Apes Can Match Images Based On Biological Categories
September 11, 2013

Apes Demonstrate Ability To Classify Animals Based On Biological Features

redOrbit Staff & Wire Reports - Your Universe Online

Gorillas and orangutans can categorize images based on various biological categories in much the same way that young human children learn how to tell living beings from inanimate objects or dogs from cats, according to new research appearing in the open-access journal PeerJ.

Scientists have determined that there are at least two ways in which animals can be visually identified as being similar in nature to any other animal: they could be members of the same genus or species, thus closely resembling each other, or they may be evaluated for a different type of criteria (such as a reptile’s lack of fur). The first method searches for perceptual differences, while the other searches for conceptual differences.

There have been many studies examining concept formation in human children, the researchers explained, with great emphasis on the relationship between concept acquisition and language acquisition. Experts have suggested that broader concepts are reliant upon formal scientific training, as well as the ability to form verbal labels for those notions. If non-human animals can represent such concepts, it would be evidence against this hypothesis.

Given the existence of natural categories such as the classifications of animals, the team behind the new study expressed surprise that the language-less, non-human apes had not been observed regarding this phenomenon. Rather, concept-related studies in animals have focused primarily on the perceptual features used by those creatures to extract information about category membership without allowing animals to demonstrate whether or not they are capable of forming concepts at different levels of breadth at the same time.

Led by Dr. Jennifer Vonk, an associate professor at the Oakland University’s Department of Psychology, the researchers analyzed a young female gorilla and four orangutans of various ages. The apes were presented with images of various animals. In one study, the apes were asked to match each one with an image from the same species of family. In another, they were given pictures of animals belonging to different taxonomic classes and asked to match them to sample images of other members of the same class.

In the experiment involving images from the same taxonomic class (i.e. different reptiles or mammals), there were fewer perceptual features, which would theoretically make it harder for the apes to correctly match the images using perceptual strategies. However, Dr. Vonk’s team found that the orangutans were actually able to match pictures from the same groups at a higher level of accuracy than they were able to from within the same species or family.

This discovery indicates that the apes may have developed a concept for animal classes that goes beyond their perceived similarities. Like the orangutans, the gorilla was also able to learn these concepts, but required additional testing than with the concepts involving same-species creatures. The researchers explain that the class level distinctions are analogous to those learned early on during human development.

“The ability of other apes to match stimuli at the level of taxonomic class is a novel finding that tells us that abstract categories can be extracted from visual stimuli in the absence of biological information, verbal labels, or extensive experience with the objects,” Dr. Vonk said. “This finding suggests that orangutans, and perhaps gorillas, may share an underlying conceptual process with humans.”