Cognition refers to the mental processes by which people acquire knowledge, solve problems, and plan for the future.

Simply put, cognition is the process of thinking. Cognitive functions in the brain include attention, perception, thinking, judging, decision making, problem solving, memory, and linguistic ability. Cognition depends on the ability to imagine or represent objects and events that are not physically present at a given moment.

One of the most basic cognitive functions is the ability to conceptualize, or group individual items together as instances of a single concept or category, such as “apple” or “chair.” Concepts are abstract ideas that provide the basic framework for thought, allowing people to relate most objects and events they encounter to categories that already exist in their minds from knowledge or past experiences.

People learn concepts by gradually building on their first ideas and adding to or altering those ideas. When a person uses cognitive reasoning, he or she forms and tests theories about ideas and categories. Most thinking combines concepts in different forms. Examples of different forms concepts take include propositions (proposals or possibilities), mental models (visualizing the physical form an idea might take), schemas (diagrams or maps), scripts (scenarios), and images (physical models of the item). Reasoning is the process by which people formulate arguments and arrive at conclusions, and problem solving involves devising a useful description of a problem in one's mind and planning, executing, and evaluating a solution.

Memory—another cognitive function—is crucial to learning, communication, and even to one's sense of identity (as evidenced by the effects of amnesia). Short-term memory provides the basis for each individual's working model of the world and makes possible most other mental functions; long-term memory stores information for longer periods of time. A newer concept called working memory refers to how the brain controls the information it receives so that people can store and recall the information as needed. The three basic processes common to both short-and longterm memory are encoding, which deposits information in the memory; storage; and retrieval. Each of these types of memory are affected differently, and research continues to study how each type is encoded, stored, and retrieved in the brain. Scientists know that with age, short-term memory, such as the name of a person recently met, typically does not work as well as long-term memory.

The cognitive function that most distinctively sets humans apart from other animals is the ability to communicate through language, which involves expressing ideas as sentences and understanding such expressions when we hear or read them. Language also enables the mind to communicate with itself. The interaction between language and thought has been a topic of much speculation. Of historical interest is the work of Benjamin Whorf (1897–1941), the proponent of the idea that the language people use determines the way in which they view the world. As of 2015, there are differing views on whether the Whorfian hypothesis is valid, and only some research to support it. Still, language and culture likely are linked. More importantly, language and cognition are related in an individual's thinking, not just in how the person communicates those thoughts.

Language acquisition is another topic of debate, with some—including psycholinguist Noam Chomsky (1928–)—arguing that all humans have innate language abilities, though others stress the role of conditioning and social learning theories that emphasize imitation, repetition, or typical learning methods.


In his book-length case study The Man with a Shattered World, Russian psychologist A.R. Luria tells the story of a soldier named Zasetsky, who suffered a head injury during the battle of Smolensk in 1943. Zasetsky (Z) was 23 years old when shrapnel destroyed the parietal lobe of the left hemisphere of his brain. He recovered from a prolonged coma but was left with a complex range of cognitive problems and symptoms both acute and chronic.

As Luria describes, “The bullet fragment that entered his brain had so devastated his world that he no longer had any sense of space, could not judge relationships between things, and perceived the world as broken into thousands of separate parts.”

The book consists largely of the patient's own journal, painstakingly written over the course of over 25 years, despite significant language impairments, along with comments and analysis by Luria. It was first published in Russian in 1971.

Luria sought to “revive the tradition of romantic science” and provide a full, human picture of a neurological condition rather than just a collection of cold data.

Z's perception of the world was fragmented. He couldn't visualize general things like a cat or a dog, nor specific faces (though he did recognize his mother and sisters despite not being able to picture them before seeing them), nor could he visualize or recognize geographic areas. Even after living in a small town for years he could not recognize or remember any of the streets or the architectural layout of the town. He also had spatial problems and described his difficulty judging the position of a chair he was about to sit in, often finding it was closer to him or further to the right than he thought.

The brain injury affected Z's body image and body awareness. He had complete blindness on his right side, and beyond that, an unawareness of the right side of his body (this is referred to as hemineglect). He also could not remember where his body parts were located or what they were called.

Z had trouble with writing and understanding even simple arithmetic. Writing was impossible until it was suggested he try writing ‘automatically,’ without picking up his pencil. This allowed him to complete his 3,000page journal, which was the basis for the book. He had significant difficulties reading—a condition known as alexia—and described words as looking foreign to him. He made improvement in his reading abilities, often having to read words letter by letter. Z recalls, “After a few months I could remember the whole alphabet. However, I still couldn't identify any of the letters immediately. When the teacher asked me to point to the letter k, I'd have to think for awhile and recite the alphabet until I got to k! For some reason, I still knew how to recite the alphabet and could run through it without a hitch.” The fact that Z could still recite the alphabet as he had as a child suggested to Luria that this was an oral-motor skill requiring a part of the brain that had not been damaged.

Z's case provided Luria with important insights about the organization of cognition and different functions in the brain, and contributed to his theories about higher cortical function, as outlined in his book Higher Cortical Functions in Man. Luria inferred that the parts of Z's cortex that were damaged were the areas that control “analysis, synthesis and organization of complex associations into a coherent framework.” Thus, Z's perceptions of the world were fractioned, shattered.

The book brought attention to the field of neuropsychology and provides insight into the effects of brain injury and the nature of human cognition. It is also an inspiring story of will and an insight into the human condition. It illustrates in human terms, rather than in cold clinical data, the experience of a man adapting to and living with brain damage.

The development of the modern computer has influenced current ways of thinking about cognition through computer simulation of cognitive processes for research purposes and through the creation of information-processing models. These models portray cognition as a system that receives information, represents it with symbols, and then manipulates the representations in various ways. The senses transmit information from outside stimuli to the brain, which applies perceptual processes to interpret it and then decides how to respond to it. The information may simply be stored in the memory or it may be acted on. Acting on it usually affects a person's environment in some way, providing more feedback for the system to process. Major contributions in the area of information processing include D.E. Broadbent's information theory of attention, learning, and memory; and Miller, Galanter, and Pribram's analysis of planning and problem solving. IBM Research is an example of cognitive computing. The company famously developed a computer with artificial intelligence named “Watson” that defeated two former champions of the television game show Jeopardy.


Artificial intelligence
—Programming intelligence into computer software or machines.
Cognitive psychology
—The scientific study of the brain and how itfunctions to contributeto memory, learning, reasoning, emotions, and mental disorders.
Linguistic ability
—Language skills, and the ability to acquire them.

See also Artificial intelligence ; Cognitive development .



Anderson, John R. Cognitive Psychology and Its Implica tions. 8th ed. New York: Worth Publishers, 2014.

Ashcraft, Mark H. Cognition. New York: Pearson Publishers, 2013.


Bickerton, Derek. “Saving Endangered Languages.” Psychology Today. (accessed August 3, 2015).

“Memory 101: Learn the Different Types of Memory and How to Keep it Strong. (accessed August 3, 2015).


American Academy of Neurology and American Brain Foundation, 201 Chicago Avenue, Minneapolis, MN, 55415, (612) 928-6000, (800) 879-1960, .