Inhibitory difficulty can appear in spontaneous behavior as well as on a computer test. A small human study found that abstinent methamphetamine-dependent participants interacted more with unfamiliar objects than comparison participants in a specially arranged room.
Henry and colleagues studied 16 abstinent methamphetamine-dependent adults and 18 matched comparison participants using the human behavior pattern monitor. The room contained engaging objects and no chairs. Participants waited there without explicit instructions about exploring the objects, while behavior was recorded.
The investigators quantified object interactions, time spent interacting and repetitive interactions. They also administered the Wisconsin Card Sorting Test and assessed psychiatric symptoms. Despite its connection to animal research methods, this particular experiment involved humans.
The methamphetamine group showed significantly more total object interactions, more time with objects and more perseverative interactions. Greater interaction was associated with poorer card-sorting performance, higher symptom scores and more frequent methamphetamine use during the preceding year.
These associations make the measure potentially useful for studying behavioral inhibition beyond conventional desk-based testing. They do not establish that curiosity itself is pathological or that any particular exploratory act identifies methamphetamine use.
Participants with positive urine screening results for the listed illicit drugs on the testing day were excluded. The observed behavior therefore should not be presented as a demonstration of acute methamphetamine intoxication. A screening procedure used to characterize a study sample is different from a validated behavioral diagnostic test.
The authors emphasized the small sample, possible nicotine effects and the possibility that inhibitory differences preceded drug use. A cross-sectional comparison cannot establish whether exposure caused a preexisting vulnerability or whether both processes contributed.
The room-based measure has not, through this study, become a roadside impairment test or a method for attributing an individual’s conduct to a drug. Its contribution is a distinct way to study inhibition under defined conditions. The need to separate study populations and outcomes also applies to controlled driving research.