Dolphins may seek selves in mirror images

In Greek mythology, the lad Narcissus wasted away because he couldn’t bear to stop staring at his reflection in a pool of water. Although people have a stranglehold on such narcissistic pursuits, dolphins recognize their own reflections much as folks do, according to a new study.

A dolphin pauses in front of a mirror in an experimental enclosure. Wildlife Conservation Society

The findings, published in the May 8 Proceedings of the National Academy of Sciences, support a theory that the neural capacity for at least a basic type of self-awareness evolved separately in dolphins and humans.

“We’ve documented a level of self-awareness in bottlenose dolphins that occurs rarely in the animal world,” says psychobiologist Diana Reiss of Columbia University. Reiss conducted the new experiments with psychologist Lori Marino of Emory University in Atlanta.

Before these trials, two captive-raised dolphins had ignored sham ink applications that left no visible marks. After the investigators marked with temporary ink on various parts of the dolphin’s bodies, the animals began perusing the marks by positioning themselves in front of mirrors in their enclosure.

After the dolphins repeatedly viewed reflections of the real ink marks, the researchers repeated the sham marking. This time, the dolphins tried to find mirror images of the sham marks, confirming the presence of a self-aware curiosity, Reiss and Marino argue.

The researchers videotaped the adult dolphins during a series of 30-minute sessions after application of either a visible mark or a later sham. Mark locations varied from one trial to the next. Examples include just above the right eye, behind the top fin, and below the left, bottom fin.

Each dolphin repeatedly maneuvered his body in front of the mirrors to scrutinize visible marks and hunt for ensuing sham marks, the researchers say. This self-directed behavior, including neck stretching and body turning, lasted for periods ranging from 10 seconds to the entire videotaped period.

While searching for marks, the dolphins didn’t display any social behaviors, such as threatening squawks, that might be expected if they regarded the reflection as another dolphin. Moreover, in sessions during which they received no real or sham markings, the dolphins spent little time looking in the mirrors.

In 1970, psychologist Gordon G. Gallup Jr. of the State University of New York at Albany first reported that dye-marked chimpanzees examined the colored spots in mirrors. Some scientists suspect that this reflects unthinking self-recognition, or mistaking of a mirror image for another animal, rather than reflective self-awareness (SN: 1/20/96, p. 42).

That criticism may apply to the dolphin findings as well, Gallup comments. “The new dolphin findings are interesting but not definitive,” he says. An earlier, less widely noticed study of mirror looking by marked dolphins also indicated that dolphins recognize themselves, but Gallup considers the methodology of the new study to be more sophisticated.

Janet Mann of Georgetown University in Washington, D.C., who studies wild dolphins, says that it’s no surprise that dolphins recognize themselves in mirrors. Still, in her view, it’s unclear what this reveals about dolphins’ mental lives.

Wild dolphins exhibit behavior indicative of self-awareness (SN: 10/28/00, p. 284). Gallup and Mann both say that scientists need to probe for self-awareness in complex situations, such as by looking for deception among dolphins.

In the wild, for instance, Mann has observed an adult female being surrounded by three aggressive males and seeking refuge in an all-female group. Some of the females rubbed against the hovering males and stroked them with their fins, diverting attention. Another female blocked the males’ view of the escapee and escorted her until she could safely dart off. At that point, the males seemed to recognize that they’d been duped. After vainly searching for their quarry, the trio attacked the escort.

Bruce Bower has written about the behavioral sciences for Science News since 1984. He writes about psychology, anthropology, archaeology and mental health issues.