Echolocation Touch

Dolphins' echolocation may be more like feeling than like seeing

- Cody Cottier

IT'S MIDNIGHT in a pitch-dark parking lot. Trying to unlock your car, you fumble and drop the keys. You squat down and run your hand across the invisible pavement. To the left you feel a firm, rubbery tire. Reversing course, you pass over jagged pebbles and papery leaves. Finally your fingers discover—and instantly close around—a notched piece of metal. This kind of tactile exploration may be the closest we can get to imagining the experience of dolphin echolocation, say the authors of a study on dolphin brains that was recently published in PLOS One.

People often imagine echolocation as "seeing" with sound-experiencing auditory signals as a world of images like the ones our brains typically create from light perceived by our eyes. Like sonar devices, which turn sonic waves into visual representations, echolocators emit sounds and then decode spatial and textural information in the echoes that bounce back. And when Russian scientists inserted electrodes into the heads of dolphins and porpoises in the 1970s and 1980s, they reported detecting brain activity in the visual cortex while the animals heard sounds.