The Science of Productivity: Human Intelligence

While contemporary and popular science is shifting its focus toward artificial intelligence, I think it is nice to go back to the aspects that make human intelligence human (for perspective purposes). These aspects orchestrate cognitive (or “mental”) processes that allow us to observe, reason, question, learn, and recall facts and experiences. Have you ever questioned what makes your thoughts exist? Or even how is it possible for you to formulate questions? I love the topic and in this post I will provide you with a taste of it! I hope we can both get to learn about what makes us human; it looks like the Greek aphorism: “Know thyself” remains valid, huh?

What is human intelligence?

Human intelligence is broadly defined as a “general mental ability for reasoning, problem solving and learning”. The human mind is so powerful. Think of this: you can think and reason about virtually any issue. For instance, you are asked to imagine an empty room, or to imagine your favorite color, favorite food, or to recall your favorite song, or you are asked a “What if…?” question. The fact that you were brainstorming while reading the last sentence is a proof of the sort of complex gear machinery working 24/7 in our brains.

Intelligence is a plastic (that means changing, flexible, malleable) capacity of our brains. It allows us to “learn-and-adapt-to-survive”. Does it ring a bell? Yes, it is Darwin’s theory of evolution.

Let’s break it down: intelligence is an integrative ability. This means that it incorporates certain information (data) from other more simple cognitive processes. In the field of psychology, the Cattell-Horn-Carroll theory explains the integration of processes such as: sensory input and processing, language comprehension, knowledge, and memory. This makes you think: is a person with profound deafness deprived from human intelligence? The topic has been discussed thoroughly in this paper. The answer is no, depending on the extent that the teaching, and upbringing of that person depends on auditory stimuli. A similar case applies to someone who does not have any sort of academic knowledge – he is not deprived of human intelligence. Or even people with amnesia (impossibility to recall memories), they are not deprived of human intelligence. Some people may disagree with me. To discuss this deeply, we would need to branch from psychology and neuroscience to the social sciences to understand how societies define people with conditions like these…. topic for another post!

Given the nature of the “simple” cognitive processes that integrate intelligence (perception, attention, memory, planning, etc…), it is possible to assess intelligence with standarized tests. The result of such tests is called the Intellectual Quotient (IQ) score. IQ scores have been correlated with a list of other characteristics, such as: brain size, job performance and, income. Remember, correlation only means that we see a relationship between the two factors that we are looking at, but it does not necessarily mean that the one causes the other (read one of our past blog posts on this topic). Please note that the IQ score only estimates global intelligence and has been tested in a gross sample of population without adjusting for known impairments. As any test, it has its drawbacks (e.g. strong verbal component, which would not make an accurate and reliable measure for people with blindness and/or deafness) and cannot be used alone to diagnose cognitive disability. Further refining has to be performed to assess IQ in people with sensorial disability and memory impairment. The biological basis of how IQ is “high” in some individuals and “low” in others remain to be investigated.

Until now, everything has been a bit theoretical, let’s talk brains! Research on intellect has found its milestones in the advances of neuroscience and neurological patient care. Since it was discovered that the brain is the house of all higher mental processes, many efforts to map where these processes take place have been made. Take for instance, the homunculus (from the latin little person), which is a map of brain areas that govern motor and sensorial function of specific body parts (see image below)

Sensory input and aphasias

When it comes to intelligence, language plays an important role in sending and receiving messages. Aphasia is a medical condition in which the individual cannot comprehend or formulate language, sounds crazy doesn’t it?! Usually these individuals suffer from some sort of brain injury, such as a stroke (most common, abrupt interruption of blood flow to a specific tissue mainly caused by a blood clot). Imagine that suddenly you can understand everything you hear, but whenever you talk people only hear gibberish from you; or, you cannot read a book because the letters do not make sense. Cases of patients like these, have allowed neuroanatomists to link specific brain areas to the language function. For instance Broca and Wernicke aphasias were mapped to the now called Broca and Wernicke areas, respectively, after Dr. Paul Broca (1824-1880) and Dr. Carl Wernicke (1848-1905). Patients with aphasia are not cognitively impaired.

Memory, learning and the patient HM

Henry G. Molaison, who we are going to call HM, was a teenager when he started experiencing major seizures that disrupted his academic performance, social life, and prevented him from working and functioning independently. In 1953, a lobectomy (a surgical extirpation of a brain lobe), was performed on the area that was mapped to be causing the epilepsy with the aim to cure his seizures. After he woke up, his seizures diminished dramatically, but a new condition popped up: he could not remember the hospital staff or his daily routine. Extensive tests revealed that his IQ was even above average and his cognitive, and language abilities were not affected. Further testing over the upcoming years revealed that HM was unable to consolidate new memories after the surgery. He would not recognize his caretakers or recall any autobiographical memories from the time of the surgery onwards, instead he would strongly rely on his memories previous to the surgery and general knowledge.

At the time, the biological basis of memory was not established. It was pretty well-accepted that memories are scattered in all areas of the brain. The case of HM demonstrated that the extirpated area: the hippocampus (in the temporal lobe) has a crucial role in memory consolidation and learning. He became the most studied patient in modern neuroscience. Thanks to his willingness to be studied, we now know of various aspects of memory that were impossible to study at that time. Memory research has advanced incredibly. Many other types and functions of memory have been described when studying psychiatric and neurologic conditions!

My field of research, Alzheimer’s Disease (AD) research, has a special focus on the hippocampus as it is one of the most affected brain areas. Patients with AD have progressive deficits in various types of memory that pile up until it causes Mild Cognitive Impairment (MCI). Perhaps I should write something on the whole classification of memory and AD diagnosis. What do you think?

What is known and what is yet to be discovered about human intelligence?

Regarding the biological basis of learning and intelligence, research has zoomed-in up until the neuron-neuron interaction (synapse) to show how memories are consolidated in a process called long-term potentiation (LTP). However, to put these processes into the context of a human being is a tough challenge. As is trying to explain what the difference is between a brain of a “high IQ” and a “low IQ” individual.

Gross anatomy has also continued reaching important milestones. Actually, in 2018, a new brain area was discovered: the endorestiform nucleus. It is thought that this area is unique to humans as it is absent in our closest evolutionary cousins, chimpanzees. It makes you think that there is still some room for discoveries in the old-fashioned way: just like Dr. Broca or Wernicke.

In the AD field, it remains as an open question whether therapies will improve cognitive performance and/or bring back some memories to the affected patients once there was neuronal loss.

It is very well-accepted that intelligence, as an abstract concept, is complex, integrative, and has evolved to what it is nowadays. It was not discussed here, but intelligence comes in all colors and shapes. For instance, Gardner’s theory of multiple intelligences explains that people do not have the same affinities and abilities for problem-solving (see below). Also, the concept of emotional intelligence has risen as an integration of cognition (all the concepts I outlined to you) and emotion, which consists of emotional self-awareness, inter-personal relationships, problem solving and stress-tolerance. It was shown that the “emotional quotient” (EQ; to assess emotional intelligence) associates with mental and physical health.

This is a bit of what makes us human: intelligence. I think that there are many important traits of human intelligence that I could not address here. Knowing what kind of processes take place in our mind, will ultimately help us know ourselves more. At the end of the day, you have to know the machine you are working with. #ScienceOfProductivity