 Cognitive science is the interdisciplinary scientific study of the mind in its processes. It examines the nature, tasks and the functions of cognition. Cognitive scientists study intelligence and behavior with a focus on how nervous systems represent, process and transform information. The human brain weighs approximately 3 pounds or 1.4 kilograms, although it only makes up about 2% of the total body weight of an adult human being. Brain tissue consumes a large amount of energy in proportion to its volume. Most of the brain's energy consumption goes into sustaining the electrical charge of the neurons. Cognitive vertebrae species devote about 2 to 8% of basic metabolism to the brain. In primates, however, the percentage is much higher. In humans, it can rise to as much as 20 to 25%. The mind is composed of approximately 100 billion neurons, connected together into a neural network. Neural networks are made of neurons and connections between them called axons, which have synapses where the different neurons meet. Neurons generate electrical signals that travel along their axons. When a pulse of electricity reaches a junction called a synapse, it causes a neurotransmitter chemical to be released, which binds to receptors on other cells and thereby alters their electrical activity. The property that makes neurons unique is their ability to send signals to specific target cells over long distances. They send these signals by means of axons, which is a thin protoplasmic fiber which extends from the cell body and projects, usually with numerous branches to other areas sometimes nearby, sometimes in distant parts of the brain or body. Each of the 100 billion neurons has on average 7,000 synapse connections to other neurons. In its functioning, a neuron is a form of switch, that is to say a cell that is either on or off. Any given neuron has a number of inputs from other neurons. If those inputs are above a given threshold, then it is activated and fires. If a neuron is activated, it then sends out signals to other neurons that it's connected to. Its output then becomes the input to other neurons. Where the output to one neuron meets the input to another, there is a synapse. These synapses change in their chemical composition as one learns in order to create stronger connections. In such a way, the cognitive system can develop and changes over time to form new patterns of neural networks. The brain is physically built as a neural network and cognition happens in patterns. Every pattern corresponds to an idea or memory. If two neurons are turned on when a pattern is stimulated, then the synaptic connection between them becomes stronger. If they are not on at the same time, then the connection between them becomes weaker. Over time, if the same pattern keeps getting excited, then the connections get stronger between the neurons that are activated. After a time, a pattern can form that remains there even when not excited. By repeating something over and over, a pathway is activated to form a pattern. This pattern is a memory or concept that one can then use for cognition. The brain is hardwired to discern patterns. Humans have a well-documented tendency for pattern recognition. It is both a great cognitive strength, but also can be a weakness because we may see patterns that do not actually exist. Humans are generally very good at pattern recognition, so good in fact that we may often see patterns that are not actually there. Brain processing is based largely on processes of pattern cognition, which matches the underlying biological structure of the brain as a massive parallel processor with many connecting neural networks. One of the advantages of this is our innate strength at making connections between different ideas, visual patterns, words, events, objects, etc. Pattern recognition is filtered through a particular module of the brain that undertakes what is called reality testing. We see many apparent patterns in the world around us, and then we run these patterns through a reality testing algorithm to decide whether it agrees with our internal model of reality. Once one has formed a pattern, exciting one part of the network may then stimulate the full pattern. For example, a slight aroma of fresh bread in the kitchen can trigger a whole network of connections associated with some memory in a cafe a few years earlier. We identify and learn about things in relation to pre-existing patterns within our conscience. This means one can only learn something new or understand something if one can associate it with something one already knows about. If we want to communicate with someone, we have to accommodate the fact that what we can say has to be associated with something they already know for it to be effectively interpreted. We can learn something new very quickly if we can associate it with other things and fit it into a larger pattern. We can readily identify a new type of dog as an instance of our pre-existing pattern of a generic dog. Likewise, we think and learn by association, and thus when explaining something new we typically give an example as this helps to create the associations. The mind is a hierarchically layered network structure with this hierarchy being based on abstraction, that is to say more basic patterns on the lower levels are used as the building blocks for higher, more abstract patterns. Abstraction in its main sense is a conceptual process by which general rules and concepts are derived from the usage and classification of more specific examples, that is to say more concrete forms. In the development of the brain more basic patterns are formed and then grouped to create higher level patterns. The patterns to one layer become the input to another layer. The lowest level of abstraction is connected directly to the senses, providing the data or facts that are inputted. We then build up higher level patterns through a process of abstraction and synthesis, abstracting away the specific instances in synthesizing them into generic forms. In an evolutionary sense, our biological brains are a lizard brain inside of a mammal brain inside of a primate brain inside of a human brain, which is the most recently evolved part of our brains, the neocortex. It is possible for our brain to hierarchically control lower level functions from higher levels all the way down to the most basic primitive levels down to our brain stem. We can directly control very basic functions within our brain stem, such as the regulation of our breathing and maintenance of balance from our most abstract and advanced levels of consciousness. Much of our cognition takes place subconsciously in the more primitive parts of our brain, where the emotions take place. Emotions make quick decisions for us that are mainly adaptive, including such states as fear, lust, hunger, happiness and sadness. Emotions provide us with a very direct behavioral motivation. It is much easier for us to feel repelled by something like a piece of rotten food rather than for us to have to reason through it to generate a response. Without these emotions, we would have to reason everything through, but with them, we simply experience the emotion, such as fear when presented with a dangerous predator, and then we can react quickly based upon that emotion, without need for advanced cognition. Our decisions seem to be conscious, but they are often made subconsciously by an evolutionary neurobiological calculus that we are not aware of. Emotions are subconscious and involuntary. We do not choose to feel fear, we just feel fear and then invent a reason to explain why we feel it, with varying degrees of correspondence between the emotional cause and the rationalization. In addition to decision making, intuition is a form of subconscious processing. For example, emotional processing, social cues and the monitoring of our internal state are largely subconscious processes. An interesting piece of research in this regard is a 2008 paper published in Nature magazine using fMRI scanning to look at brain activity while subjects were undergoing a decision making test to reveal the degree of unconscious thought processing involved. What these tests showed was that the decision was often present in the subjects brain 10 seconds prior to them actually being conscious of it. Approximately 60% of the time, the researchers were able to tell what decisions the individuals were going to make before they were conscious of it. This piece of research illustrates how subconscious activity may often come to decisions before we're even consciously aware of them.