Summary of Experiment 2 Design.

When three stimuli are listed (e.g., DEF+), 2nd-order occasion setting is hypothesized to be learned (except for DES- and UMS-). When two stimuli are listed (e.g., EF-), 1st-order occasion setting is hypothesized to be learned. When one stimulus is presented (e.g., F+), direct associative learning is hypothesized to be learned. All stimuli within a trial were presented serially. "+" indicates reinforcement; "-" indicates no reinforcement; "OS2" indicates 2nd-order occasion setting; "OS1" indicates 1st-order occasion setting; "Direct" indicates direct associative learning. Notably, the "DEF" family was trained in 2nd-order occasion setting before Transfer Test 1 and 2; the "UMN" family was only trained in 1st-order occasion setting before Transfer Test 1 but was trained in 2nd-order occasion setting before Transfer Test 2. This allowed the examination of whether "D" was indeed a 2nd-order occasion setter by testing "D" with "MN" before and after "MN" was trained with 2nd-order occasion setter "U." We predicted "D" would affect "MN" more strongly after "MN" was trained with "U" than before that training.