Glossary

Acclimatization

A reversible adjustment of the body to a new environment, such as altitude or heat, over days or weeks. It differs from genetic adaptation across generations. Read: How Humans Adapt to Extreme Environments

Algorithm

A step-by-step procedure for solving a problem or making a decision. In everyday use it often means the ranking or recommendation rules that sort what we see online. Read: How Technology Competes for Human Attention

Artificial intelligence

A field of computer science building systems that perform tasks associated with human intelligence, such as recognizing images or language. Today's systems are narrow and excel at specific tasks. Read: What Makes Human Intelligence Different From AI?

Attachment

A lasting emotional bond, studied first in infants and caregivers by John Bowlby and Mary Ainsworth. Later research extended the idea to adult relationships, with ongoing debate over how stable styles are. Read: Why Humans Need to Belong

Attention economy

An economic framing in which human attention is a scarce resource that products and platforms compete to capture, often to sell advertising. Read: How Technology Competes for Human Attention

Automation

Using machines or software to carry out tasks with limited human involvement. It tends to change which tasks within jobs people do, in addition to replacing some work. Read: Which Human Skills Matter in an Automated World?

Awe

An emotion triggered by something vast that challenges our usual way of understanding the world. Studies link it to feeling small and more connected, though many are lab-based. Read: Why Awe Can Change How We See Everyday Life

Circadian rhythm

A roughly 24-hour cycle in body processes such as sleepiness, temperature, and hormone release. It is driven by internal clocks and adjusted by cues such as light. Read: Why Humans Sleep—and What Scientists Are Still Discovering

Cognitive load

The amount of mental effort being used in working memory at one time. When demands exceed capacity, attention and accuracy usually suffer. Read: Why We Get Distracted

Commensality

The practice of eating together at a shared table or meal. Researchers study it as a way food and company shape relationships and group identity. Read: How Shared Meals Bring People Together

Confirmation bias

The tendency to seek, notice, and remember information that fits what we already believe, and to scrutinize conflicting information more harshly. Read: Why Humans Believe Things That Are Not True

Creativity

The ability to produce ideas or work that are both original and useful or meaningful in context. Definitions vary, and what counts as creative depends on the community judging it. Read: From Cave Art to Digital Worlds: The Human Urge to Create

Cultural transmission

The passing of behaviors, beliefs, and skills between individuals or generations through teaching, imitation, and language, as opposed to through genes. Read: Why Humans Tell Stories

Culture

The shared knowledge, practices, values, and artifacts that people in a group learn from each other. It is learned and transmitted, not inherited biologically. Read: Why Humans Tell Stories

Cuneiform

A writing system made by pressing a reed stylus into clay, developed in Mesopotamia by the late fourth millennium BCE and used for several languages for about three thousand years. Read: How Writing Transformed Human Memory

Deliberate practice

Focused, effortful training aimed at specific weaknesses, usually with feedback. Anders Ericsson popularized the term; its overall power to explain expertise is debated. Read: How Humans Learn to Do What Once Seemed Impossible

Digital literacy

The skills needed to find, evaluate, create, and communicate information with digital tools, including judging whether a source is reliable. Read: Which Human Skills Matter in an Automated World?

Divergent thinking

Generating many possible answers or ideas for an open-ended problem. It is one component of creativity tests but not the whole of creative work. Read: From Cave Art to Digital Worlds: The Human Urge to Create

Domestication

A long process in which people and another species become interdependent, leading to heritable changes in the plant or animal. It unfolded gradually and in several regions. Read: What Changed When Humans Began Farming?

Empathy

The capacity to share in or understand another person's feelings. Researchers often separate emotional sharing from perspective-taking, since the two can come apart. Read: Why Humans Need to Belong

Entrainment

The synchronizing of movement or physiological rhythms to an external beat or to other people. It is studied in music, dance, and group activity. Read: Why Music Matters Across Human Cultures

Eudaimonia

An ancient Greek term, central to Aristotle's ethics, often translated as flourishing: living well by developing virtues and acting on them, not just feeling pleased. Read: What Makes a Life Feel Well Lived?

Flow

A state of deep absorption in a challenging task, described by Mihaly Csikszentmihalyi. It is usually measured by self-report, which limits how firmly it can be studied. Read: How Humans Learn to Do What Once Seemed Impossible

Habit

A behavior triggered automatically by a context after repetition. Research suggests habits form on a variable timetable, so no single number of days applies to everyone. Read: Why Change Feels Difficult Even When We Want It

Hedonic well-being

Well-being defined by pleasant feelings and satisfaction with life. Researchers often contrast it with eudaimonic well-being, though the two are related. Read: What Makes a Life Feel Well Lived?

Heuristic

A mental shortcut that lets us make quick judgments with limited information. Heuristics are often useful, but they can produce systematic errors in some situations. Read: Why Humans Believe Things That Are Not True

Hominin

A member of the human lineage after it diverged from the line leading to chimpanzees, including Homo sapiens and extinct relatives such as Homo erectus and Neanderthals. Read: How Humans Spread Across the Planet

Homo sapiens

The species to which all living humans belong. The oldest fossils generally assigned to it come from Africa and date to roughly 300,000 years ago, though classification is debated. Read: How Humans Spread Across the Planet

Human-in-the-loop

A design in which a person reviews, corrects, or approves what an automated system does, keeping human judgment in the process. Read: Which Human Skills Matter in an Automated World?

Hypoxia

A shortfall of oxygen reaching the body's tissues. It occurs at high altitude, where air pressure is lower, and triggers physiological responses such as faster breathing. Read: How Humans Adapt to Extreme Environments

Illusory truth effect

The finding that statements feel more believable after repeated exposure, partly because familiarity is easy to mistake for accuracy. It has been shown in many lab studies. Read: Why Humans Believe Things That Are Not True

Iteration

Repeating a cycle of making, testing, and revising so that each version improves on the last. It is central to engineering, design, and science. Read: What Failure Really Contributes to Invention

Large language model

A machine learning system trained on large amounts of text to predict and generate language. It can produce fluent answers, but fluency is not a guarantee of accuracy. Read: What Makes Human Intelligence Different From AI?

Loneliness

The distressing feeling that one's social connections are fewer or less satisfying than desired. It is a subjective experience, and it can occur even among people who are often around others. Read: Why Loneliness Can Exist in a Crowded World

Machine learning

A method in which software improves at a task by finding patterns in data rather than following only hand-written rules. Read: What Makes Human Intelligence Different From AI?

Meaning in life

A sense that one's life has significance, makes sense, and is directed toward goals. Psychologists commonly describe it as having coherence, purpose, and significance. Read: Why Humans Search for Meaning

Misinformation effect

The tendency for information encountered after an event to alter a person's memory of it. Elizabeth Loftus and colleagues documented it in studies beginning in the 1970s. Read: Why Your Memory Is a Reconstruction

Multiple discovery

The same discovery or invention arising independently in different places at similar times, as with calculus, suggesting ideas often emerge from shared prior knowledge. Read: The Hidden Teams Behind Famous Breakthroughs

Narrative

An account of connected events, real or imagined. Anthropologists and psychologists study narratives as a way people explain events, pass on values, and build shared identity. Read: Why Humans Tell Stories

Need to belong

The proposal, associated with Baumeister and Leary (1995), that humans have a strong drive to form and maintain lasting, positive social bonds. It is an influential theory rather than a settled law. Read: Why Humans Need to Belong

Neolithic

An archaeological period associated with farming, herding, and settled villages, beginning at different times in different regions. Dates vary widely from place to place. Read: What Changed When Humans Began Farming?

Neuroplasticity

The nervous system's ability to change its connections and function in response to experience, learning, or injury. It continues throughout life but varies with age. Read: Why Movement Matters for Learning and Everyday Life

Oral tradition

Knowledge, stories, and law passed between generations by speaking rather than writing. Many oral traditions use rhythm, song, and structure to support accurate remembering. Read: How Writing Transformed Human Memory

Play

Voluntary, intrinsically motivated activity pursued for its own sake. Games add rules and goals to play and often link it to competition and status. Read: Why Humans Turn Games Into Serious Competition

Present bias

The tendency to give extra weight to rewards and costs that arrive soon compared with those that arrive later, even when we would judge the later outcome as more important. Read: Why We Procrastinate Even When We Care

Procrastination

Voluntarily delaying an intended task despite expecting to be worse off for the delay. Researchers treat it largely as a problem of managing emotions and short-term pull, not of poor time management. Read: Why We Procrastinate Even When We Care

Prototype

An early, rough model built to test an idea before committing to a final design. Prototypes make flaws visible cheaply. Read: What Failure Really Contributes to Invention

Purpose

A stable intention to work toward goals that matter to you and that extend beyond yourself. It is one commonly studied part of meaning. Read: What Makes a Life Feel Well Lived?

Radiocarbon dating

A method that estimates the age of once-living material by measuring remaining carbon-14. It works for samples up to roughly 50,000 years old and needs calibration against other records. Read: How Humans Spread Across the Planet

Reciprocity

The practice of responding to another's action with a similar one, such as returning a favor. Reciprocal exchange is a recurring feature of social life documented across many societies. Read: How Trust Is Built, Broken, and Repaired

Reconstructive memory

The view that remembering rebuilds an event from stored fragments plus current knowledge and expectations, instead of replaying a recording, which makes memories vulnerable to change. Read: Why Your Memory Is a Reconstruction

REM sleep

A sleep stage with rapid eye movements, vivid dreaming, and brain activity resembling wakefulness. Its precise functions are still under investigation. Read: Why Humans Sleep—and What Scientists Are Still Discovering

Ritual

A patterned, symbolic action performed in a prescribed way, often with social or spiritual meaning. Rituals appear in every known society, though forms vary enormously. Read: How Shared Meals Bring People Together

Rumination

Repetitive, passive dwelling on the causes and consequences of distress. It differs from active problem-solving because it tends to circle without producing a plan, and it is linked in research with low mood. Read: Why Humans Overthink—and What Helps Us Break the Loop

Serendipity

Finding something valuable by chance while looking for something else. Chance helps mostly when a prepared observer recognizes what the surprise means. Read: What Failure Really Contributes to Invention

Sleep pressure

The growing need for sleep that builds with time spent awake and eases during sleep. It works alongside the circadian rhythm to time sleepiness. Read: Why Humans Sleep—and What Scientists Are Still Discovering

Evaluating our own abilities, opinions, or circumstances by measuring them against other people. The idea was formalized by Leon Festinger in 1954. Read: Why We Compare Ourselves to Other People

An objective lack of contact or few social relationships. It is distinct from loneliness: a person can be isolated without feeling lonely, or lonely while well connected. Read: Why Loneliness Can Exist in a Crowded World

An unwritten rule about what behavior is expected or acceptable in a group. Norms are enforced through approval, disapproval, and habit. Read: How Shared Meals Bring People Together

Status quo bias

A preference for keeping things as they are, even when a change would be beneficial, partly because losses feel larger than equivalent gains. Read: Why Change Feels Difficult Even When We Want It

Time perception

The brain's subjective sense of how long events last. It can diverge from clock time and is influenced by attention, novelty, emotion, and age, though the mechanisms remain debated. Read: Why Time Seems to Speed Up as We Get Older

Trust

A willingness to be vulnerable to another person or group based on positive expectations about their intentions or behavior. It can be built gradually and damaged quickly. Read: How Trust Is Built, Broken, and Repaired

Urbanization

The growth of towns and cities and the share of people living in them. Early cities, such as Uruk in Mesopotamia, arose independently in more than one region of the world. Read: Why Humans Built Cities—and What Cities Changed

Values

Principles that a person cares about and wants guide their choices, such as honesty or curiosity. Clarifying values is a common step in many approaches to behavior change. Read: What Makes a Life Feel Well Lived?

Terms