What is intelligence?

Intelligence refers to the intellectual functioning that compares a person's intelligence quotient (IQ) with other people of the same age. In other words, it is the ability to understand circumstances or situations and arrive at appropriate solutions. Both animals and plants exhibit intelligence.

In general, intelligence represents the ability to learn, understand or deal with adaptive behaviors within an environment. Intelligence can also be called by terms such as the brain, brainpower, emotional knowledge, creativity, problem-solving, grey matter, headpiece, intellect, intellectuality, mentality, sense, smartness, logic, understanding, and self-awareness.

Smartness is about using the obtained knowledge and applying it to situations, while intelligence is about gaining knowledge or information and using it efficiently to procure or produce solutions.

An image that shows the elaborated version of the acronym SMART line by line. Here, S denotes Specific, M denotes Measurable, R denotes Relevant, and T denotes Time-bound.
Full-form of the acronym SMART

In the word SMART, S refers to specific. It states that smart people carry over their works precisely.

M refers to measurable. It states that people, who are considered smart, ascertain the importance and value of everything and act accordingly.

A refers to achievable. It means that people viewed as smart achieve what they aim to finish.

R refers to relevant. It states that people viewed as smart didn’t do any irrelevant works apart from their ideas.

T refers to time-bound. It states that smart people work with a fixed deadline or within a specified period (week, month or year).

Increase in intelligence

The IQ of an individual can change over time. With age, a person gathers more knowledge and experience and his crystallized intelligence improves. Training ones' memory, executive control, and visuospatial reasoning can help boost a person's intelligence level.

Boosting intelligence

Research has established that intelligence in individuals can be enhanced over the years through several activities.

Various factors that increase the intelligence level include

  • Regular exercise: Exercise increases the volume of the hippocampus, which is involved in memory or information retention. It also promotes the growth of neurons and boosts brain structure and function.
  • Enough sleep: Sleep is an essential factor that improves cognitive functions. When a person sleeps, his brain consolidates the memories created throughout the day.
  • Meditation: Meditation increases an individual’s attention, memory, recognition ability and mood.
  • Consumption of coffee: Caffeine and antioxidants are two important ingredients of coffee. These components affect the brain positively by increasing alertness and concentration and improving mood. Caffeine blocks adenosine which is a brain chemical that stops the release of stimulatory substances.
  • Consumption of green tea: Green tea improves brain function as it contains a small amount of caffeine.
  • Other activities that enhance intelligence levels include eating nutrient-rich food, playing an instrument, reading, learningand socializing.

Definitions of intelligence

There are many definitions of intelligence, some of which are contradictory to each other. Some of the psychologists suggested various definitions of intelligence.

Here, a few definitions of intelligence are provided for better understanding.

  • Alfred Binet defined intelligence as judgement (also called good sense), the capability of adapting one’s self to adjust to different circumstances.
  • David Wechsler defined it as the aggregate capacity of the individual to act purposefully, think rationally and deal effectively with their environment.
  • Lloyd Humphreys explained intelligence is the process of acquiring, storing and retrieving memory, combining, comparing and using in new contexts information and conceptual skills.
  • Linda Gottfredson stated intelligence as the ability to deal with cognitive complexity.
  • Robert Sternberg explained it as goal-directed adaptive behavior.


The word 'intelligence' is derived from the Latin noun 'intelligentia' and verb 'intelligere.' During the Middle Ages, 'intellectus' was the technical term used for better understanding. The term 'intellectus' is strongly linked to metaphysical and cosmological theories of teleological scholasticism, the mortality of the soul, and the concept of active intelligence.

Human intelligence was briefly studied in the 1800s, where Sir Francis Galton, a cousin of Charles Darwin, was one of the study members. Galton was interested in studying 'gifted individuals.' He set up a laboratory to study the reaction times and other physical characteristics and hypothesized that intelligence is a general mental ability derived from biological evolution. His study on intelligence paved the way for further research and studies on human intelligence.

Human Intelligence

Intelligence is humans' intellectual power (processing or showing intellect or mental capacity), marked with high levels of motivation and self-awareness. It enables humans to remember the descriptions of past events and use/remember them for future reference. Human intelligence permits thinking, reasoning, reading, learning, remembering, gaming and drawing.

Intelligence is based on heredity; it is fixed at the time of birth. And intelligence lends cognitive abilities to humans for:

  • Learning
  • Understanding
  • Reasoning
  • Planning
  • Problem-solving
  • Generating ideas
  • Using language for communication
  • Attention
  • Long-term memory
An image shows the flowchart of the factors arranged in horizontal line that influence human intelligence direction and the factors are written as knowledge, quantitative reasoning, visual-spatial processing, working memory, and fluid reasoning.
Factors affecting human intelligence

Intelligence is different from learning. Learning is the acquisition of knowledge or skills through study or experience, while intelligence is the ability of an individual to act cleverly and appear smarter than others.

Intelligence can be quantified through an IQ test. However, some people reject this test stating that it does not measure intelligence correctly.

There is an argument about the hereditary or environmental basis of human intelligence. If human intelligence is based on environmental factors, it can be changed throughout a person's lifetime. The cognitive abilities of humans are based on environmental factors such as reading, learning and puzzle-solving.

Emotional and social intelligence are subdisciplines of human intelligence introduced to convey one’s emotions or concerns to others or oneself.

Emotional intelligence is the ability of an individual to convey his emotions to others in an understandable way and identify others' emotions accurately.

Social intelligence is the ability of an individual to understand the motivation and social cues (signaling someone through facial expressions or body language) of others and oneself.

An image of concentric circles shows the factors associated with emotional intelligence. The outermost circle is labeled performance, well-being and emotional and social functioning. The second circle from the outside is labeled interpersonal, decision-making, stress-management, self-perception and self-expression. The third circle from the outside is labeled interpersonal, relationships, empathy, social responsibility, problem-solving, reality testing, impulse control, flexibility, stress tolerance, optimism, emotional expression, assertiveness, independence, self-regard, self-actualization, emotional and self-awareness.
Emotional intelligence and its factors

Animal Intelligence

Scientists have conducted various experiments on non-human animal intelligence. These experiments involve studying the mental ability of an organism and comparing it to the mental ability of other organisms or species. These studies measure factors such as problem-solving and numerical and verbal reasoning abilities. The main provocation in this area is that the definition for both human and non-human animal intelligence is the same. For example, Wolfgang Kohler’s research on apes and Stanley Coren’s book on the intelligence of dogs.

Other animals, especially chimpanzees, bonobos, dolphins, elephants, parrots, rats, and ravens, are well-noted and studied for their intelligence.

G-factor in other organisms

Many pieces of evidence show that non-human animals exhibit the general factors of intelligence. The general factor or g-factor is the psychometric construct used to study the correlation between the cognitive abilities of individuals with several other organisms. The g-factor was first identified in humans and later studied in many non-human animals.

Several studies have proved that the g-factor is responsible for 47% of individual variance measured in primates and nearly 55 to 60%in mice. These variables are equivalent (40 to 50%) to the accepted IQ variance of humans.

Plant Intelligence

Many researchers state that plants must also have intelligence since they can sense the changes in internal and external environments and adjust their morphology (structure), physiology and phenotype. By doing this, they protect themselves from harsh external factors and improve their reproduction potential.

Botanical science in biology suggests that plants are sensitive, and they use problem-solving skills to find energy, reproduce and regulate diverse environmental stressors. Plants thus have the ability to solve their problems. For example, when there is sunlight, plants undergo photosynthesis to prepare food. And in the absence of sunlight, they produce energy using alternative ways.

Plants have taken a different route to supply energy themselves. Animals aid plants in their reproductive process. Flowering plants release pollen that attracts animals through smell or color. The animals then transport these pollens to another plant as the animals migrate from one place to another. Plants can also produce toxic components to evade predators. When an insect attacks a plant, it releases specific chemical compounds in its leaf to attack them.

Common Mistakes

Students may misunderstand self-worth and intelligence. Self-worth is a sense of one’s own value as a human being, whereas intelligence is the mental ability of an organism to adapt itself to different environmental conditions.

Context and Applications

This topic is significant in the professional exams for undergraduate, graduate and postgraduate courses, especially for:

  • Bachelor of Science in Biology
  • Master of Science in Biology
  • Bachelor of Science in Criminology
  • Bachelor of Science In Brain and Cognitive Science
  • Bachelor of Science in Computation and Cognition
  • Master of Science in Cognitive Science
  • Master of Science in Neuroscience
  • Neuroscience
  • Cognitive Science
  • Cognition
  • Artificial Intelligence

Practice Problem

Q1: Intelligence is normally distributed in the population and it indicates that:

(a) Most people have an extremely low intelligence level

(b) Most people have an extremely high intelligence level

(c) Most people lack intelligence

(d) Most people have an average intelligence level

Correct choice: (d)

Q2: Which of the following is an example of bodily-kinesthetic intelligence?

(a) Dancer

(b) Artist

(c) Teacher

(d) Scientist

Correct choice: (a)

Q3: Intelligence can be quantified through ____.

(a) Physical test

(b) Knowledge test

(c) IQ test

(d) Quiz

Correct choice: (c)

Q4: Biologist, farmer, and gardener is an example of which type of intelligence?

(a) Interpersonal intelligence

(b) Musical intelligence

(c) Linguistic-verbal intelligence

(d) Naturalistic intelligence

Correct choice: (d)

Q5: Which of the following best describe the word musical intelligence?

(a) Excellent at thinking patterns and rhythms

(b) Exploring relationships and daydreaming

(c) Exploring the environment

(d) Physical movement and motor control

Correct choice: (a)

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