Eighteenth- and nineteenth- century precursors to a scientific psychology - summary of chapter 3 of Historical and conceptual issues in psychology, by Brysbaert, M and Rastle, K (second edition)

Foundation of Psychology
Chapter 3
Eighteenth- and nineteenth- century precursors to a scientific psychology

Individualisation of Western society

A characteristic of current Western society is that people derive their self-image and self-esteem from their own qualities and accomplishments rather than from the position of their family in society.
Individualisation: trend in a society towards looser social relations and a greater focus by individuals on themselves than on the groups they belong to.
Historians believe that this process of individualisation started sometime around the end of the Middle Ages and is still growing.

Following factors are contributions:

• Increased complexity of society
  Increasing diversity in occupations and complexity of social relations
  Increased urbanisation and industrialisation put people into more complex and competitive social networks, in which everyone struggled to maintain a sense of dignity and meaning.
  As the number of occupations and trades grew, people felt a greater need to position themselves relative to others.
• Increased control by the state
  Society gathered and stored more and more information about its individuals, which was reported back to the citizens. This information gathering gave people the feeling of standing out of the crowd.
• Individuality promoted by Christianity
  This religion puts an emphasis on the solitary individual, because each person’s private state of faith and religion to God is the essence of piety.
• Mirrors, books and letters
  • The presence of a mirror in the house made people more aware of themselves and the impression they made on others
  • Printing further enhanced the interest and fascination for others.
    Novels had more depth in characters
  • As literacy increased and postal services improved, letter writing became more common and was no longer limited to formal messages. ‘Familiar letters’ became a way to explore, express and share intimate experiences.

Interim summary

Since the end of the middle ages there has been increasing individualisation in society. Factors hypothesised to play a role include:

• Increased complexity of society
• Increased control by the state
• Individuality promoted by Christianity
• The increased availability of mirrors, books and letters

Philosophical studies of the mind

Descartes was the first Western philosopher after the Ancient Greeks to value new and independent thinking.
Epistemology: branch of philosophy concerned with the nature of knowledge.

Empiricism instead of rationalism

The traditional rationalist view

The traditional view of understanding in philosophy was based on rationalism.
Rationalism: view according to which knowledge is obtained by means of reasoning; usually through deductive reasoning on the basis of innate knowledge.

Empiricism

As natural philosophers developed the scientific method, observation and inductive reasoning gained importance.
Empiricism: view according to which knowledge is obtained by means of perceptual experiences; usually involves the idea of association between ideas to combine the individual perceptions; also emphasis on inductive reasoning.
The human mind at birth is a black slate (a tabula rasa) on which experiences leave their marks and make associations with the marks already present.

Interim summary

Rationalism

• Existence of innate knowledge (nativism)
• Reason is the source of knowledge
• Main research method: deductive reasoning
• Main applications: logic, mathematics
• Main proponents: Plato, Descartes, Leibniz

Empiricism

• No innate knowledge (tabula rasa)
• Perception is the source of knowledge
• Main research methods: observation, experimentation, inductive reasoning
• Main applications: natural sciences
• Main proponents: natural philosophers, Locke, Berkeley, Hume

Epistemology in troubled waters: idealism

Although John Locke is generally considered to be the father of empiricism, his writings were rather cautious.

• He was aware of the limits of perception
• Despite the image of a black slate, he did not really promote the idea of a human mind without any innate potential

Berkeley and Hume

It didn’t take long before other philosophers took up Locke’s idea of the mind as a black slate and showed that it could lead to far-reaching, counter-intuitive conclusions.

George Berkeley (1685-1753)
If the contents of the soul entirely consist of impressions acquired through observation, then we have no guarantee, except for God, that the contents of the soul are a faithful rendition of the world.
We have no guarantee that there exists something like an outside world. The contents of the mind could be fully self-generated.
The method of observation promoted by the men of science did not necessarily lead to a true understanding of the world. It could be equally well suited in one grand illusion.
Idealism: view within philosophy that human knowledge is a construction of the mind and does not necessarily correspond to an outside world; the truth of knowledge depends on the coherence with the rest of the knowledge in the social group.

Realism: view within philosophy that human knowledge tries to reveal real properties of the outside world; the truth of knowledge is determined by the correspondence of the knowledge with the real world.

David Hume (1711-1776)
Pointed out that idealism questioned the scientific endeavour of unearthing causes and effects.

• Because causes are never observed directly, we derive them from experiencing the co-occurrence of phenomena.
  The mind simply infers causality from co-occurrence (contiguity) in time and place.

When we experience he co-occurrence of events, we tend to see one event as the source of the other.
This gives us an illusion of deeper knowledge beyond senses and memory, but actually there is no guarantee that something in the world corresponds to our postulated causal relationship.
We assume that our impression of causality is due to the existence of a cause-effect relationship in the outside world, which we have discovered, but from an empiricist perspective there is no guarantee for such an assumption. The link could arise entirely form the mind alone.

Hume pointed to a second principle humans use to group sensations, association by similarity.
Because two sensations resemble each other, we assume they come from the same entity in the world.
Again, there is no guarantee that this is true.

Kant

Immanuel Kant (1724-1804)
Kant agreed with Berkeley and Hume that we cannot have direct knowledge of the outside reality (the thing-in-itself) through perception.

Humans not only perceive, they also thing about their perceptions.
By combining input from their senses with understanding, they come to concepts and judgements that generalise across the perceived instances and go beyond basic experiences.
In doing so, the mind adds knowledge (to sensations) that is not derived from the observation itself and, hence, can be considered innate.
The most important types of knowledge added by the mind to incoming stimuli

• Time
  Because there is continuity in the understanding and the perceptions, the mind can conclude that there must be continuity in time both for the observer and the observed.
  As a result, perceptions are automatically situated and ordered in time.
• Space
  Because sensations are experienced as caused by something ‘outside’, there is a sense of space that need not be learned and leads to the postulation of perceptions referring to substances situated in space
• Cause-effect
  The mind puts forward the assumption that ‘every event has a cause’. As a result, the mind sees cause-effect sequences wherever possible.

Human perception could not arise in an environment completely at odds with the sensations.
Even if sensations are subjective, they can only exist if the perceiver inhabits a world that is in line with the input from the senses.
Successive sensations must form continuity and unity to be understood, otherwise they are experienced as incoherent and meaningless snapshots.
Humans do not have direct access to their experiences.

All they can observe is the objects of their experiences and these objects require stimulation that remains constant in time (that continues to exits when unobserved).

Humans are not merely centres of knowledge, they are also agents, operating in the environment on the basis of their knowledge.
Not all of these actions are successful, suggesting that an outside reality constrains human activities.

Scottish common sense

Thomas Reid (1710-1796) argued that it was time for a return to what he called ‘common sense’.
Perception was a direct interaction between the perceiver and the real object, and did not result in a separate stage of perceptual representations, which may or may not be a truthful copy of the outside world.

Rational and empirical psychology

As philosophers became ever more interested in the human mind, the theme ‘psychology’ was added as the fourth part of metaphysics.
Metaphysics: the study of the nature of the universe.

Wolff

Christian Wolff (1679-1754)
Wolff took ideas from Aristotle, Bacon and Newton to define the subject of psychology.
First, he defined rational psychology very much as Aristotle had done for theoretical knowledge.

• It started from axioms (self-evident truths), which had to be derived from more fundamental disciplines, such as physics and metaphysics.

On the basis of deductive reasoning, these axioms would lead to the ‘demonstration’ of new knowledge.
This rational approach guaranteed true conclusions about the human soul and allowed the philosopher to penetrate more deeply into the matter than by simple observation.

Wolff agreed with Bacon that pure reason without observation entailed risk of error. Long chains of reasoning without reality checks invited mistakes.
So, psychology needed a close interaction between reason and observation, or empirical psychology.
Empirical psychology according to Wolff was built on introspection.
Introspection: research method in psychology consisting of a person looking inward and reporting what he/she is experiencing; usually done under controlled circumstances.
In his view, the human mind could perceive its own operations and use this information to build a science of psychology.

Wolff suggested that psychology should aim for mathematical demonstrations. Only then would there be full understanding.
He called this approach ‘psychometrica’.

Kant again

Kant contemplated the issue of ‘psychology’, as part of this struggle to integrate rationalism and empiricism.
In doing so, he came to a conclusion that was pretty devastating for the scientific ambitions of psychology.

• Kant made the distinction between empirical and rational knowledge.
  • The empirical approach led to a collection of facts which could be ordered and classified.

This led to ‘a historical doctrine of nature’, which was below the level of natural science
Natural science required rational analysis, a system of un-disputable axioms and demonstrations.
A proper natural science required the axioms and demonstrations to be written as mathematical laws.

Kant’s objections can be summarised as follows:

• The outcome of introspection cannot be formulated in mathematical terms because there are no aspects of substance or space in inner observations, only time
• Inner observations cannot be separated and recombined at will, as is possible with outside objects
• The act of introspection by itself changes and displaces the state of the observed mind
• As a result, psychology can never become a natural science (let alone a proper natural science). It can at most be a historical doctrine of nature, a collection of systematically ordered empirical facts.

Comte

Auguste Comte denied psychology the scientific status of psychology.
Psychology was excluded from his hierarchy of sciences because of the problems with the introspective method.
The only ways in which the human mind could be studied scientifically, according to Comte, was on the basis of biology and the basis of observation of the products produced by the mind.

Interim summary

Psychological studies of the mind

Epistemology

• Rise of empiricism (Locke), which questioned the traditional rationalist view
• In its extreme form empiricism leads to idealism, as argued by Berkeley and Hume
• Kant sought to reconcile rationalism and empiricism by arguing that the mind imposes structure on the incoming sensory experiences and that it requires a coherent and constant input to make sense of input
• Idealism was also put aside by Scottish common sense

Rational and empirical psychology

• Psychology was added as the fourth part of metaphysics
• Important impetus: two books by Wolff, who made a distinction between rational psychology (based on axioms and deductions) and empirical psychology (based on introspection)
• Kant argued that psychology could not be a proper natural science, because of the act of introspection changed the state of the mind, inner observations could not be separated and recombined at will, and could not be formulated in mathematical laws
• Comte argued that introspection as a scientific method was flawed and claimed that the human mind could only be studied scientifically by focusing on physiology and the products of the human mind

Textbooks of psychology

Because of psychology’s increasing impact within philosophy, a growing number of psychology courses were taught at university, not only to philosophy students, but also to students of religious and educational studies.
This created a marked for text-books on psychology, which shaped people’s views.

Kant

Kant published a textbook on human functioning, ‘Anthropologie in pragmatischer Hinischt’, based on the lecture notes of a course he was teaching.
Kant did not treat the topic as a science, but as a collection of narratives. Nor did he call the subject psychology, but anthropology.

Kant devoted a part of his book to deriving people’s characters from their appearance and behaviour.
Physiognomy: belief that the personality of an individual can be deduced from their appearance, in particular from the shape of the head and face.

Herbart

Johan Friedrich Herbart (1776-1841)
His book ‘Lehrbuch zur psychologie’ was written in particular for use in educational studies.
Herbart was convinced that knowledge of psychology was for principal importance to teachers.

Upham

In the United States, students had to take courses on moral and mental philosophy.

• Moral philosophy dealt with ethics and conduct
• Mental philosophy studied the elements and processes of the mind and how they influenced action.

The contents were heavily influenced by Scottish common sense realism, but increasingly took a distinctive American look with locally produced books.
A particularly popular textbook was ‘Elements of intellectual philosophy (1827)’ by Thomas Upham (1799-1872)
Upham’s book starts with:

• Intellectual philosophy is a science
• It differs from the previous, worthless education in Roman Catholic schools
• Studying it is not a waste of time

Bain

The United Kingdom saw an impressive series of psychology-related textbooks published.
Arguably the most influential were two books published by the Scottish philosopher and educationalist Alexander Bain (1818-1903).

• The senses and the intellect (1855)
• Emotions and the will (1859)

These books formed the template of nearly all subsequent English psychology textbooks.

An important new element Bain introduced was the inclusion of physiology in his books.

Interim summary

The increased importance of psychology has resulted in the production of textbooks since the late 1700s, which illustrate the themes considered important and which also influenced people’s views of psychology. Four books have been discussed:

• Kant: Anthropology as a collection of observed facts about humans
• Herbart: Attempt to make psychology scientific by introducing mathematical laws
• Upham: Claim that intellectual (mental) philosophy is a science worthwhile to be studied
• Bain: Introduction of the nervous system and other physiological information in a textbook of psychology

Scientific studies of ‘psychological’ functions

While philosophers in metaphysics were debating the status and contents of psychology, some natural philosophers started to run Baconian experimental histories that nowadays would be classified as psychology experiments.
In the second half of the nineteenth century, the findings of these experiments would encourage scholars to establish ‘laboratories of experimental psychology’.

Human perception

Given the importance of observation in natural science, it was normal for men of science to be interested in the possibilities and limits of (human) perception.
Quite a lot was already known about the topic before the scientific revolution.

Hooke

Robert Hooke (1635-1703)
Was interested in determining the minimal visual angle that could be discriminated.
This was important for the use of telescopes and later also determined the degree of detail that could be seen through the newly built microscopes, of which Hooke made extensive use.
On the basis of his studies, Hooke concluded that humans could discriminate lines that covered a visual angle of 1 minute of arc, a retinal wide of 0,0035mm.

Mayer

Hooke’s research was replicated and much extended nearly a century later by the German astronomer Tobias Mayer (1723-1762).
Mayer used more types of stimuli than Hooke had used.
He found that for black dots, the limit of vision was nearly half that of Hooke’s estimate while the limit of gratings was comparable to Hook’s estimate.
He also observed that the relationship between the distance of a candle and the limit of vision was not linear but curvilinear.

Weber and Fechner

Ernst Heinrich Weber (1795-1878)
He was in the first place interested in tactile senses.
He published two treatises that would turn out to be highly influential for the history of psychology.
Weber ran two types of studies

• He used a compass with blunted points and briefly touched (blindfolded) people’s skin with them.
  When the points were far apart, people could clearly feel two different parts being touched.
  When the points were put closer together, from a certain point, people no longer had the feeling of two different parts being touched but an elliptic instrument containing them. When the points were brought even closer, from a certain distance on, it was experienced as a single round object touching the person.
  The minimal distance he called the ‘Two-point threshold’. He also discovered that this threshold is different for different body parts
• How good people were at discerning weights between the left and the right arm
  He put unequal weights in each hand and asked people which one was heavier
  For instance, he discovered that it was not the absolute difference between the weights that was important, but the ratio between them.

That was finding inspired Gustav Fechner (1801-1887) to develop a mathematical law connecting sensation magnitude to stimulus intensity.
Fechner realised that there could be a Newtonian mathematical function connecting the magnitude of the sensation to the magnitude of the stimulus.
Psychophysics: part of psychological research dealing with the relationship between physical stimuli and the corresponding sensation.

The speed of signal transmission in the nervous system and mental chronometry

The personal equation

Two main tasks of astronomers are:

• Precise measurement of the movements of stars
• Determination of the exact time on earth

Before the development of modern equipment with automatic registration, both tasks required a close coupling of clock reading and star-gazing.
This went reasonably well until 1796 when Nevil Maskelyne noticed that the times registered by his assistant were about half a second later than his.
The fact that people differed from each other in the time needed to register precise events became well established among astronomers and other men of science. As a result, scholars became interested in the time needed to transfer information in the nervous system and to perform simple mental operations.

Von Helmholz

Hermann von Helmholtz (1821-1894)
Started a series of studies to measure the speed of nerve impulses
By stimulating the nerve in a frog at a certain place and measuring the passage of the signal at several distances, he could estimate the conduction of speed of the nerve.
This meant that information transmission in the nervous system became measurable and had practical consequences.

Donders

Franciscus Cornelis Donders (1818-1889)
Wondered whether he could use a similar technique to measure the speed with which humans could perform elementary mental tasks.

Mental chronometry: using reaction times to measure the time needed for various mental tasks; on the basis of a comparison of different tasks, models of the mental processes involved in the tasks are postulated.

Interim summary

Characteristics and limitations of human perception and information processing interested the natural philosophers, who began to run Baconian experimental studies. They discussed two lines of research:

• Studies on human perception. The level of detail humans can discern (Hooke), the influence of illumination on this capacity (Mayer), the detection of just noticeable differences between stimuli (Weber, Fechner) and the formulation of a psychophysical theory based on them (Fechner)
• The time needed to perform tasks and the speed of signal transmission in the nervous system.
  Astronomers varied in their estimates of the timing of events (personal equation) and showed variability in them. Von Helmholtz could measure the transmission speed of nerves in frogs (and humans), Donders could measure the time needed for simple mental operations

Evolutionary theory

Darwin’s theory

The right zeitgeist

In hindsight, Darwin’s theory about the evolution of species was bound to be discovered around the mid-nineteenth century, most likely in the United Kingdom.

• Ever since Carolus Linnaeus had started his work on the classification of plants and animals in the eighteenth century, botanists from many countries had contributed to the enterprise, non more enthusiastically than the British.
• The taxonomy of biological species not only confronted the scholars with thorny issues about how to define distinctions and similarities, it also made them wonder how the diversity had originated.
• Around the same time, the first writings about fossils started to appear.
• In the 1840s the British prime minister replaced the tax on glass by an income tax.
  • One of the consequences was a vast proliferation of greenhouses in which exquisite, exotic and continuously evolving plants were cultivated.

Cross-fertilisation and natural selection

A first observation that struck Darwin was that, although many plants were capable of self-fertilisation, they seemed to avoid it.
If it happened, the offspring were on average less healthy.

• Cross-fertilisation produced variation in the offspring that was more vital and sometimes even resulted in the creation of a new type of flower.

Darwin was at loss to understand how the new offspring could start to dominate and eventually replace the old variety.
Darwin red and economic book and realised that the struggle for existence in a world of limited resources was the reason why some variants hand an advantage and started to outgrow the variants without that advantage.
Natural selection: process in Darwin’s evolutionary theory by which the environment results in the continuation and multiplication of organisms with certain genetic features and hinders the reproduction of organisms with other genetic features; the first type of features are called favourable (within the prevailing environment), the second type unfavourable.
Survival of the fittest: term introduced by Herbert Spencer to describe the outcome of natural selection: only organisms that fit within the environment and can produce viable offspring survive.

The origin of species: book by Charles Darwin (1859) in which he presented the evolutionary theory.

The dilution problem

Although the book was a instant success and led to lively debates, its initial impact was less impressive than we nowadays think.

• One element that Darwin failed to explain was how a single new plant or animal could come to dominate the rest
  This is the dilution problem.

Common misunderstandings of evolutionary theory

There is no direction in the genetic changes

All that happens is that the material now and then has a random alteration.
Most of these changes result in offspring that do not differ in an observable way from the parents.
Sometimes, a change results in a descendant that is barely to further generations.
Occasionally, an alteration results in a characteristic that is particularly well adapted to the prevailing environment and that increases the chances of the organism to survive and have descendants.
This new variant gradually increases in number at the expense of the variants without the characteristic.

Organisms do not become better or stronger

Just more likely to survive in a certain environment

An example of Darwin’s influence: Galton

Francis Galton (1822-1911)
Searched to find evidence for the argument that features were inherited.
He set out to measure human intelligence.

Interim summary

Evolutionary theory

• Proposed by Darwin
• Several developments made the theory likely in the nineteenth century: interest in diversity and correspondence between species, discovery of fossils, cultivation of new flower types
• Darwin discovered that random variations at birth, together with limited availability of resources, could explain evolution on the basis of natural selection
• Theory published in The origin of species
• Darwin could not explain how new random generated organisms could come to dominate the existing organisms

Common misunderstandings of evolutionary theory

• The mistaken belief that there is a direction in the genetic changes that cause the initial variation
• The mistaken belief that evolution results in better or stronger organisms

An example of Darwin’s influence: Galton

• Galton tried to find evidence for the heredity of animal and human features
• Was not very successful, but inspired subsequent generations to address the issue of intelligence testing.

The contribution of statistics

Psychological research requires the analysis of many observations to detect the underlying patterns

The development of statistics was another innovation of capital importance for the emergence of psychological research.
A crucial difference between physics and psychology is that processes in the former usually yield very much the same outcome each time they are repeated.
Because of the intrinsic variability in psychological (and biological) measures, it is not possible to get rid of the noise simply by trying to improve the accuracy of the measurement.

Quetelet’s contribution

Adolphe Quetelet (1796-1874)
Analysed crime statistics.
He was able to predict how many crimes there would be in the next year and which variables affected this number.
Statistics help to design a proper study

Statistics not only allowed researchers to analyse their data, they also provided them with information on how to design biological and behavioural studies, so that valid conclusions could be drawn.

Interim summary

• Research on living organisms required other data analysis than research in physics and chemistry, because the data were noisy and simultaneously influenced by many different factors
• Quetelet discovered that, whereas individual data points were impossible to predict, such prediction was possible when the analysis were based on the means of hundreds of observations
• Fisher further showed how researchers could adapt their methodology so that the influence of confounding variables could easily be factored out in statistical analysis