Mind the gap: means–end discrimination by pigeons

Four experiments examined the discrimination performance of four pigeons in two means–end tasks. The pigeons were required to discriminate between two ribbon/food dish assemblies in a simultaneous discrimination. In the connected condition, the ribbon was attached to an out-of-reach food dish, allowing it to be retrieved by the pigeon pulling it with its beak. In the unconnected condition, the ribbon was unattached to the dish, preventing it from being used to retrieve the food. In experiment 1, the pigeons learned this means–end task in fewer than 160 trials. Experiment 2 established that this discrimination was controlled by the gap between the ribbon and dish, and, to a limited extent, by the ribbon's colour. Experiment 3 showed no transfer of this prior means–end training to a second means–end task using a different physical arrangement of ‘connectedness’. Experiment 4 revealed that control of this second task was also related to the perceptual features of the gap between the ribbons. The results indicate that the pigeons did not comprehend the conceptual nature of connectedness across these means–end tasks, but did successfully learn each discrimination based on its relevant perceptual features.