Justin N. Wood
To recognize objects quickly and accurately, mature visual systems build invariant object representations that generalize across a range of novel viewing conditions (e.g., changes in viewpoint). To date, however, the origins of this core cognitive ability have not yet been established. To examine how invariant object recognition develops in a newborn visual system, I raised chickens from birth for 2 weeks within controlled-rearing chambers. These chambers provided complete control over all visual object experiences. In the first week of life, subjects’ visual object experience was limited to a single virtual object rotating through a 60° viewpoint range. In the second week of life, I examined whether subjects could recognize that virtual object from novel viewpoints. Newborn chickens were able to generate viewpoint-invariant representations that supported object recognition across large, novel, and complex changes in the object’s appearance. Thus, newborn visual systems can begin building invariant object representations at the onset of visual object experience. These abstract representations can be generated from sparse data, in this case from a visual world containing a single virtual object seen from a limited range of viewpoints. This study shows that powerful, robust, and invariant object recognition machinery is an inherent feature of the newborn brain.
Results from Exps. 1–3. The Upper part of each panel shows the viewpoint range of the imprinted object presented during the input phase. The Lower part of the panel shows the viewpoint ranges of the imprinted object presented during the test phase, along with the percentage of test trials in which the subjects successfully distinguished their imprinted object from the unfamiliar object. Chance performance was 50%. To maximize the pixel-level similarity between the unfamiliar object and the imprinted object, the unfamiliar object (Inset) was always presented from the same viewpoint range as the imprinted object from the input phase in Exps. 1 and 2. In Exp. 3, the unfamiliar object and the imprinted object were presented from the same viewpoint range on each test trial to minimize the pixel-wise image differences between the two test objects and to equate the familiarity of the test animations.