Table 1. Sequence of conditions arranged in Experiments 1 and 2. Components changed after 10 food deliveries: Thus, when eight magazine-light presentations per component were arranged, components changed after an average of 18 events (food or magazine light). The value of r in Experiment 2 is the correlation of magazine-light and green-keylight presentation ratios with food ratios.

Condition	Arranged number of magazine-light presentations per component
Experiment 1
1	0
2	2
3	4
4	6
5	8
Experiment 2	Correlation (r) between magazine light ratios, and green keylight ratios, with food ratios
6	Magazine light r  =  −1.0
7	Magazine light r  =  0
8	Magazine light r  =  +1.0; Green keylights r  =  −1.0
9	Magazine light r  =  −1.0; Green keylights r  =  +1.0