Concepts are vital to human survival, but we must also be careful with them because concepts open the door to essentialism. They encourage us to see things that aren't present. Stuart Firestein opens his book, Ignorance, with an old proverb, It is very difficult to find a black cat in a dark room, especially when there is no cat. This statement beautifully sums up the search for essences. History has many examples of scientists who searched fruitlessly for an essence because they used the wrong concept to guide their hypotheses. Firestein gives the example of luminiferous ether, a mysterious substance that was thought to fill the universe so that light would have a medium to move through. The ether was a black cat, writes Firestein, and physicists had been theorizing in a dark room, and then experimenting in it, looking for evidence of a cat that did not exist.

While social media attention is potentially an instrument to achieve ends like elite celebrity, some content creators desire ordinary fame as a social end in itself. Not unlike reality television stars, social media celebrities are often criticized for not having skills and talents associated with traditional, elite celebrity, such as acting or singing ability. This criticism highlights the fact that digital content creators face real barriers to crossing over to the sphere of elite celebrity. However, the criticism also misses the point that the phenomenon of ordinary celebrity reconstructs the meaning of fame. The elite celebrity is symbolized by the metaphor of the star, characterized by mystery and hierarchical distance and associated with naturalized qualities of talent and class. The ordinary celebrity attracts attention through regular and frequent interactions with other ordinary people. Achieving ordinary fame as a social media celebrity is like doing well at a game, because in this sphere, fame is nothing more nor less than relatively high scores on attention scales, the metrics of subscribers, followers, Likes, or clicks built into social media applications.

Why do we have the illusion that cramming for an exam is the best learning strategy? Because we are unable to differentiate between the various sections of our memory. Immediately after reading our textbook or our class notes, information is fully present in our mind. It sits in our conscious working memory, in an active form. We feel as if we know it, because it is present in our short-term storage space ... but this short-term section has nothing to do with the long-term memory that we will need in order to recall the same information a few days later. After a few seconds or minutes, working memory already starts disappearing, and after a few days, the effect becomes enormous: unless you retest your knowledge, memory vanishes. To get information into long-term memory, it is essential to study the material, then test yourself, rather than spend all your time studying.

The discovery of mirror neurons has profoundly changed the way we think of a fundamental human capacity, learning by observation. As children we learn a lot by observing what our parents and friends do. Newborns, in the first week of life, have an inborn tendency to stick out their tongue if their parents stick out theirs. Such imitation is not perfect. You may not see the tongue stick out each time you stick yours out at your newborn, but if you do it many times, the tongue will come out more often than if you do something different. Babies babble and later start to imitate the sounds their parents produce. Later still, they play with vacuum cleaners and hammers in imitation of their parents. Our modern cultures, in which we write, speak, read, build spaceships and go to school, can work only because we are not restricted to the behavior we are born with or learn by trial and error. We can learn a lot by simply watching others.

Have you ever been surprised to hear a recording of your own voice? You might have thought, Is that really what my voice sounds like? Maybe your accent is more pronounced in the recording than you realized, or your voice is higher than it seems to your own ears. This is of course quite a common experience. The explanation is actually fairly simple. There are two pathways through which we perceive our own voice when we speak. One is the route through which we perceive most external sounds, like waves that travel from the air through the outer, middle and inner ear. But because our vocal cords vibrate when we speak, there is a second internal path. Vibrations are conducted through our bones and stimulate our inner ears directly. Lower frequencies are emphasized along this pathway. That makes your voice sound deeper and richer to yourself than it may sound to other people.

Biologists distinguish two kinds of similarity. Analogous traits are ones that have a common function but arose on different branches of the evolutionary tree and are in an important sense not the same organ. The wings of birds and the wings of bees are both used for flight and are similar in some ways because anything used for flight has to be built in those ways, but they arose independently in evolution and have nothing in common beyond their use in flight. Homologous traits, in contrast, may or may not have a common function, but they descended from a common ancestor and hence have some common structure that indicates their being the same organ. The wing of a bat and the front leg of a horse have very different functions, but they are all modifications of the forelimb of the ancestor of all mammals. As a result, they share nonfunctional traits like the number of bones and the ways they are connected. To distinguish analogy from homology, biologists usually look at the overall architecture of the organs and focus on their most useless properties.

Seawater contains an abundance of dissolved oxygen that all marine animals breathe to stay alive. It has long been established in physics that cold water holds more dissolved oxygen than warm water does ― this is one reason that cold polar seas are full of life while tropical oceans are blue, clear, and relatively poorly populated with living creatures. Thus, as global warming raises the temperature of marine waters, it is self-evident that the amount of dissolved oxygen will decrease. This is a worrisome and potentially disastrous consequence if allowed to continue to an ecosystem-threatening level. Now scientists have analyzed data indicating that the amount of dissolved oxygen in the oceans has been declining for more than a half century. The data show that the ocean oxygen level has been falling more rapidly than the corresponding rise in water temperature. Falling oxygen levels in water have the potential to impact the habitat of marine organisms worldwide and in recent years this has led to more frequent anoxic events that killed or displaced populations of fish, crabs, and many other organisms.

Capuchins ― New World Monkeys that live in large social groups ― will, in captivity, trade with people all day long, especially if food is involved. I give you this rock and you give me a treat to eat. If you put two monkeys in cages next to each other, and offer them both slices of cucumber for the rocks they already have, they will happily eat the cucumbers. If, however, you give one monkey grapes instead ― grapes being universally preferred to cucumbers ― the monkey that is still receiving cucumbers will begin to throw them back at the experimenter. Even though she is still getting paid the same amount for her effort of sourcing rocks, and so her particular situation has not changed, the comparison to another makes the situation unfair. Furthermore, she is now willing to abandon all gains ― the cucumbers themselves ― to communicate her displeasure to the experimenter. -> According to the passage, if the Capuchin monkey realizes the inequality in rewards compared to another monkey, she will reject her rewards to express her feelings about the treatment, despite getting exactly the same rewards as before.

When we see something, we naturally and automatically break it up into shapes, colors, and concepts that we have learned through education. We recode what we see through the lens of everything we know. We reconstruct memories rather than retrieving the video from memory. This is a useful trait. It's a more efficient way to store information - a bit like an optimal image compression algorithm such as JPG, rather than storing a raw bitmap image file. People who lack this ability and remember everything in perfect detail struggle to generalize, learn, and make connections between what they have learned. But representing the world as abstract ideas and features comes at a cost of seeing the world as it is. Instead, we see the world through our assumptions, motivations, and past experiences. The discovery that our memories are reconstructed through abstract representations rather than played back like a movie completely undermined the legal primacy of eyewitness testimony. Seeing is not believing.

In his Cornell laboratory, David Dunning conducted experimental tests of eyewitness testimony and found evidence that a careful deliberation of facial features and a detailed discussion of selection procedures can actually be a sign of an inaccurate identification. It's when people find themselves unable to explain why they recognize the person, saying things like his face just popped out at me, that they tend to be accurate more often. Sometimes our first, immediate, automatic reaction to a situation is the truest interpretation of what our mind is telling us. That very first impression can also be more accurate about the world than the deliberative, reasoned self-narrative can be. In his book Blink, Malcolm Gladwell describes a variety of studies in psychology and behavioral economics that demonstrate the superior performance of relatively unconscious first guesses compared to logical step-by-step justifications for a decision.