The capability of abstract thought is one of the characteristics that we, humans, want to believe it’s distinguishable in our species. Nevertheless, a recent research developed at Oxford University reveals that newborn ducklings can also be abstract thinkers. We’ve already known that some animals, such as parrots, apes, pigeons and even honey bees, were able to learn relational abstract concepts like “same” and “different”, mainly after experiments using reinforcements. Ducklings, otherwise, seem to be able to differentiate these ideas even when they’re 24 hours old.
Most people are aware that some newborn birds, like ducklings and chicks, have the ability of “imprinting”. This is a process by which newborns learn to identify and then follow around a parent, or the first object they see, touch or hear (such as humans or robots). They follow around the object, as if it were their mother until they become self-sufficient. This behavior might have a great biological adaptive significance, and it is acquired in a few minutes, without training and with high-fidelity. This phenomenon was used by the scientists as a model to understand if ducklings were capable of differentiating “same and different” concepts.
Fig. 1. Newborn ducklings were first exposed to a pair of objects revolving about the center of a training arena, then tested with two novel pairs of objects. (A) Example of a “different shape” training stimulus pair. (B) Example of a “same color” training stimulus pair. After this exposure, the ducklings were tested for their preference between two novel stimulus pairs revolving in apposition. (C) A duckling trained with the set shown in (A) demonstrates its preference for a novel “different shape”’ stimulus over an also-novel “same shape” stimulus. (D) A duckling trained with the stimulus pair shown in (B) approaches a novel “different color” stimulus pair—an incorrect response. (E) The same duckling later in the same trial correctly approaches and closely follows the novel “same color” stimulus.” ( Martinho & Kacelnik (2016). Science 353 (6296), p.286)
Each duckling was exposed for 25 minutes to a moving pair of sample objects, then kept for 30 minutes in the dark, and finally presented to two novel pairs of moving objects. In this final phase, each animal was exposed to two pairs of objects that differed in either color or shape from the first ones, but one of them having a similar pattern of the imprinted objects. For example: in the imprinting phase, one duckling were exposed to a pair of moving red balls. Then, on the final phase of the experiment, it was exposed to a pair of moving purple balls and, at the same time, to a blue linked to an orange ball, moving like a mobile. At this moment, researchers watched ducklings choose which pair of objects to follow. Scientists found that most ducklings preferred to follow objects with a similar pattern of the ones they have previously imprinted, even if they were not exactly the same. In the example above, the duckling would choose to follow the pair of same-color balls, since they were first exposed to a pair of red balls and not a pair of balls that differed in color. The result was similar when the variable characteristic was the shape (watch the video here!).
Fig. 2. The number of ducklings showing preference for the imprinted (left column) or alternative (right column) relation is shown for shape relations in experiment 1 (A) and the same for color relations in experiment 2 (B). Ducklings preferred the imprinted relation in both shape and color, regardless of whether the imprinted relation was “same” or “different.” ( Martinho & Kacelnik (2016). Science 353 (6296), p.287)
This result reveals that animal brain’s learning system does not process information through recognizing only sensorial information, but also by encoding higher-level abstract aspects of stimulus analyses. This ability might be crucial for newborn survival. Even if the “mother” doesn’t seem exactly the same way that she did last time, the duckling can access some abstract information that let it identify her. The ability to comprehend same-different abstract relationships might be crucial for a wider array of vertebrate animals and it might have emerged earlier in life than previous thought. Also, the research suggests that abstract thought is not restricted to humans and animals with big brains, highlighting that it is not what makes humans special.
Bruna de Oliveira Cassettari
Martinho, A. & Kacelnik, A. (2016) Ducklings imprint on the relational concept of “same or different”. Science 353 (6296), 286-288. [doi: 10.1126/science.aaf4247]