by Chris Woodford. Last updated: January 13, 2020.

Why do we do the things we do? Why do some people like hot chocolate while others prefer coffee? Why do some live to surf while others would rather stay home and read a book? How can some of us puta name to every single person we've ever met while others struggleeven to remember our own telephone number? Why do some peoplealways seem happy and successful while others see no choice but toend their painful lives in suicide? These are the sorts of questionswe can try to answer through psychology: the science of humanbehavior. In this short article, we'll briefly explore the differentbranches of psychology and get a quick overview of the kinds ofthings psychologists do.

Photo: Everything you do, think, and feel involves your brain, shownhere as a 3D-printed model. Understanding how the brain works, how it gives rise to the mind, and why it makes us do the things we do is the prime goal of psychology. Photo courtesy of Nevit Dilmen, NIH 3D Print Exchange, National Institutes of Health, published on Flickr under a Creative Commons Licence.

We can divide psychology into two big areas called experimental psychology and social psychology.

Of course, we can study social psychology in a lab using rigorousexperiments, just as we can carry out meticulous experiments in the real world; the division I've drawn between experimental and socialpsychology is arbitrary and artificial, but it reflects the waypsychology is often taught in schools and colleges, and how it'swritten up in textbooks and scientific papers. The reason for that islargely historical: in the late 19th-century, when psychology wasstill a very new field, psychologists were keen to be taken seriouslyas scientists, so they tried to adopt scientific methods to cloak thethings they studied in respectability. To this day, there's a certainstigma attached to social psychology and sociology (the study of howindividuals and groups behave in society); whether fairly or not,some people see them as soft sciences lacking academic rigor. AtCambridge University in England, for example, the psychologydepartment still calls itself the "Department of ExperimentalPsychology" and its curriculum includes relatively little socialpsychology.

Humans are the most complex of all the animals, which explains whypsychology is such a vast subject. Within the psychology departmentof a typical university, you'll find people working in a huge rangeof different areas. There are people who study perception (such ashow our eyes and ears work), learning (how we develop as children andhow we make sense of the world as adults), memory (why we rememberand how we forget), language, thinking, and reasoning. While somepsychologists study "normal" human behavior, others specialize in"abnormal" psychology, which includes how people behave whentheir brains are damaged or degenerate over time and what causespsychiatric disorders. Social psychologists study everything from thebest way to design a computer mouse to whether we can really trustthe evidence we get from people who witness crimes. Let's look at thevarious branches of psychology in turn, in a bit more detail.

You can think of people as living machines who receive information fromthe world, process it in various ways, and then act on it. In themid-20 century, it was fashionable to talk about animals (includingpeople) receiving a stimulus through their senses (maybe seeing achocolate-chip cookie appearing in front of you), which then led tosome kind of response (salivating and reaching out); according to aschool of thought known as behaviorism, human behavior was allabout the way a certain stimulus produced an appropriate response(and exactly what went on inside the brain to make the connectionwasn't thought to be especially important: behaviorism was literally"mindless"). Since the 1960s and 1970s, psychologists have tendedto view the human brain as a kind of computer, taking in informationas "input," processing and storing it in various ways, and thenproducing "output" (some kind of visible behavior); this approachis known as cognitive psychology and we'll consider it again alittle later. However you react to the world, your behavior usuallystarts with sensory perception: the way your five main senses(vision, hearing, smell, touch, and taste), plus other, lesser-knownsensory abilities such as proprioception (your sense of where yourlimbs are and how your body is moving), feed information into yourbrain.

Photo: A huge part of your brain is devoted to processing information gathered by your eyes.

For most people, vision is easily the most important sense, closelyfollowed by hearing; that also explains why perceptual psychologistshave traditionally devoted most effort to studying vision, closelyfollowed by hearing (comparatively speaking, the other senses havebarely been explored at all). Most of us assume that we see with oureyes, but it's far more accurate to say that we see with our eyes andour brains. While we can't see without our eyes, it's also true thatour brains carry out a huge amount of processing on the sensoryimpressions they receiveand in all kinds of interesting ways. Onevery obvious example is that we see things in three dimensions usingseparate, two-dimensional images that our brain fuses together fromour two eyes. But we also see things based on what we expect to see,which is what causes most of the things we call optical illusions;for example, we see faces in clouds because our brains try to makesense of the world very quickly based on the things we've seen in thepast (an awful lot of faces), the things we expect to see in thefuture (an awful lot more faces), and the things that matter most tous (the faces of people we love, work with, and have to interactwith). We can get some idea of just how complex the human visualsystem is by considering how little progress computer scientists androbot engineers have made designing machines that can "see" inanything like the same way. Why are our own brains so good at seeing?It's estimated that something like 30 percent of the cortex (the outer and,in evolutionary terms, "newest" part of the human brain) is devoted to vision. That's a veryimpressive illustration of the sheer complexity of making sense ofthe world entirely by studying light rays that enter two big holes inyour head.

One of the things that marks out humans from "lesser" creatures is ourability to make sense of our environment and learn from it. It'sobviously untrue to suggest that humans are the only creatures thatlearn things: you can teach a chimpanzee to use a symbolic language,you can train a dog not to defecate on your carpet, a rat willquickly learn to run through a maze to reach a food reward, and evena simple sea-slug can learna couple of basic tricks.

Learning goes hand-in-hand with survival, but it's a surprisingly large andcomplex subject. At one end of the spectrum, psychologists study theprocess of conditioning, which is how animals come toassociate a particular stimulus with a certain response. One ofthe first people to look into this was Russian scientistIvan Pavlov(18491936), who famously rang a bell when he delivered food to his dogs; eventually,he found the dogs would salivate simply when he rang the bell, evenwhen there was no food around, because they'd been conditionedto associate salivating with the sound of the bell. When behaviorismwas fashionable, some psychologists thought all kinds of complexhuman behavior might be broken down into patterns of stimulusand response. That's why, for example, you often see attempts toblame violence on TV and in the movies for wider violence in society.Now we know complex human behavior is much more than a simpleknee-jerk reflex from stimulus to response.

One of the great things about psychology, which differentiates it from oldersciences such as physics and chemistry, is that its relevance toeveryday life is often more immediate and apparent. One branch of thepsychology of learning is called developmental psychology andit concerns how babies develop into children and adults: for example,how they learn language, how they turn specific, concrete examples ofthings they see around them into much more general, abstractprinciples (the rules by which we have to live to survive), and therelative importance of "nature" (genetic factorsthings we'reborn with) and "nurture" (environmental factorsthings we'retaught and learn). Developmental psychology has played a huge role inpedagogy and the scientific, theoretical approach to education; it's also afascinating subject to study if you're a parent.

Photo: Mirror neurons? Sometimes we mimic one another's behavioral unconsciously, such as when two friends stand next to one another and, quite unawares, adopt exactly the same posture. Psychologists think our brains contain "mirror neurons," which are activated both when we do things and when we see other people doing those things. That encourages us to copy other people's behavior, and possibly explains how we feel empathy with others. Photo by Kasey Close courtesy of US Navy.

Thousands of years ago, before humans started to create fixed settlements anddeveloped agriculture, we lived much like other animals andday-to-day survival was our only preoccupation. How different thingsare now. Although the world's poorest people still experience life asa horrible daily battle to survive, most of us, thankfully, get tolead lives that alternate between (reasonably tolerable) work and(extremely tolerable) pleasure. Both of these things involve usingour brains as much as or more than our bodies; both see us functioningas living computers"human information processors"that take ininformation, process or store it in our brains, and then outputresults. The way we process and store information is what cognitivepsychologists study. How do we understand a simple sentence whisperedinto our ears? How can we remember everything from how to ride abicycle to the names, in order, of all the American presidents? And isthere any fundamental difference between these two types of memory(knowing how to do something, which is called procedural memory, andknowing facts about the world, which is declarative memory)?

Where behaviorists liked to pretend that "internal mental processes"didn't matter, didn't exist, or probably both, cognitive psychologists spendtheir time teasing out the precise nature of those processes,typically coming up with flowchart models that break such things asmemory and language processing (a field of its known, often known aspsycholinguistics) into sequences of discrete components.Applying this to the study of memory, for example, has given usmodels of mind that suggest memory breaks into separate long-term andshort-term stores, with the short-term or "working" memory itselfdivided into distinct areas that process visual impressions, snippetsof spoken language, and so on.

Artwork: Ulric Neisser's famous caricature of cognitive psychology from his 1976 book Cognition andReality.

Cognitive psychology is not limited to how we process the structure ofinformation, but also what information means. The word cognition is asynonym for thinking and reasoning, two areas that cognitivepsychologists have also studied using computational models. How do wemake informed judgements about things, such as whether one car is abetter buy than another? Why do we live in absolute fear of thingslike terrorist attacks but happily cross roads, drive cars, ridebicycles, drink alcohol, or smoke cigarettes (all of which pose fargreater risk to our safety and health)? Why do we play lotteries whenthe chances of winning are so much less than the odds of being struckby lightning? These are the sorts of questions cognitivepsychologists consider under the broad umbrella of thinking and reasoning.

Photo: The psychology of typography: Thanks to things you've read and seen previously, you read words printed in different fonts (typefaces) with a slightly different meaning and emotion: elegant, relaxed, friendly, imperative, hostile, or whatever it might be. You can emphasize a message you want to get across by choosing the most appropriate font. That's one of the key principles of graphic designand it happens in your mind, not on the page.

Though related to cognition, intelligence, which we might define as ageneral ability to solve problems, is a separate area of study, andit's much less fashionable than it used to be several decades ago.There are several reasons for this. FromSir Cyril Burt (a prominentBritish psychologist who allegedly faked research data about hisstudies of intelligence) toWilliam Shockley (the co-inventor of thetransistor who, predictably, became embroiled in controversy when hedared to suggest that there was a link betweenrace and intelligencethat made white people intellectually superior to blacks), the studyof intelligence has often proved intensely controversial. Thecontroversies, though important, distract from a much more fundamentaldifficulty: how should we define intelligence and is it even a meaningfulconcept? Some cynics have defined intelligence as the mere ability topass intelligence tests, but although psychometric testing isas popular as ever in recruitment for jobs, intelligence tests arenot, and never have been, a predictor of people's ability to livehappy, worthwhile, successful lives.

When you study psychology, it's remarkably easy to forget that most of thecool and fascinating things you discover happen inside the brainanapparently unremarkable organ often compared to "two fistfuls ofporridge." Neuropsychology is all about figuring out how the brainis structured and how different parts of it have different functions.One extreme, early example of neuropsychology, known as phrenology,famously involved quack doctors claiming they could tell interestingthings about someone's personality by feeling their skull for bumps.Although the idea seems risible today, the central idea ofphrenologythat the brain is modular, with discrete regions havingspecialized functionsis now known to be essentially correct.However, it's an unhelpful oversimplification to suggest, forexample, that the right half of the brain is dreamily creative whilethe left half is clinically rational; for most of the things we do,many different parts of the brain are involved, either working inparallel or in complex serial circuits.

Photo: Brain scanners have revolutionized psychology. By showing up the activity inside ourbrains when we think certain thoughts or do certain things, they can help to reveal which areas of the brain do what. Photo by courtesy ofWarren Grant Magnuson Clinical Center (CC) and USNational Institutes of Health (NIH) Image Gallery.

If cognitive psychology can break things like memory or language intoseparate areas or processes, is it possible to locate parts of thebrain where those things happen? That's the basic thinking behind ahugely successful field called cognitive neuropsychology,which involves trying to map abstract processes and functionsdiscovered through cognitive psychology onto very concrete areas ofthe brain that neuropsychologists have discovered (and vice-versa).Some psychologistsmodern-day mentalMercatorsget carried away in a frenzy to map the brain,forgetting that the ultimate goal is not to draw a tourist's guide to the insideof your head but to produce a scientific explanation of the mind: who we are andwhy we do the things we do.

While neuropsychologists do study healthy, functioning brains, they alsodevote a lot of their time to researching people whose brains havebecome damaged through such things as head injuries, strokes, ordegenerative diseases like Alzheimer's. We can discover much abouthow things like memory and language processing work by studying whatpeople can no longer do when specific areas of their brain aredamaged or destroyed. In the most spectacular cases, it's possible tofind people with very localized brain damage who can no longer dovery specific things (for example, recognizing faces or readingwords); we can infer from this that the damaged brain areas play akey role in whatever function has been lostand that helps us buildup a map of which parts of the brain do what.

People are hugely diverse and differentthat's one of the things that makeslife interesting. While it's difficult to define "normal"behavior, it's somewhat easier to point to examples of abnormalbehavior, which is harmful to people and those around them.Neuropsychological problems following brain injuries are one example,but behavior can also become abnormal for a wide variety of otherreasons, which we might broadly divide into behavioral, cognitive,and neurochemical/biological. Eating disorders such as anorexia andbulimia are believed to be largely behavioral and cognitive, forexample: you might develop an eating disorder if you convinceyourself you're fat, after becoming obsessed with skinny catwalkmodels. Illnesses such as Parkinson's disease are more to do withneurochemistry and biology: Parkinson's is believed to occur when nerve cells in the brainstop producing dopamine, an essential chemical neurotransmitter that sends messages around the brain.

Psychiatric disorders such as depression and schizophrenia are hugely complex andstill imperfectly understood. Depression can occur for many differentreasons, which might be behavioral (you feel nothing you do makes anydifference and become miserable through "learned helplessness"),cognitive (you analyze the world around you in a way thatpersistently makes you unhappy), neurochemical/biological (for onereason or another, the chemicals or the basic structure of your brainare geared to unhappiness), or some combination of these things. Thestudy of schizophrenia has a fascinating history, with attempts toexplain it shifting from anatomical/biological causes, through cognitive and behavioral ones, and back again. Originallydescribed as a kind of premature dementia ("dementia praecox"),by the 1960s it was being painted (by such figures as R.D.Laing) as akind of sane reaction to an insane world, and now it's much more likely tobe considered a consequence of a person's particular brain chemistry.

You'd think understanding the cause of a psychiatric problem would be thefirst step toward treating it but, remarkably, psychiatry has oftenworked in willful ignorance of what was happening in the mind, partlythrough the influence of behaviorism, partly through the challenge of anti-psychiatristswho refused to believe in what they called the"myth of mental illness," and also because the underlyingcauses of psychiatric problems were genuinely not known. Treatmentsfor psychiatric disorders were largely doled out on the basis of whatseemed to work and what didn't; if clinical trials found that drugscured more depressive patients than, say, group therapy (talkingabout your problems with other patients), drugs became the treatmentof choice. It didn't necessarily matter why they worked or how,providing the patients showed an improvement. That's how hugelycontroversial psychiatric treatments such aslobotomy (surgicalremoval or destruction of parts of the brain, also called leukotomy) andelectroconvulsive therapy(electrical shocks to the brain) became popular in the mid-20thcentury. Just as psychology tried to cloak itself in experimental andscientific rigor, so 20th-century psychiatry latched onto therespectability of medicine, often masking a substantial ignorance ofhow and why disorders actually occurred. Today, thanks to advances inneurology, neuropsychology, and neurobiology, we have a much clearerunderstanding of how the brain works and why it can malfunctionbutmany questions remain.

Photo: Psychologists are helping computer scientists to develop emotional robots like this one, pictured at Think Tank, the science museum in Birmingham, England.

In the 150 years or so since psychology became a science, hugeamounts have been discovered about why people behave as they do andhow we can relate different aspects of human behavior to what goes oninside our heads. Even so, teasing out the many, remaining mysteriesof the brain remains one of the last great challenges of science.Apart from being hugely interesting in its own right, anotherimportant prospect is the discovery of effective treatments forterrible degenerative diseases such as Parkinson's and Alzheimer's. Afurther interesting direction is the development of artificialintelligence, including computers and robots that can "think" andact in more humanlike ways. Will probing the mysteries of the mindhelp us perfect electro-mechanical rivals who make us obsolete? Orwill the act of developing intelligent machines sharpen our sense ofwhat it means to be human, making us happier and more fulfilled?Psychologists, you can be sure, will find the answer!

Read more from the original source:
Psychology: An introduction to the science of human behavior