Free Idiot Brain by Dean Burnett Page A

section. The brain does tend to group our senses together more often than seems practical. But on the other hand, it does suggest people can “feel the rhythm” in a more literal manner than is generally assumed.
    Jesus has returned . . . as a piece of toast?
    (What you didn’t know about the visual system)
    What do toast, tacos, pizza, ice-cream, jars of spread, bananas, pretzels, potato chips and nachos have in common? The image of Jesus has been found in all of them (seriously, look it up). It’s not always food though; Jesus often pops up in varnished wooden items. And it’s not always Jesus; sometimes it’s the Virgin Mary. Or Elvis Presley.
    What’s actually happening is that there are uncountable billions of objects in the world that have random patterns of color or patches that are either light or dark, and by sheer chance these patterns sometimes resemble a well-known image or face. And if the face is that of a celebrated figure with metaphysical properties (Elvis falls into this category for many)then the image will have more resonance and get a lot of attention.
    The weird part (scientifically speaking) is that even those who are aware that it’s just a grilled snack and not the bread-based rebirth of the Messiah can still see it. Everyone can still recognize what is said to be there, even if they dispute the origins of it.
    The human brain prioritizes vision over all other senses, and the visual system boasts an impressive array of oddities. As with the other senses, the idea that the eyes capture everything about our outside world and relay this information intact to the brain like two worryingly squishy video cameras is a far cry from how things really work. ‡
    Many neuroscientists argue that the retina is part of the brain, as it develops from the same tissue and is directly linked to it. The eyes take in light through the pupils and lenses at the front, which lands on the retina at the back. The retina is a complex layer of photoreceptors, specialized neurons for detecting light, some of which can be activated by as little as half-a-dozen photons (the individual “bits” of light). This is very impressive sensitivity, like a bank security system being triggered because someone had a thought about robbing the place. The photoreceptors that demonstrate such sensitivity are used primarily for seeing contrasts, light and dark, and are known as rods. These work in low-light conditions, such as at night. Bright daylightactually oversaturates them, rendering them useless; it’s like trying to pour a gallon of water into an egg cup. The other (daylight-friendly) photoreceptors detect photons of certain wavelengths, which is how we perceive color. These are known as cones, and they give us a far more detailed view of the environment, but they require a lot more light to be activated, which is why we don’t see colors at low light levels.
    Photoreceptors aren’t spread uniformly across the retina. Some areas have different concentrations from others. We have one area in the center of the retina that recognizes fine detail, while much of the periphery gives only blurry outlines. This is due to the concentrations and connections of the photoreceptor types in these areas. Each photoreceptor is connected to other cells (a bipolar cell and a ganglion cell usually), which transmit the information from the photoreceptors to the brain. Each photoreceptor is part of a receptive field (which is made up of all the receptors connected to the same transmission cells) that covers a specific part of the retina. Think of it like a cell-phone tower, which receives all the different information relayed from the phones within its coverage range and processes them. The bipolar and ganglion cells are the tower, the receptors are the phones; thus there is a specific receptive field. If light hits this field it will activate a specific bipolar or ganglion cell via the photoreceptors