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Biomedical subjects

George Ainslie

Publications and source records attributed to George Ainslie.

6 recordsLinked to original sources
PubMed2007

Frontoparietal cortical activity of methamphetamine-dependent and comparison subjects performing a delay discounting task.

Relative to individuals who do not have addictive disorders, drug abusers exhibit greater devaluation of rewards as a function of their delay ("delay discounting"). The present study sought to extend this finding to methamphetamine (MA) abusers and to help understand its neural basis. MA abusers (n = 12) and control subjects who did not use illicit drugs (n = 17) participated in tests of delay discounting with hypothetical money rewards. We then used a derived estimate of each individual's delay discounting to generate a functional magnetic resonance imaging probe task consisting of three conditions: "hard choices," requiring selections between "smaller, sooner" and "larger, later" alternatives that were similarly valued given the individual's delay discounting; "easy choices," in which alternatives differed dramatically in value; and a "no choice" control condition. MA abusers exhibited more delay discounting than control subjects (P < 0.05). Across groups, the "hard choice > no choice" contrast revealed significant effects in the ventrolateral prefrontal cortex, dorsolateral prefrontal cortex (DLPFC), dorsal anterior cingulate cortex, and areas surrounding the intraparietal sulcus (IPS). With group comparisons limited to these clusters, the "hard choice > easy choice" contrast indicated significant group differences in task-related activity within the left DLPFC and right IPS; qualitatively similar nonsignificant effects were present in the other clusters tested. Whereas control subjects showed less recruitment associated with easy than with hard choices, MA abusers generally did not. Correlational analysis did not indicate a relationship between this anomaly in frontoparietal recruitment and greater degree of delay discounting exhibited by MA abusers. Therefore, while apparent inefficiency of cortical processing related to decision-making in MA abusers may contribute to the neural basis of enhanced delay discounting by this population, other factors remain to be identified.

Adult↗
PubMed2006

The behavioral economics of will in recovery from addiction.

Behavioral economic studies demonstrate that rewards are discounted proportionally with their delay (hyperbolic discounting). Hyperbolic discounting implies temporary preference for smaller rewards when they are imminent, and this concept has been widely considered by researchers interested in the causes of addictive behavior. Far less consideration has been given to the fact that systematic preference reversal also predicts various self-control phenomena, which may also be analyzed from a behavioral economic perspective. Here we summarize self-control phenomena predicted by hyperbolic discounting, particularly with application to the field of addiction. Of greatest interest is the phenomenon of choice bundling, an increase in motivation to wait for delayed rewards that can be expected to result from making choices in whole categories. Specifically, when a person's expectations about her own future behavior are conditional upon her current behavior, the value of these expectations is added to the contingencies for the current behavior, resulting in reduced impulsivity. Hyperbolic discounting provides a bottom-up basis for the intuitive learning of choice bundling, the properties of which match common descriptions of willpower. We suggest that the bundling effect can also be discerned in the advice of 12-step programs.

Behavior Therapy↗
PubMed2005

Précis of Breakdown of Will.

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 periods from minutes to 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: over-concern 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.

Animals↗
PubMed2003

Uncertainty as wealth.

Emotional satisfaction cannot be increased above "normal"-the same normal as the caveman's-for any length of time, but the wealth and consumption style of modern civilization may systematically reduce some people's satisfaction below normal. Hyperbolic discounting of delayed, expected rewards suggests causes for this reduction in humans, and for how we often respond to it, while conventional exponential discounting does not. Hyperbolic discounting has been well demonstrated by four experimental routes; and there is moderate evidence that it motivates impulse control by an intertemporal bargaining technique, proposed as the mechanism of willpower.A theoretical model is described in which emotion is a reward-dependent behavior rather than a stimulus-bound respondent. Positive emotion is then limited by premature satiation of the appetite for it, a relentless process motivated by the impatience that is described by hyperbolic discount curves. This satiation can be restrained only by using adequately rare and unpredictable occasions as cues for the emotion. Willpower not only is helpless against the urge for premature satiation, but it exacerbates the satiation problem by making anticipation more thorough. The result is an asymmetrical contest between systematic attempts to vouchsafe satisfying events and impetuous attempts to put them at risk. Despite their adversarial relationship, both may to some extent be in the person's long range interest.

Journal Article↗
PubMed2003

Building blocks of self-control: increased tolerance for delay with bundled rewards.

Impulsive choice can be defined as temporary preference for a smaller-sooner reward (SS) over a larger-later reward (LL). Hyperbolic discounting implies that impulsive choices will occur less when organisms choose between a series of SSs versus LLs all at once than when they choose between single SS versus LL pairs. Eight rats were exposed to two conditions of an intertemporal choice paradigm using sucrose solution as reward. In both conditions, the LL was 150 microl delayed by 3 s, while the SS was an immediate reward that ranged from 25-150 microl across sessions. Preference for the LL was greater when the chosen reward was automatically delivered three times in succession (bundled) than when it was chosen singly and delivered after each choice. For each of the 8 rats, the estimated SS amount that produced indifference was higher in the bundled condition than in the single condition. Because bundling in humans may be based on the perception that one's current choice is predictive of future choices, the data presented here may demonstrate an important building block of self-control.

Animals↗