Impulsivity (choosing a smaller, more immediate reward over a larger, more delayed reward) and substance abuse are positively correlated. It is important to understand how factors like delay to reward and drug effects determine impulsive choice, which can be studied using animal models. This study evaluated impulsive choice in rats, where delays to the larger reward (three food pellets) were presented in decreasing order versus one food pellet delivered immediately. Then, effects of d-amphetamine were assessed. It was found that in three of four rats, d-amphetamine increased impulsive choice when the larger option was presented with decreasing delays. This effect is contrary to what has generally been found with increasing delays. Thus, environmental context can influence drug effects on impulsive choice
