ArticlePsychopharmacology2014
Random-ratio schedules produce greater demand for i.v. drug administration than fixed-ratio schedules in rhesus monkeys.
Article in Psychopharmacology, 2014. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 12 papers.
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
12 citing papers in PubMed.
- Preclinical abuse potential testing using behavioral economics and drug self-administration demand-curve analysis: A strategy to improve resolution of drug stratification for regulatory control.Pharmacological reviews · 2026Review
- Unpredictable Drug Access and its Relevance for Substance Use Disorders: A Critical Review.Perspectives on behavior science · 2025Review
- Choice between food and cocaine or fentanyl reinforcers under fixed and variable schedules in female and male rhesus monkeys.Psychopharmacology · 2023Article
- Environmental Uncertainty and Substance Use Disorders: A Behavior Analytic Perspective.Policy insights from the behavioral and brain sciences · 2023Article
- Choice between food and cocaine reinforcers under fixed and variable schedules in female and male rhesus monkeys.Experimental and clinical psychopharmacology · 2023Article
- Unpredictability as a modulator of drug self-administration: Relevance for substance-use disorders.Behavioural processes · 2020Review
- Can Slot-Machine Reward Schedules Induce Gambling Addiction in Rats?Journal of gambling studies · 2019Article
- Reinforcing effects of opioid/cannabinoid mixtures in rhesus monkeys responding under a food/drug choice procedure.Psychopharmacology · 2018Article
- Behavioral economic analysis of the effects of N-substituted benztropine analogs on cocaine self-administration in rats.Psychopharmacology · 2018Article
- Choice between variable and fixed cocaine injections in male rhesus monkeys.Psychopharmacology · 2017Article
- Anxiety sensitivity and smoking variability among treatment seeking smokers.Addictive disorders & their treatment · 2016Article
- Effects of sex and remifentanil dose on rats' acquisition of responding for a remifentanil-conditioned reinforcer.Behavioural pharmacology · 2016Article
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
2 authors.
Funding
Abstract
rationaleOrganisms emit more responses when food is provided according to random as compared with fixed schedules of reinforcement. Similarly, many human behaviors deemed compulsive are maintained on variable schedules (e.g., gambling). If greater amounts of behavior are maintained by drugs of abuse when earned according to variably reinforced schedules, this would suggest that excessive drug-taking behavior may be due in part to the nature of drug availability.
objectivesThe aim was to determine whether random schedules of contingent intravenous drug delivery would produce more responding than similarly priced fixed schedules.
methodsSix rhesus macaque subjects responded to produce cocaine (0.003-0.03 mg/kg/inj), remifentanil (0.01-1.0 μg/kg/inj), or ketamine (0.01-0.1 mg/kg/inj) according to either fixed or random ratio requirements that increased systematically across sessions. Demand curves were generated with the most effective dose of each drug and compared across drug and schedule type.
resultsCocaine and remifentanil maintained higher levels and rates of responding when earned according to random-ratio schedules as compared with fixed-ratio schedules. This difference was most pronounced when drugs were available at high unit prices. Differences in responding across the schedule types generated by ketamine-a lesser-valued reinforcer-were qualitatively similar but smaller in magnitude.
conclusionsThe current study provides a systematic replication across reinforcer type demonstrating that drugs delivered after a random number of responses generate more behavior than those delivered according to a fixed schedule. The variable nature of the availability of drugs of abuse-particularly those that are scarce or expensive-may be a contributing factor to excessive drug intake by humans. This effect is most likely to be observed when more highly demanded (reinforcing) drugs are being consumed.
Indexed as
Identifiers
What OpenQuestion holds
Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.