benefits to the patients. Profile of the trocar Pyramidal trocars encroach less into the abdominal cavity during the process of insertion, but will injure bowel or aorta upon contact. Sharp conical trocars depress the abdominal wall to a greater extent before they facilitate entry of the cannula and will injure bowel or aorta upon contact. Blunt conical trocars require to be inserted to the same depth as sharp conical trocars but are unlikely to traumatise bowel. They can deflect aorta and are less likely to cause injury than trocars with a sharp tip. It is not clear whether the risk of injury fi om a pyramidal trocar that facilitates entry of the cannula with less depression of the abdominal wall is safer than a blunt conical trocar' that encroaches further into the abdomen but is less likely to cause injury should it contact bowel or aorta. However, it can be deduced that blunt conical trocars are unlikely to cause injury if bowel is inadvertently contacted during open or closed access. Trocars with a sharp tip should probably be avoided. (Abstract shortened by ProQuest.)

Do People Bundle Sequences of Choices? An Experimental Investigation

Economists and psychologists have sought to model and explain both impulsive behavior and the costly but often successful mechanisms by which people control it. Ainslie [1975][1992][2001] suggests that self-control is often achieved on account of a phenomenon he calls “choice bundling.” This refers to re-framing of series of discrete choices as single choices over whole series. Whereas other core elements of Ainslie’s account of self-regulation, such as hyperbolic discounting and intrapersonal bargaining among temporally distinguished selves have been subject to extensive modeling by economists, choice bundling has been absent from the economic literature because it has never been empirically isolated in a controlled setting that meets the methodological requirements of the discipline. We report a laboratory experiment that fills this gap. Subjects made choices between smaller, sooner and larger, later real monetary rewards under experimental treatments that allowed us to discriminate between choice bundling, reliance on pre-commitment, and possible magnitude effects on intertemporal discounting. Risk preference measures were used to obtain accurate discounting estimates, based on estimation of mixture models that incorporate exponential, hyperbolic and quasi-hyperbolic discounting functions. We use structural econometric procedures which are well established in the literature on binary choice and find strong support for the hypothesis that subjects bundled choices when conditions allowed them to do so, and consequently exhibited different discounting behavior in these conditions

Reduced blood flow through intrapulmonary arteriovenous anastomoses at rest and during exercise in lowlanders during acclimatization to high altitude

Blood flow through intrapulmonary arteriovenous anastomoses (QIPAVA ) is elevated during exercise at sea level (SL) and at rest in acute normobaric hypoxia. Following high altitude (HA) acclimatization, resting QIPAVA is similar to SL, but it is unknown if this is true during exercise at HA. We reasoned that exercise at HA (5,050 m) would exacerbate QIPAVA due to heightened pulmonary arterial pressure. Using a supine cycle ergometer, seven healthy adults free from intracardiac shunts underwent an incremental exercise test at SL (25, 50, 75% of SL VO2peak ) and at HA (25, 50% of SL VO2peak ). Echocardiography was used to determine cardiac output (Q) and pulmonary artery systolic pressure (PASP) and agitated saline contrast was used to determine QIPAVA (bubble score; 0-5). The principal findings were: (1) Q was similar at SL-rest (3.9 +/- 0.47 l min-1 ) compared with HA-rest (4.5 +/- 0.49 l min-1 ; P = 0.382), but increased from rest during both SL and HA exercise (P < 0.001); (2) PASP increased from SL-rest (19.2 +/- 0.7 mmHg) to HA-rest (33.7 +/- 2.8 mmHg; P = 0.001) and, compared with SL, PASP was further elevated during HA exercise (P = 0.003); (3) QIPAVA was increased from SL-rest (0) to HA-rest (median = 1; P = 0.04) and increased from resting values during SL exercise (P < 0.05), but were unchanged during HA exercise (P = 0.91), despite significant increases in Q and PASP. Theoretical modeling of microbubble dissolution suggests that the lack of QIPAVA in response to exercise at HA is unlikely caused by saline contrast instability

A test of financial incentives to improve warfarin adherence

<p>Abstract</p> <p>Background</p> <p>Sub-optimal adherence to warfarin places millions of patients at risk for stroke and bleeding complications each year. Novel methods are needed to improve adherence for warfarin. We conducted two pilot studies to determine whether a lottery-based daily financial incentive is feasible and improves warfarin adherence and anticoagulation control.</p> <p>Methods</p> <p>Volunteers from the University of Pennsylvania Anticoagulation Management Center who had taken warfarin for at least 3 months participated in either a pilot study with a lottery with a daily expected value of $5 (N = 10) or a daily expected value of$3 (N = 10). All subjects received use of an Informedix Med-eMonitor™ System with a daily reminder feature. If subjects opened up their pill compartments appropriately, they were entered into a daily lottery with a 1 in 5 chance of winning $10 and a 1 in 100 chance of winning$100 (pilot 1) or a 1 in 10 chance of winning $10 and a 1 in 100 chance of winning$100 (pilot 2). The primary study outcome was proportion of incorrect warfarin doses. The secondary outcome was proportion of INR measurements not within therapeutic range. Within-subject pre-post comparisons were done of INR measurements with comparisons with either historic means or within-subject comparisons of incorrect warfarin doses.</p> <p>Results</p> <p>In the first pilot, the percent of out-of-range INRs decreased from 35.0% to 12.2% during the intervention, before increasing to 42% post-intervention. The mean proportion of incorrect pills taken during the intervention was 2.3% incorrect pills, compared with a historic mean of 22% incorrect pill taking in this clinic population. Among the five subjects who also had MEMS cap adherence data from warfarin use in our prior study, mean incorrect pill taking decreased from 26% pre-pilot to 2.8% in the pilot. In the second pilot, the time out of INR range decreased from 65.0% to 40.4%, with the proportion of mean incorrect pill taking dropping to 1.6%.</p> <p>Conclusion</p> <p>A daily lottery-based financial incentive demonstrated the potential for significant improvements in missed doses of warfarin and time out of INR range. Further testing should be done of this approach to determine its effectiveness and potential application to both warfarin and other chronic medications.</p

Mechanisms of impulsive choice: I. Individual differences in interval timing and reward processing

Impulsive choice behavior incorporates the psychological mechanisms involved in the processing of the anticipated magnitude and delay until reward. The goal of the present experiment was to determine whether individual differences in such processes related to individual differences in impulsive choice behavior. Two groups of rats (Delay Group and Magnitude Group) were initially exposed to an impulsive choice task with choices between smaller-sooner (SS) and larger-later (LL) rewards. The Delay Group was subsequently exposed to a temporal discrimination task followed by a progressive interval task, whereas the Magnitude Group was exposed to a reward magnitude sensitivity task followed by a progressive ratio task. Inter-task correlations revealed that the rats in the Delay Group that made more self-controlled (LL) choices also displayed lower standard deviations in the temporal bisection task and greater delay tolerance in the progressive interval task. Impulsive choice behavior in the Magnitude Group did not display any substantial correlations with the reward magnitude sensitivity and progressive ratio tasks. The results indicate the importance of core timing processes in impulsive choice behavior, and encourage further research examining the effects of changes in core timing processes on impulsive choice