Testing complex animal cognition: Concept learning, proactive interference, and list memory

Wright (2018) ran the same three-step task chain on rhesus monkeys and pigeons.

First came same/different concept learning. Next, a task that creates proactive interference—old items get in the way of new ones. Last, a list-memory test that tracks what is remembered first, middle, and last.

Every bird and monkey saw the same screens, delays, and food pay-offs. The goal was to see who learns faster and remembers longer when everything else is equal.

Monkeys grasped the abstract same/different rule more quickly than pigeons.

They also showed stronger proactive interference; earlier lists slowed new learning.

Their list-memory showed a clear primacy effect—first items stuck longest—while pigeon memory flattened fast.

Szempruch et al. (1993) saw pigeons master conditional discriminations yet fail transitive inference. Wright finds the same birds slower at higher-order concepts, supporting the idea that accurate baseline relations do not guarantee abstract learning.

McLean et al. (1981) boosted monkey memory simply by turning the lights off during delays. Wright keeps lighting constant and still gets long primacy, showing memory durability is not just about visibility.

Epstein (1981) argued pigeons can mimic complex human skills. Wright agrees they can learn, but the data show monkeys do it faster and keep it longer—species ceilings still matter.

If you test relational learning in clients, run the same task chain across people or settings before you call it a deficit. A child who masters matching but fails sequencing may need more exemplars, not more prompts. Use consistent materials and delays; small changes can mask true capacity.