How to test if two tasks measure the same psychological processes related to substance use

What is it about?

A key issue in understanding problems like addiction is identifying what psychological processes contribute to the initiation and continuation of substance use, such as inhibiting desires for immediate rewards (drugs) in favor of long-term goals (sobriety). The better we can quantify these processes using experimental tasks and models of behavior, the better we can predict and eventually prevent substance use. In this article, we develop methods for connecting behavior across different tasks and test whether two different experimental paradigms are measuring the same psychological processes. We show that this method can allow us to get more information about an individual and their propensity for substance use by combining data from two tasks, the delay discounting task and the Cambridge gambling task. When applied to these tasks, our approached showed that both tasks are predictive of substance use in heroin-, amphetamine-, and multiple-substance-dependent individuals. However, the two tasks appear to be measuring different dimensions or subtypes of impulsivity: The delay discounting task measures choice impulsivity, which is related to self-report measures of substance use and propensity to favor rewards that occur sooner in time (as opposed to waiting for long-term rewards); whereas the Cambridge gambling task appears to measure people’s ability to inhibit desires to act immediately, referred to as response inhibition or action impulsivity. This method thus allows us to better understand how different behaviors are related, identifying whether two different tasks or models measure the same or different psychological processes.

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