Discriminative stimulus effects of diazepam and buspirone in normal volunteers.
Money rewards can make people notice tiny drug effects they would otherwise miss.
01Research in Context
What this study did
Researchers gave healthy adults two pills: diazepam (a calming drug) and buspirone (an anti-anxiety drug).
People had to learn which pill they took by pressing the correct button. Correct presses earned money.
The team also tested if smaller, harder-to-feel doses could still be noticed when money was on the line.
What they found
Everyone learned to tell the pills apart when the normal dose was used.
When the training started with tiny doses, people still figured it out and the whole dose-response curve shifted left.
Money rewards made even weak drug cues easy to spot.
How this fits with other research
Martens et al. (1989) and Bickel et al. (1991) showed diazepam usually hurts learning new button sequences. This study seems opposite: people got better at noticing the drug. The difference is the task. Earlier work tested memory; this one tested simple detection.
Dougherty et al. (1996), Carr et al. (2002), and Lancioni et al. (2000) used concurrent schedules with pigeons or rats. Gaylord-Ross et al. (1995) moved the same design to humans and still got clean, graded curves, proving the method crosses species.
Thompson (1975) first showed sedatives flatten learning curves in animals. The 1995 human data add a twist: reinforcement can reverse the blunting effect when the job is just to notice, not to master a chain.
Why it matters
If you run drug-education or safety programs, remember that rewards can make weak internal cues obvious. This may help clients notice and report side-effects early. Try adding small, immediate incentives when you need people to detect subtle physical or emotional changes.
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02At a glance
03Original abstract
A within-subject design was used to characterize the effects of dose manipulations on discriminative and self-reported effects of oral diazepam and buspirone. Subjects were trained to discriminate diazepam (10 mg) versus placebo (n = 10), or buspirone (10 or 15 mg) versus placebo (n = 9). The compounds were identified to subjects by letter code before discrimination training began. In later sessions, correct identifications at 2 hr after the oral administration of drug earned money. All subjects showed accurate discrimination performance during the test-of-acquisition phase. In a low-dose generalization phase, diazepam and buspirone produced dose-related increases in drug identifications across a four-fold range of doses. In a subsequent low-dose training phase, in which subjects were trained to discriminate progressively lower drug doses, the median lowest discriminable dose of diazepam and buspirone was 2.5 and 7.5 mg, respectively. Dose-response functions for drug identifications were shifted leftward in the low-dose training phase relative to the low-dose generalization phase, suggesting that reinforcement of progressively lower doses enhances drug discriminability. The self-reported effects of diazepam and buspirone were similar (e.g., both drugs increased ratings of drug strength and clumsy/uncoordinated) and different (e.g., diazepam but not buspirone increased ratings of drowsy/sleepy; buspirone but not diazepam increased ratings of tense/nervous). This study demonstrates discriminative and self-reported effects of diazepam and buspirone at doses lower than previously shown to be behaviorally active, and suggests that at commonly used clinical doses, diazepam is relatively more discriminable than buspirone.
Journal of the experimental analysis of behavior, 1995 · doi:10.1901/jeab.1995.63-277