1 00:00:02,040 --> 00:00:07,360 Speaker 1: Welcome to brain Stuff from how Stuff Works. Hey, brain Stuff, 2 00:00:07,400 --> 00:00:11,479 Speaker 1: Lauren Vogel bomb here. Think of a pair of synchronized divers, 3 00:00:11,760 --> 00:00:14,520 Speaker 1: or the wings on a butterfly, or the vaulted ceiling 4 00:00:14,560 --> 00:00:17,320 Speaker 1: of a cathedral. These are some of the things that 5 00:00:17,360 --> 00:00:21,720 Speaker 1: most people find visually very pleasing. But why. The answer 6 00:00:21,760 --> 00:00:25,120 Speaker 1: has to do with symmetry. Most objects in the real 7 00:00:25,200 --> 00:00:29,040 Speaker 1: world are symmetrical. This is particularly true of nature, the 8 00:00:29,280 --> 00:00:32,560 Speaker 1: radial symmetry of a starfish or flower petals, the symmetrical 9 00:00:32,600 --> 00:00:36,760 Speaker 1: efficiency of a hexagonal honeycomb, or the uniquely symmetrical crystal 10 00:00:36,760 --> 00:00:40,360 Speaker 1: patterns of a snowflake. In fact, asymmetry is often a 11 00:00:40,400 --> 00:00:43,440 Speaker 1: sign of illness or danger in the natural world, and 12 00:00:43,600 --> 00:00:47,040 Speaker 1: of course, human beings are symmetrical, at least mostly and 13 00:00:47,440 --> 00:00:49,760 Speaker 1: on the outside. You know, some internal organs like the 14 00:00:49,800 --> 00:00:53,080 Speaker 1: heart and liver are off center. Decades of research into 15 00:00:53,080 --> 00:00:55,800 Speaker 1: sexual attraction have proven that both men and women find 16 00:00:55,840 --> 00:01:00,320 Speaker 1: symmetrical faces sexier than asymmetrical ones. The leading explanation is 17 00:01:00,360 --> 00:01:02,840 Speaker 1: the physical symmetry is an outward sign of good health, 18 00:01:03,160 --> 00:01:06,320 Speaker 1: although large scale studies have shown no significant health differences 19 00:01:06,319 --> 00:01:10,600 Speaker 1: in people with symmetrical or asymmetrical faces. Since severe physical 20 00:01:10,680 --> 00:01:14,080 Speaker 1: asymmetries are strong indicators of genetic disorders. Our brains might 21 00:01:14,080 --> 00:01:17,560 Speaker 1: just be overreacting. The simple explanation for our attraction to 22 00:01:17,560 --> 00:01:21,560 Speaker 1: symmetry is that it's familiar symmetrical objects and images played 23 00:01:21,560 --> 00:01:24,480 Speaker 1: by the rules that our brains are programmed to recognize easily. 24 00:01:25,480 --> 00:01:28,120 Speaker 1: Physicist Alan Lightman wrote about this in his book The 25 00:01:28,160 --> 00:01:31,479 Speaker 1: Accidental Universe The World You Thought You Knew. He wrote, 26 00:01:31,880 --> 00:01:34,880 Speaker 1: I would claim that symmetry represents order, and we crave 27 00:01:35,000 --> 00:01:37,760 Speaker 1: order in this strange universe. We find ourselves in the 28 00:01:37,760 --> 00:01:40,480 Speaker 1: search for symmetry, and the emotional pleasure we derive when 29 00:01:40,520 --> 00:01:42,679 Speaker 1: we find it must help us make sense of the 30 00:01:42,680 --> 00:01:45,319 Speaker 1: world around us, just as we find satisfaction in the 31 00:01:45,360 --> 00:01:48,280 Speaker 1: repetition of the seasons and in the reliability of friendships. 32 00:01:48,600 --> 00:01:53,280 Speaker 1: Symmetry is also economy. Symmetry is simplicity, Symmetry is elegance. 33 00:01:54,160 --> 00:01:57,640 Speaker 1: At the esoteric end of the explanation spectrum, Lightment is 34 00:01:57,680 --> 00:02:00,360 Speaker 1: saying that the satisfaction we feel at seeing a creatively 35 00:02:00,360 --> 00:02:03,240 Speaker 1: symmetrical work of art or a perfectly stacked display of 36 00:02:03,280 --> 00:02:06,080 Speaker 1: soup cans at the grocery store is that the stuff 37 00:02:06,200 --> 00:02:09,280 Speaker 1: of our brains is inseparable from the stuff of nature. 38 00:02:09,600 --> 00:02:12,359 Speaker 1: The neurons and synapses in our brains and the processes 39 00:02:12,400 --> 00:02:15,680 Speaker 1: by which they communicate, connect, and conjure thoughts evolved in 40 00:02:15,760 --> 00:02:19,760 Speaker 1: parallel to snowflakes and starfish. If nature is symmetrical, then 41 00:02:19,800 --> 00:02:23,160 Speaker 1: so are our minds. On the more basic end, the 42 00:02:23,240 --> 00:02:25,480 Speaker 1: pleasure we get from symmetry could simply be due to 43 00:02:25,480 --> 00:02:28,320 Speaker 1: our minds need to find patterns and attempt to make 44 00:02:28,360 --> 00:02:31,600 Speaker 1: sense of things, especially quickly and with a limited data set. 45 00:02:32,160 --> 00:02:35,519 Speaker 1: Considered the Stalt psychology, named after an influential school of 46 00:02:35,560 --> 00:02:38,280 Speaker 1: visual perception born in Germany in the nineteen twenties. The 47 00:02:38,360 --> 00:02:42,320 Speaker 1: famous and famously mistranslated gives Stalt motto is the whole 48 00:02:42,600 --> 00:02:45,280 Speaker 1: is other than the sum of its parts, not the 49 00:02:45,320 --> 00:02:47,799 Speaker 1: whole is greater than the sum of its parts. Our 50 00:02:47,800 --> 00:02:50,200 Speaker 1: brain is more than a calculator adding up the details 51 00:02:50,240 --> 00:02:53,160 Speaker 1: of a scene. It's primed to recognize signs of order 52 00:02:53,200 --> 00:02:56,480 Speaker 1: in the accidental chaos and to follow certain rules or 53 00:02:56,480 --> 00:02:59,480 Speaker 1: shortcuts to make sense of the world. Symmetry is one 54 00:02:59,520 --> 00:03:02,160 Speaker 1: of those short cuts. We spoke with Mary Peterson, a 55 00:03:02,160 --> 00:03:05,760 Speaker 1: psychology professor and director of the Visual Perception Laboratory at 56 00:03:05,760 --> 00:03:09,480 Speaker 1: the University of Arizona. As she says, the brain doesn't 57 00:03:09,480 --> 00:03:12,920 Speaker 1: like things that are accidental. We either learn or born 58 00:03:13,000 --> 00:03:15,840 Speaker 1: with certain priors or shortcuts that help our brains quickly 59 00:03:15,880 --> 00:03:18,720 Speaker 1: determined that we're looking at one particular object or another. 60 00:03:20,040 --> 00:03:23,840 Speaker 1: We also spoke with Johann vachu Launch, an experimental psychologist 61 00:03:23,880 --> 00:03:27,000 Speaker 1: from Belgium who specializes in visual perception and how our 62 00:03:27,040 --> 00:03:31,400 Speaker 1: brains organized the constant incoming flow of information. He agrees 63 00:03:31,440 --> 00:03:33,720 Speaker 1: as symmetry is not just a design principle of the 64 00:03:33,760 --> 00:03:37,440 Speaker 1: outside world. He said, you can also see symmetry as 65 00:03:37,480 --> 00:03:40,400 Speaker 1: one of these major principles driving the self organization of 66 00:03:40,400 --> 00:03:43,760 Speaker 1: the brain. All these tendencies toward good organization and simple 67 00:03:43,880 --> 00:03:47,080 Speaker 1: organization are also principles of symmetry in the dynamics of 68 00:03:47,120 --> 00:03:50,400 Speaker 1: the brain itself. But on the other hand, too much 69 00:03:50,440 --> 00:03:53,920 Speaker 1: symmetry can be a tad boring. While perfectly symmetrical designs 70 00:03:53,920 --> 00:03:57,240 Speaker 1: are more pleasing to the brain, they're not necessarily more beautiful. 71 00:03:57,800 --> 00:04:01,119 Speaker 1: Both art novices and experts prefer art that strikes, says 72 00:04:01,200 --> 00:04:05,360 Speaker 1: vocumons an optimal level of stimulation, not too complex, not 73 00:04:05,440 --> 00:04:09,080 Speaker 1: too simple, not too chaotic, and not too orderly. Indeed, 74 00:04:09,120 --> 00:04:12,680 Speaker 1: the Japanese have an esthetic principle called quinsey, which is 75 00:04:12,720 --> 00:04:21,480 Speaker 1: all about creating balance in a composition using asymmetry or irregularity. 76 00:04:23,400 --> 00:04:25,840 Speaker 1: Today's episode was written by Dave Rouse and produced by 77 00:04:25,839 --> 00:04:28,400 Speaker 1: Tristan McNeil. For more on this and tons of other 78 00:04:28,400 --> 00:04:43,440 Speaker 1: brainy topics, visit our home planet, how stuff works dot com.