People have a sharp no-fly zone around their faces. Though its boundaries depend on the person, this discomfort zone usually starts between 20 and 40 centimeters away and continues right up to the face, researchers report August 28 in the Journal of Neuroscience. Threatening objects that enter this forbidden space are likely to trigger a strong defensive reaction. Scientists knew that this safety margin exists, but its boundaries hadn’t been measured.
Chiara Sambo and Giandomenico Iannetti of University College London zapped 15 people on the wrist, a process known to make people blink defensively. Simultaneously, the researchers moved the same hand closer and closer to the subjects’ faces and measured the amount of blinking that ensued. On average, people displayed a boundary between about 20 and 40 centimeters before rapid blinking betrayed a defensive reaction, the experiment showed. A jolt 40 centimeters away was OK, but a jolt 20 centimeters away was definitely not.
What’s more, personality changed the size of the zone: People who reported more anxiety needed a wider berth.