The 19th century started the argument of localism vs. holism in cognitive neuropsychology. People were starting to question holism and explore the idea of localism. Localism means that the brain has individual areas that are responsible for certain actions in the body. The study of Phrenology started these localization theories. Phrenology is looking at the human skull and finding strange bumps to be measured. Any strange bumps or shapes in the skull were then paired with intelligence or self traits in a person. These traits could include language, logic, and even love. If a part of the skull was pushed out it would mean that trait was better. This started localization theories
The next big thing in cognitive neuroscience has to do with ablation studies. This is when parts of the brain were removed so function could be measured without this brain area. For example, a neuropsychologist can remove the cerebellum. After it is removed, the animal's balance was not good. This links the cerebellum to balance. As for brain damage, the most famous case is with Phineas Gage. This patient was working on the railroad when a piece of metal went through the front of his head. He did not die from this brain injury. However, his normal personality changed. This brought the idea that the frontal cortex, the part of the brain that was stabbed, controlled how a person acted. Another study found the localization of language in the brain. Two separate scientists studied patients with language problems. They found that their patients all had lesions or damage in two certain areas of their brain. One area known as Broca's area controlled talking. The other area Wernicke's area was found to control understanding of language.
This way of looking at problems in the brain lead to studies of epileptic patients. An epileptic patient is a person that frequently suffers from seizures. These seizures were studied to learn more about how the brain sends electrical signals. These electrical signals were then measured. It was found that each neuron can send a signal at certain speeds. These neurons were then dyed with a stain in order to be seen. At first it was thought that all nerves were connected like a web called a nerve net. However, with more complex stain it was found that each nerve is separate and can fire on their own.
In the early part of the 20th century, there was a long time that cognitive neuropsychology was not studied. This was partly because of the influence of John B. Watson, who was a behaviorist in psychology. He argued that cognition could not be studied scientifically because it could not be observed. So for the first half of the 20th century, psychology as a field was dominated by behaviorism, which was mainly stimuli and a person’s response to it. John B. Watson was only one psychologist to criticize cognitive psychology. Pierre Marie in 1906 criticized Broca, who was one of the first to create the field of Cognitive Neuropsychology. Henry Head in 1926 also attacked the whole field of cognitive neuropsychology. Due to these criticisms, and the influence of behaviorism, cognitive neuropsychology was dormant for many years.
Another reason why cognitive neuropsychology disappeared in the early twentieth century was because the science was not yet advanced enough. Many cognitive psychologists were also neurologists. These two fields of study were not separate yet, as they are today. These neurologists wanted to study modules in the brain, and localize them with parts of the brain, but technology did not allow this yet. The methods used today were not yet created. They could only study where a person’s brain lesion was by doing an autopsy after the person was already dead. This was a lot of the reason this field was criticized against, and why many people believed cognition could not be studied scientifically.
In the middle of the twentieth century there was a transition called the 'Cognitive Revolution' in psychology. This is when psychologists began to agree that there were scientific ways to study cognition. These new beliefs about cognitive psychology were brought on by John C. Marshall's and Nora Newcombe’s study of reading, and Shallice and Warrington’s study of memory in the early 1970s. In the mid 1980s the first undergraduate book was published by Ellis & Young named "Human Cognitive Neuropsychology". There was also an emergence of new technology that made it easier to study the brain and the mind. The 1970s and 1980s was the time period that cognitive neuropsychology became visible, and many psychologists started studying it after.
An important feature of the later half of the twentieth century was the clear separation of cognitive neuropsychology and cognitive neuroscience. Cognitive neuropsychologists study the human mind after brain damage has occurred, and focus more on cognition. Cognitive neuroscientists study the human brain and neural systems after brain damage has occurred, and focus more attention on the neurons. While the cognitive neuroscientists are concerned with how the brain works, and what parts of the brain is responsible for what functions, cognitive neuropsychologists want to study people with brain damage to try and see how the human mind works. With this information, they can formulate theories about the human mind, and also make better therapies for people with brain damage.
An important feature that was developed in the twentieth century is the way that research is conducted. Since every single person’s brain damage is different, cognitive neuropsychologists study only single cases instead of groups of people, or syndromes. Psychologists study the mind by looking at people who lost some sort of function after brain damage occurred. For example, if a person could recognize both faces and objects before brain damage occurred, but then after brain damage in a certain part of the brain they could only recognize faces and not objects, then psychologists can make inferences about the functions in certain modules of the brain.
The late 20th century was also when they began using computational models of cognition. The psychologists would make theories and install them into a computer, then virtually damage the fake brain where the patient had damage. By doing this, they can get a better look at how the mind works. This is one way that technology has helped in studying the human mind. This, along with the invention of the devices to scan the brain, has made a big difference in cognitive neuropsychology.
Cognitive neuropsychologists use the method of double dissociation when studying the modules of the mind. This is when they use many patients who have had brain damage and try to figure out which parts of the brain are responsible for different cognition. This concept of modularity was developed by Jerry Fodor in his 1983 book The Modularity of the Mind. Psychologists disagree as to how much and which parts of the mind is constructed modules.
In this century, cognitive neuropsychologists use many methods to study the mind. They use machines that scan the brain to see where the damage is, and then study cognitive abilities of these patients. They still use double dissociation for studying the patients, case studies, computational models, and many other features that were invented in the late twentieth century. With new technology, there is likely to be a lot of improvement in this field.
Cognitive neuropsychology uses of investigations of people with problems of cognition to learn more about normal cognitive processes. This is possible through the many technological advances such as:
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