Fixed-interval responding under second-order schedules of food presentation or cocaine injection.
A quick flash keeps the fixed-interval scallop alive, and cocaine makes it run faster than food.
01Research in Context
What this study did
The team used pigeons in a classic operant chamber. Birds pecked a key under a second-order fixed-interval schedule.
Every 10 minutes the first peck produced a brief light flash. After several flashes the bird got either food or a cocaine shot.
What they found
Cocaine kept the birds pecking faster than food. Both groups still showed the scalloped FI pattern—slow early, fast late.
When the brief flash was taken away, the neat scallop vanished. Response rates flattened and timing fell apart.
How this fits with other research
Gibbon (1967) first showed that a 0.5-s flash alone can hold the FI scallop. Gardner et al. (1977) now adds that drug reinforcers follow the same rule, only faster.
Pomerleau et al. (1973) proved food-paired flashes work as strong conditioned reinforcers. The new study swaps food for cocaine and still keeps the pattern, showing the flash does the heavy lifting.
Kodera et al. (1976) found extra food during the pause barely changes timing. Gardner et al. (1977) shows removing the flash wrecks timing. Together they tell us stimuli, not extra calories, control FI pausing.
Why it matters
If you run token or praise schedules, remember the brief stimulus is the engine. Keep the token, click, or praise brief and consistent. Drop it and the beautiful FI pattern you worked for may flatten out, just like the birds without the flash.
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02At a glance
03Original abstract
Squirrel monkeys operated a key under second-order schedules in which every tenth completion of a 5-minute fixed interval resulted in either presentation of food or intravenous injection of cocaine. When a 2-second light was presented at the completion of the component fixed-interval schedules, positively accelerated responding developed and was maintained in each component. Over a tenfold range of doses of cocaine(30 to 300 microgram/kg/injection) and amounts of food (0.75 to 7.5 g/presentation); the second-order schedule of cocaine injection maintained higher average rates of responding than the second-order schedule of food presentation. Substituting saline for cocaine or eliminating food presentation decreased average rates of responding. When no stimulus change occurred at the completion of the first nine component fixed-interval schedules, but the 2-second light and food presentation or cocaine injection still occurred after the tenth component, only low and relatively constant rates of responding were maintained in each component. Patterns of responding characteristic of 5-minute fixed-interval schedules were maintained by the 2-second light paired with either cocaine injection or food presentation, though the maximum frequency of cocaine injection or food presentation was less than once per 50 minutes.
Journal of the experimental analysis of behavior, 1977 · doi:10.1901/jeab.1977.28-221