Newborn chickens generate invariant object representations at the onset of visual object experience

Abstract

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.

Keywords: animal cognition; avian cognition; imprinting; newborn cognition.

Fig. 1.

(A) The interior of a controlled-rearing chamber. The front wall (removed for this picture) was identical to the back wall. (B) A young chicken with one of the virtual objects.

Fig. 2.

A schematic showing the presentation schedule of the virtual objects on the two display walls. This schedule shows a 4-h period from (A) the input phase and (B) the test phase during Exp. 1. These subjects were imprinted to object A in the input phase, with object B serving as the unfamiliar object in the test phase.

Fig. 3.

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.

Fig. 4.

Performance of each individual subject (ordered by performance). The graphs show the total number of correct and incorrect test trials for each subject across the test phase. P values denote the statistical difference between the number of correct and incorrect test trials as computed through one-tailed binomial tests.