Direct and relational representation during transitive list linking in pinyon jays (Gymnorhinus cyanocephalus).

The authors used the list-linking procedure (Treichler & Van Tilburg, 1996) to explore the processes by which animals assemble cognitive structures from fragmentary and often contradictory data. Pinyon jays (Gymnorhinus cyanocephalus) were trained to a high level of accuracy on 2 implicit transitive lists, A > B > C > D > E and 1 > 2 > 3 > 4 > 5. They were then given linkage training on E > 1, the single pair that linked the 2 lists into a composite, 10-item hierarchy. Following linkage training, the birds were tested on nonadjacent probe pairs drawn both from within (B-D and 2-4) and between (D-1, E-2, B-2, C-3) each original list. Linkage training resulted in a significant transitory disruption in performance, and the adjustment to the resulting implicit hierarchy was far from instantaneous. Detailed analysis of the course of the disruption and its subsequent recovery provided important insights into the roles of direct and relational encoding in implicit hierarchies.