  Chapter 

1.1 What is psychological science?

The aim of contemporary psychology is to understand mental activity and behaviour in humans. A psychologist tries to understand and predict the mental activity and behaviour and he looks at how people are being influenced by individual, social and biological factors. People are intuitive psychologists who try to understand and predict the behaviour of others, however, conclusions drawn based on intuition are often wrong. The science of psychology refers to research on the mind, the brain and behaviour. Mind is the mental activity, such a thoughts, feelings and perceptions. For example, when you are smelling fresh baked cookies you might think about times when you were a child helping your mother baking cookies. Mental activity is the result of biological (chemical) processes within the brain. The association between mind and brain has been discussed for years. Behaviour refers to observable actions in which humans and animals can engage. For a long time, behaviour was seen as the only objective measurement of the mind. The purpose of psychology is to understand mental activity, how people react differently to social situations and how to teach people healthy and unhealthy behaviours.

Psychology and critical thinking

One of the aims of this textbook is to learn to think more critically. A critical attitude is required towards all kinds of information, especially information that seems logical. Scientists have to learn to be sceptical. Critical thinking involves systematic questioning and evaluation of the information at hand. It is important to ask critical questions and not to take information for granted. Often seemingly logical explanations are used for certain phenomena, for instance that listening to Mozart’s music makes babies more intelligent. Research has shown that this is not true. Critical thinkers have to look for alternative explanations of behaviour. Critical thinking involves looking for alternative explanations, detecting weak use of evidence and the use of logic. In addition, it is important to be open to new information and to examine whether a study might be influenced by personal or political interests. Also, think whether the used research designs are appropriate.

Psychological reasoning

Psychological reasoning refers to drawing conclusions with regard to people’s thinking on the basis of psychological research. There are several ways in which one can have biased reasoning.

Confirmation bias: people evaluate information that is similar to the beliefs they already had as more positive. At the same time, they underestimate the value of information that is different from their own ideas.

Source reliability: the reliability of the information source should always be questioned. Reliability of a source might overestimated due to authority (information about one’s health is seen as more reliable if it is provided by a physician compared to a random neighbour).

Misunderstanding statistics: people have generally difficulties in using statistics accurately. Gamblers believe that a roulette ball that has landed on a red 5 times in a row is now more likely to land on black, however, this probability does not change. Also the fact that your aunt is smoking for more than 40 years without lung cancer does not mean that there is no relationship between smoking and cancer. The relationship between smokers and cancer is that smokers are more likely to get cancer, not every smoker gets cancer.

Seeing relationships that do not exist: it is often assumed that if two things happen at the same that they should be related to each other which is not the case. Often it is just a coincidence.

Using relative comparisons: how a question is framed, or presented, also changes how people answer the question. People tend to prefer information that is presented positively rather than negatively. For example in medical treatment, people feel more positive about a treatment if they know about the survival rates than if they know about how many people do not survive the treatment.

After-the-fact explanations (hindsight bias): people often come up with explanations for why events happen, also when they have incomplete information. Evidence is reinterpreted in a way that it fits better to the outcomes, as a result, existing evidence becomes biased.

Mental heuristics: heuristics are decision rules that are followed to decrease the effort that it takes to make good decisions. However, using heuristics can also lead to more inaccurate decision making.

Self-serving bias: People want to feel good about themselves, therefore, they think that they are better than average on a variety of aspects. To support this positive view, people credit personal strengths for successes whereas they blame outside forces for their failures. People also have difficulty recognizing their own weaknesses.

1.2 what are the scientific foundations of psychology?

Psychology originated in philosophy, in which the great thinkers tried to understand the human nature. In the 19th century, psychology became an own discipline with different schools of thought that would dominate the field for a period of time.

Nature-nurture debate

The nature-nurture debate already started with Greek philosophers, such as Aristotle and Plato. The question is whether psychological characteristics are biologically determined or caused by the environment, for example by culture. Culture refers to the attitudes, norms and beliefs that are important within a group of people who share their language. These factors are transmitted from one generation to the next. The result of the debate is a compromise, namely, there is always an interaction between genes and environment.

Mind-body problem

In the past, it was thought that the mind was located in the organs of the body, for example in the heart or in the liver. In the following ages, people realized that the mind would be essential for mental functioning. This insight originated in the observation of people with brain damage. The mind-body problem involves the question whether the mind and the body exist separately from each other or that the mind a subjective experience of the brain is. Early philosophers thought that the mind and body functioned separately from each other. Leonardo da Vinci was one of the first who attempted to connect mental functions to different brain areas. Around 1500, he made anatomical drawings of brains. He believed that sensory information would arrive in a certain brain area called ‘sensus communis’. In this area, all kinds of thinking would take place. Around 1600, Descartes introduced another interpretation, which is called dualism. Dualism refers to the idea that the mind functions separately from the body, however, the mind and body are connected. The body was viewed as an organic machine that was led by reflexes. The other way round, many psychological functions, such as memory and imagination would be products of the body. This was a very controversial idea. Descartes thought that the body could affect the mind and vice versa. He was the first who believed in an interaction between mind and body.

The start of psychology: introspection

The topics studied in contemporary psychology are not new, since Greek philosophers asked themselves the same questions as psychologists do nowadays. Physicists from the ancient times were wondering whether brains would be important for mental activity. In China, in the third century B.C., assessments were used to select people for certain jobs. Muslim authors in the ninth century B.C. emphasized the importance of therapy and development of children. Century’s later, psychology would develop into an experimental science. In 1843, Mill states in his book ‘

System of Logic’ that psychology should use observation rather than philosophical reasoning after which a revolution took place. Psychology was no longer about speculation but about carrying out experiments. In 1879, Wundt established the first psychological laboratory. He is seen as the founding father of experimental psychology. He introduced the principle of mental reaction times that an individual would need for a simple and a complex task. He thought that the difference between the time needed to accomplish a simple and a complex task, would be the time that the mental effort would cost. He wanted to measure conscious experiences as well. This was done by introspection: the study of subjective mental experiences in which (trained) individuals had to describe their thoughts. After some time, introspection was being rejected because it is subjective and not representative.


Titchener, one of Wundt’s students, used introspection as a foundation for his own new idea, namely, structuralism. This school of thought is based on the idea that conscious experiences can be divided in underlying basic elements. Titchener believed that the mind could be understand if one knew the underlying elements of consciousness. For instance, the quality, intensity, duration and pureness of music could be analysed with the use of introspection. Wundt rejected this way of using introspection.


James was a physicist with a philosophical interest in the mind. His ideas were of great influence on psychology. He was one of the first professors who wanted to have more interaction with his students during lectures. He was also very interested in the origination of conscious experiences. Therefore he had a critical attitude towards structuralism. He believed that it was not possible to divide the mind into different elements because the mind is way too complex. According to James, the mind existed of a never ending stream of thoughts that continually changed, called stream of consciousness. He thought that structuralism was as trying to study a house by looking separately at every brick. According to James it was more important to know how the mind and behaviour were of influence on adaptive functioning. This approach is called functionalism. The mind came into being by evolution. Apparently, the mind is of importance in survival and reproduction. Knowledge from functionalistic research should be applicable on problems that we face in daily life. Functionalism was strongly criticized and became less popular. Today, the relevance of functionalism is recognized.

Gestalt psychology

Gestalt psychology arose because of all the critics on structuralism. The founding fathers of gestalt psychology are Wertheimer and Kohler. According to the Gestalt theory, the whole is more than the sum of its parts, which also applies to personal experiences. The subjective experience is not just the sum of its different elements, which was thought by strucuralists. For instance, if you see a circle with two pints and a line beneath it, you might think it is a face although there is minimal evidence that it is actually a face. The sum (the circle, points and line) is less than the whole picture (seeing the face). Gestalt psychologists are doing experiments with normal, untrained people. The phenomenological method refers to reporting the experiences of people in a unstructured way. In this approach, subjective conscious experiences are important, which are different among individuals.


In the twentieth century, the ideas of Sigmund Freud became popular. Freud started his career as a neurologist and he worked with people suffering from neurological diseases. He believed that their conditions were caused by psychological factors. He also believed that behaviour was elicited by unconscious mental processes. Freud thought that disorders were caused by the unconscious (mostly sexual) conflicting mental forces. In psychoanalysis, it is tried to make the unconscious conscious in order to solve psychological conflicts. Solving these conflicts was done with the use of dream interpretation and free association. Free association means that the patient is encouraged to speak freely about everything that pops up in his mind. although these ideas were very popular in the beginning, nowadays very few psychologists support these ideas. Freuds theory is not scientifically testable and the methods, such as dream analysis, are subjective. Nevertheless, the idea that mental processes take place out of awareness, is widely accepted.


Because the mental processes describe by Freud are very difficult to study, behaviourism came into being. Watson was the most important founding father of behaviourism and he thought that mental processes should not be studied because they are not directly observable. According to behaviourism, all kinds of behaviour are evoked by the environment (nurture). Every action is a response to a certain stimulus and it can be predicted by the stimulus. Skinner did not believe that behaviour was determined by mental processes, he viewed mental processes as an illusion. Skinner thought that behaviour was determined by the consequences of certain actions. He looked especially at the consequences of reinforcement and punishment. Behaviourism became very popular because many people were unsatisfied with the vagueness of psychoanalysis. Until 1960, behaviourism was dominant but afterwards the focus shifted again towards mental processes.

Cognitive psychology

The results of several studies made behaviourism less popular. Gestalt psychologist Kohler discovered that monkeys were able to grab a banana that was out their scope by putting to sticks together in order to reach the banana. The monkeys showed this solution because of a sudden insight or because observation but not as a result of reinforcement or punishment. In addition, a growing amount questions could not be answered from a behavioural perspective, for instance, how the human development was influenced by cultural aspects. These factors led to a cognitive revolution initiated, among others, by Miller.

Cognitive psychology refers to the study of higher mental functioning, such as intelligence, thinking, language, memory and decision making. From cognitive research it became clear that thinking influences behaviour. at the same time the computer was introduced. Cognitive psychologists, such as Simon and Newell, were fascinated by computers and tried to explain the working of the mind by the working of computers. The information processing theories perceive the brain as the hardware and the mind as the software. The brain codes information, processes the information, save the information and retrieve it when necessary. The cognitive psychologists were initially interested in the software (the mind) but around 1980 their interest for the hardware grew. In this time cognitive neuroscience arose, which is focused on the brain and the nervous system as underlying mechanisms of thinking, learning, perception, language and memory.

Social psychology

After the second world war, many new research questions arose. Psychologists became interested in the question why so many people had obeyed in the war. Social psychology studies these questions on authority, obeying others and group behaviour. it is studied how people develop a social identity through interactions with others and how this social identity influences the way people response to others. From research it is know that people are strongly influenced by social situations. Lewin, Gestalt psychologist, made from social psychology a scientific and experimental field. His field theory emphasizes interactions between people (their genes, habits and beliefs) and their environment.

Humanistic movement

Humanists such as Rogers and Maslow emphasize that an individual has to get to know and accept himself in order to reach self-actualisation and to treat psychological disorders. They developed therapies with the aim that people would use their full potential. The therapy existed especially of asking specific questions and listening. Over time, different methods to treat psychological problems were developed. These methods all represent different schools of thought that were dominant in a certain period of time. in behaviourism, techniques to treat problematic behaviour were developed. In cognitive psychology, techniques to treat problematic thoughts were developed. During the biological revolution, more medicines were developed. Medicines do not replace therapy, they can have side-effects and can be addictive. Often a combination of medicines and therapy is the best treatment. From the humanistic tradition, everyone is unique and has the right to get a tailor made treatment. Over time, it became clear that different people with different disorders need different treatments and that there is no universal treatment that suits everyone.

1.3 latest developments in psychology – biological revolution

Until a few decades ago, it was not possible to answer questions about the connection between body and mind as there were no systematic methods. Nowadays, these questions can be better answered because there are more advanced methods available. We learn more about psychological and physiological processes of mental activity. For instance, the brain functions by means of neurotransmitters, which are messengers that transmit information between different neurons. There are about hundred different neurotransmitters, each having its own function in psychological processes. People remember things better if they are aroused than when they are calm because if they are aroused, more neurotransmitters facilitate the memory processes. Also, there is localisation within the brain, specific areas are relevant for specific thoughts, feelings and actions.

We learn also more about genetic processes. A map with all the human genes, the human genome is made. With the help of this map, it is tried to find a relation between certain genes and behaviour. it is studied how certain genes are influencing one’s thoughts, actions, feelings and difficulties. In animal research, genes are being manipulated to study the effects on psychological processes. It has been shown that if a mouse did not have a certain gene, its memory was restricted. This information can be used in the development of people with memory problems. the relation between genes and a certain psychological characteristic is complex: often there are more, interacting genes involved in behaviour. Moreover, genes interact with environment. The brain can be studied with the help of brain imaging techniques. With these techniques it is studied how and where different brain areas are located. Specific areas are responsible for certain functions but there is often interaction between the different areas. Brain imaging arose in the 80’s and changed psychology dramatically.

The evolutionary approach

James and his colleagues, who were all functionalists, thought that the human mind was shaped by evolution. From an evolutionary perspective, the brain, brain activity and resulting behaviour have evolved over millions of years. Evolution theory views the brain as an organ that is evolved in order to make survival and reproduction of the human species. In psychology, mental traits are seen as products of natural selection. Functions such as memory, perception and language can be seen as adaptations. Adaptations are facial characteristics, skills or other actions that increase the likelihood of reproduction and survival, therefore, they are inherited to the next generations. There is growing evidence that the brain adapts biologically and that the mind adapts under influence of culture. Adaptations are caused by gen mutations. These physical characteristics, skills or abilities contribute to the solution of a certain adaptive problem, therefore, the probability that they will be given to the next generation is high. Through natural selection we received build-in mechanisms that solve adaptive problems from the past. The evolutionary perspective is important in the explanation of social behaviour. behaviour that leads to exclusion is disapproved in almost all cultures. Another example is that everyone has his own food preferences, however, these are influenced by one’s culture. According to the evolutionary perspective, we should look at the function of behaviour in the past in order to find an explanation for contemporary behaviour. the brain evolves very slow. This means that a characteristic that was useful a long time ago, in the hunter-gatherers time, is still present, although not useful anymore. In the past, sweet foods with a lot of calories were scarce. This kind of food had a great survival value and a preference for fatty and sweet foods was adaptive. Nowadays, people still have this preference but it leads to maladaptive behaviour, as it can make people obese. There are also many behaviours that are not caused directly evolutionary. For example, driving a car or exercising to intentionally offset calorie intake does not reflect evolutionary heritage but is displayed only recently.

Culture provides adaptive solutions

Culture can also be seen as adaptation. It is adaptive for people to be in a group because of protection. Living in groups causes the development of culture. Culture is also influenced by the principles of evolution: what is adaptive in a certain culture is determined by environment. Cultural evolution goes much faster than biological evolution. In the last century, great changes have occurred in how people interact. The flow of people, commodities, and financial instruments among all regions of the world are referred to as globalization. Also the internet has created a new form of culture. According to Nisbett, members of Asian cultures think more holistically that members of western cultures (that is more individualistic). People from Asia think less analytically compared to people from Europe and North America. These difference might be caused by a different history. The culture in which one is living is determining the norms and beliefs someone has. Norms specify which behaviour is expected from the people living in a certain culture. Culture contains also material aspects such as media, technology, health care and transportation. These factors are of influence on how people interact with each other. psychologists try to understand the relation between culture and behaviour.

Levels of analysis

Many psychologists work together with researchers from other field, such as biology, physics or anthropology. A question is divided in sub-questions and studied within the appropriate research field. The focus lies on social, individual and biological approaches. There are different levels of analysis which are described here by use of an example study on influence of music.

The social approach looks at:

  • Interpersonal interaction: groups, relations, social influence.

  • For example: do groups determine which influence music has on somebody?

The cultural approach looks at:

  • Thoughts and behaviour within a culture: norms, beliefs, symbols and ethnicity.

  • Ethnomusicology: does culture determine which music people like?

The individual approach looks at:

  • Individual differences: personality, development, self-concept.

  • Perception and cognition: perception, thinking, deciding, language and memory.

  • Behaviour: observable behaviour, reactions and movements.

  • For example: which effects has music on mood, memory, deciding etc.?

The biological approach looks at:

  • Brain systems: neuro-anatomy, animal research, brain imaging.

  • Neurochemistry: neurotransmitters, hormones and medicines.

  • Genetics: gene mechanisms, heritability.

  • For example: do different brain areas become active if music is presented than when other sounds are presented?

Different fields

Psychologists are working in different fields which are described here:

Neuroscientists and biologists study the influence of biological systems on mental activity and behaviour.

Cognitive psychologists look at how people think, perceive, solve problems, make decisions, use language and learn new skills.

Developmental psychologists study the development of individuals during the life-span.

Personality psychologists are interested in traits of people and how these traits differ per context. They also look at differences between individuals.

Social psychologists try to understand how people are influenced by the presence of others and how people perceive others.

Cultural psychologists study how people are influenced by societal norms that belong to a certain culture.

Clinical psychologists study factors that might cause psychological difficulties and they search for treatments.

Counselling psychologists try to improve daily well-being of people. The difference with the clinical psychologist is that a counselling psychologist is more focused on a difficult situation in which on is currently rather than treating psychological disorders.

School psychologists are working in education where they help students with learning difficulties.

Industrial and organizational psychologists study behaviour and productivity at work. for example, motivation is studied.

Psychologists are working in many more fields such as forensic settings or sports. Health psychologists are working interdisciplinary and they study factors that influence ones physical health.

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