When a pigeon's pecks on two keys were reinforced concurrently by two independent
variable‐interval (VI) schedules, one for each key, the response rate on either key was given …

When a pigeon's pecking on a single key was reinforced by a variable‐interval (VI) schedule
of reinforcement, the rate of pecking was insensitive to changes in the duration of …

In an analysis of interactions between concurrent performances, variable‐interval
reinforcement was scheduled, in various sequences, for both keys, for only one key, or for …

In a two‐key pigeon chamber, variable‐interval reinforcement was scheduled for a specified
number of pecks, emitted either on a single key or in a particular sequence on the two keys …

Pigeons' key pecks were maintained by variable‐ratio or variable‐interval schedules of food
reinforcement. For pairs of pigeons in one group, variable‐ratio reinforcement was arranged …

Two pigeons were trained to peck a key under several multiple variable‐interval variable‐
interval schedules of reinforcement; different numbers of reinforcements were scheduled in …

Six pigeons were trained on multiple and concurrent schedules. The reinforcement rates
were varied systematically (a) when lever pressing was required in one component and key …

Pigeons' pecks on each of two concurrently available response keys were reinforced under
a variable‐interval schedule that sometimes allotted food‐pellet deliveries to one key and …

Pigeons were exposed to two equal, concurrent variable‐interval schedules of
reinforcement on two response keys. One key was continuously illuminated. Pecking on that …

A comparison was made of the effects of variable‐interval, variable‐time, and tandem
variable‐interval fixed‐time schedules on key‐peck responding of pigeons. The variable …