The top protocol is simply a random rate process [random distribution of the dots( = reinforcements) in time]. Subsequent time lines show various predictive relations between the CS and the dots: B. Dots occur only during CSs but at unpredictable times within each CS.This is a random-rate-changeprotocol, that is, the Cs predicts a change in the otherwise random rate of occurrence of reinforcements. C. Some dots also occur when a CS is not present, but they are more likely to occur during the CS than in its absence (“poor positive”). This is called a “poor positive” protocol because the CS is a predictor of the US (the dots, that is, reinforcements), but a poor one. D. Dots occur only during CS and at a fixed time after its onset (almost always, this time is at its offset; in other words, the CS has a fixed duration and dots come at CS offset). This is called delay conditioning. It is the most common protocol. E. Dots occur at a fixed time after CS onset and more often in presence of CS than in its absence. This is a poor positive delay protocol.