Behavioral effects of caffeine, methamphetamine, and methylphenidate in the rat.
Fixed-interval and fixed-number schedules turn stimulants into readable behavior fingerprints.
01Research in Context
What this study did
Scientists gave rats three different stimulants: caffeine, methamphetamine, or methylphenidate.
The rats worked under fixed-interval and fixed-number schedules for food.
Each drug created its own unique pattern of pressing, like a fingerprint.
What they found
Caffeine, methamphetamine, and methylphenidate each changed responding in a special way.
The patterns let the team tell which drug was on board just by looking at the data.
Fixed-interval and fixed-number schedules acted like a drug test built from lever presses.
How this fits with other research
Sievert et al. (1988) later used the same fixed-interval setup.
They showed cocaine makes rates uniform while pentobarbital only slows them down, extending the fingerprint idea to a new pair.
Keel et al. (1997) moved from FI/FN to fixed-consecutive-number schedules.
All abused drugs broke accurate runs, proving the method works across schedule types.
Barber et al. (1977) added a pause rule to FI.
They found low rates go up and high rates go down with pentobarbital, confirming baseline rate shapes drug effects first seen in 1963.
Why it matters
You can use simple steady schedules to spot how stimulants change behavior.
If a client’s response pattern shifts after a new ADHD med, compare pre- and post-drug FI data.
The same lever-press fingerprint that separated caffeine from methamphetamine in rats can help you judge whether a prescription is working in humans.
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02At a glance
03Original abstract
It was possible to distinguish three closely-related psychomotor stimulants, caffeine, methamphetamine, and methylphenidate, by means of two operant behavior procedures, fixed interval and fixed number. Under the fixed interval procedure, the percentage change in the number of R(B)s per reinforcement was significantly smaller with caffeine than with methamphetamine or methylphenidate (p < .001). Under the fixed number procedure, the percentage change was significantly smaller with methamphetamine than with caffeine or methylphenidate (p < .001). Thus, methylphenidate had a methamphetamine-like effect under fixed interval and a caffeine-like effect under fixed number.
Journal of the experimental analysis of behavior, 1963 · doi:10.1901/jeab.1963.6-331