An instance of viewpoint consistency in pigeon object recognition.

Pigeons were trained on a visual discrimination, a task using a TV monitor. Two different types of stimuli appeared as pictures on the TV screen, one was a feeder used in their home cages and the other a coffee mug. One group of the pigeons was trained to peck the screen when the feeder appeared on it, while the other group was trained to peck the screen when the mug appeared. The feeder was considered to be a `familiar object' but the mug an `unfamiliar object' for the subjects. After training, to peck the familiar object, the subjects showed generalization to unusual view pictures of the object, but they did not show such generalization after training to peck the unfamiliar object. These results suggest that view point consistency is limited to familiar objects in pigeons.