On 2014 Jun 17, Serge Ahmed commented:

Imagine that a rat has come to expect a limited daily access time to a desired good and that it has no way to save it for future consumption. Intuitively, you might think that the shorter the expected access time to the good, the faster the rat will consume it. In other words, the rate of consumption should be inversely related to the daily access time to the good (at least within a certain range of time values).

In this elegant study, the authors report the opposite outcome in rats self-administering cocaine. Rats did not self-administer cocaine at a lower rate but instead at a higher rate when they expected a long (6h) versus short (1h) daily access time to the drug. Importantly, when rats had no way to predict whether access time to the drug will be short or long, they self-administered cocaine as if they were expecting a short access time!

How to make sense of these rather unexpected findings? To address this question, we will probably have to address first the following other questions: Is the positive relationship between rate of consumption and access time reported in this study TYPICALLY observed with other goods or is it specific to cocaine self-administration? What does this relationship tell us about how and what do rats exactly learn in this sort of differential access time setting? Does it imply that rats have a longer future time horizon than previously thought (i.e., hours instead of minutes)? I hope that future research will shed some light on these different questions.

On 2014 Jun 17, Serge Ahmed commented:

Imagine that a rat has come to expect a limited daily access time to a desired good and that it has no way to save it for future consumption. Intuitively, you might think that the shorter the expected access time to the good, the faster the rat will consume it. In other words, the rate of consumption should be inversely related to the daily access time to the good (at least within a certain range of time values).

In this elegant study, the authors report the opposite outcome in rats self-administering cocaine. Rats did not self-administer cocaine at a lower rate but instead at a higher rate when they expected a long (6h) versus short (1h) daily access time to the drug. Importantly, when rats had no way to predict whether access time to the drug will be short or long, they self-administered cocaine as if they were expecting a short access time!

How to make sense of these rather unexpected findings? To address this question, we will probably have to address first the following other questions: Is the positive relationship between rate of consumption and access time reported in this study TYPICALLY observed with other goods or is it specific to cocaine self-administration? What does this relationship tell us about how and what do rats exactly learn in this sort of differential access time setting? Does it imply that rats have a longer future time horizon than previously thought (i.e., hours instead of minutes)? I hope that future research will shed some light on these different questions.