On 2014 Dec 16, Serge Ahmed commented:

This review provides a nuanced and intelligent summary of the research on drug habits from the UK “Cambridge School” of Neuropsychology. It reminds us several obvious, albeit too often overlooked, facts about drug habits. First, drug habits, like other habits, develop in stationary and thus highly predictable environments; much less so in changing environments. Second, drug habits per se are adaptive behaviors and their formation is generally not pathological. Third, in theory, drug habits may become pathological only when they escape to the control of the drug user (i.e., self-control), be it a human or a non-human animal. Loss of self-control entails that the drug user attempts to stop or reduce drug use, generally to avoid or minimize the negative consequences, but with no or little success. Finally and most importantly, this review helps us to better realize that there is still no direct evidence that experimental animals have lost control over their drug seeking and/or taking habits. There is only evidence in some individual animals that drug habits can partly escape to the control of the experimenter. For instance, an individual rat that continues to seek cocaine despite punishment can be considered to have escaped to the control of the experimenter (perhaps because the punishment is too weak) but not necessarily to its own self-control. In my view, this important distinction between these different sources of control (self versus others) should be better appreciated by researchers who attempt to model addiction in animals.

On 2014 Dec 16, Serge Ahmed commented:

This review provides a nuanced and intelligent summary of the research on drug habits from the UK “Cambridge School” of Neuropsychology. It reminds us several obvious, albeit too often overlooked, facts about drug habits. First, drug habits, like other habits, develop in stationary and thus highly predictable environments; much less so in changing environments. Second, drug habits per se are adaptive behaviors and their formation is generally not pathological. Third, in theory, drug habits may become pathological only when they escape to the control of the drug user (i.e., self-control), be it a human or a non-human animal. Loss of self-control entails that the drug user attempts to stop or reduce drug use, generally to avoid or minimize the negative consequences, but with no or little success. Finally and most importantly, this review helps us to better realize that there is still no direct evidence that experimental animals have lost control over their drug seeking and/or taking habits. There is only evidence in some individual animals that drug habits can partly escape to the control of the experimenter. For instance, an individual rat that continues to seek cocaine despite punishment can be considered to have escaped to the control of the experimenter (perhaps because the punishment is too weak) but not necessarily to its own self-control. In my view, this important distinction between these different sources of control (self versus others) should be better appreciated by researchers who attempt to model addiction in animals.