Gustav Theodor Fechner

Authors: Sukhmani sengar, Andrea Cretu, Manvir Singh Judge, Gulay Emin, Eden Barr, Carter Little

December 14th, 2018


Gustav Fechner (1801 - 1887)

Gustav Fechner was born in a small town in Germany where he graduated from medical school (“New World Encyclopedia,” 2017). He was interested in physics and later on was known as the founder of psychophysics. He has underlined the key concepts of physics through his research and by becoming a professor at the University of Leipzig in Germany. Between the many published books and articles, a contemporary book, “The Elements of Psychophysics” is well perceived as the study of the relationship between physical stimulant and mental response. The book portrays his new theories that are discovered and based on physics. His work is still studied today to understand the experiments and thoughts he had once found and displayed. While he continued conducting new studies and teaching, he experienced an eye illness which resulted in a long period of bed rest. Once Fechner was able to recover, he connected himself to God and began to study philosophy. At last, Fechner became closer to philosophy and continued to pursue this passion through books and lectures.


University of Leipzig

University of Leipzig, where Fechner both studied and taught for numerous years

Gustav Theodor Fechner was born in a village in Gross Särchen, Germany on April 19,1801 (“Encyclopedia Britannica,” 2018). His father died when he was young. Later on, Fechner enrolled himself in the university of Leipzig in 1807. He had received his medical degree in 1822 but decided not to pursue medicine, instead began to write satire (“New World Encyclopedia,” 2017). He later invested his interest in mathematics and began to study physics. After being knowledgeable in his work, he was known as a German physicist and philosopher who was a key figure in the founding of psychophysics. He published his own books related to psychology and physics.

In 1834, within a year after his marriage, Fechner was appointed as a physics professor at the University of Leipzig in Germany (McGill, Moose & Rehn, 1999). Several years after being a professor, he developed health issues as he began to experience more than usual exhaustion. In 1839 he fell ill with an eye illness of partial blindness due to his frequent gazing at the sun during one of his studies (McGill, Moose & Rehn, 1999). Fechner was isolated and off work for a few years due to which depression followed him.

By 1842, he began to recover and soon after he started to study philosophy and discussed the idea of consciousness (“Encyclopedia Britannica,” 2018). Later on, Fechner reached to experimental aesthetics where he determined what shapes and sizes were aesthetically most pleasing (“Encyclopedia Britannica,” 2018). From here on, he spent most of his time doing public lectures and later on he died at the age of 86 in November 18, 1887 (“Encyclopedia Britannica,” 2018).

Published books and the Importance of Elements of Psychophysics

Element of Psychophysics, Written by: Gustav Fechner

Element of Psychophysics, Written by: Gustav Fechner

Gustav Fechner can be considered an important individual in psychology as well as physics and philosophy for his work with psychophysics. This finding can be described to be the quantitative relationship between a physical stimulant and the mental response and sensation. (“New World Encyclopedia,” 2017) Psychophysics will be explained further into detail later. Much of his research and time as a physicist was spent studying this theory and further developing it. As Fechner concluded his work associated with psychophysics he published various papers to explain and support the developed theories.

During his time, Fechner had written various prevalent papers to accompany his findings, the most notable being, “Elemente der Psychophysik, 2 vol (Elements of Psychophysics)”. This book was first published in 1860, establishing the importance of experimental psychology and creating the first view and explanation of the theory of psychophysics. The published book created a name for Fechner in the field of psychology as he was accounted as one of the founders of modern experimental psychology. (“Encyclopedia Britannica,” 2018) His research not only developed a new theory but allowed the field to be studied in a way never experienced before; experimentally and quantitatively. Procedures in psychology using experimental and quantitative techniques he developed are still used today. In the book, Fechner included an equation to aid his explanation of psychophysics, more specifically the theory of just-noticeable differences. This theory was originally created by Ernst Heinrich Weber and further developed by Fechner. (“New World Encyclopedia,” 2017) His work with psychophysics helped the field of psychology be understood not only as a qualitative but also quantitative science.

As Fechner further delved in his findings, he continued to publish papers to follow his findings. Some additional papers include, Vorschule der Aesthetik in 1876, which explained the basic principles of art, Das Büchlein vom Leben nach dem Tod (The Book of Life After Death, 1836), Uber die physikalische und philosophische Atomenlehre (The Physical and Philosophical Atomic Doctrine, 1855) and more. (“New World Encyclopedia,” 2017)

Key Accomplishments

Fechner conceptualized that mind and body, though appearing to be separate articles, are actually different sides of one single reality. He also advanced experimental procedures which are still useful in experimental psychology for measuring sensations in relation to the physical magnitude of stimuli. Philosophically Fechner defended a monism in which the one world can be seen in one way physically and in the other mentally (“Encyclopedia Britannica,” 2018). Experimentally he sought to confirm this vision by discovering close quantitative relationships between conscious experience and physiological stimulus, as a result, discovering the law that the intensity of a sensation increases as the log of the stimulus conceptualizing psychophysical relations. This law proved the existence of evidence-based connection between body and psyche. This formula was named the Fechner-Weber law, because it based on the theory of the just-noticeable difference, advanced earlier by Ernst Heinrich Weber. He developed experimental procedures for measuring sensations in relation to the physical magnitude of stimuli (“Gustav Fechner,” n.d.). He proposed the three methods of measurement were the method of just-noticeable differences, the method of constant stimuli, and the method of average error. According to the authorities, the method of constant stimuli, called also the method of right and wrong cases, has become the most important of the three methods. In philosophy he was also an animist, maintaining that life is manifest in all objects of the universe. Fechner called his conception Day Vision, unlike his contemporary materialism – Night Vision (“Markov, S.” 2018, September 30). His greatest achievement was in the investigation of exact relationships in psychology and aesthetics. He demonstrated that since the mind can be measurable and understood mathematically, it is possible calculation in psychology. He hoped to organize psychophysics and metaphysics in a way that united philosophy and the human sciences. In 1865 Fechner’s interest turned to the study of the basic aesthetic principles of art (“Gustav Fechner” 2014, April 02). Fechner’s experimental method became the basis for experimental psychology and later inspired Wilhelm Wundt, who created the first scientific Psychological laboratory.

Sigmund Freud regarded Fechner as the pioneer of psychophysics and a founder of scientific and experimental psychology. He attended Fechner’s lectures in Leipzig in 1874. He gave him him the title “The great G. T. Fechner.” William James, who did not care for quantitative analysis or the statistical approach in psychology, dismisses the psychophysical law as an “idol of the den,” the psychological outcome of which is nothing (“Markov, S.” 2018, September 30).

Psychophysics and the Different Experiments Done in Order to Prove Physical Stimuli and the Mental Aspect of Psychology

Weber-Fechner Law Demo

Above is an example of the Just-noticeable differences explained by the Weber-Fechner law. In the picture, there are four images containing different amount of dots. The bottom two pictures have 10 additional dots than its the corresponding picture from above. Between the left two pictures, where the images have 10 and 20 dots respectively, there is a visible difference. In contrast, on the two pictures from the right, the pictures contain 110 and 120 dots. When comparing those two images they look almost identical at first glance. This illustrates a just noticeable difference which is explained in the section below. Image retrieved from Wikipedia.

Gustav Fechner did not have your typical scientific ‘upbringing’. Most scientists experiment with other and work together with teams in order to further their research and findings. After an accident where Fechner almost essentially blinded himself for research, he isolated himself from society for approximately three years, this is when he made his largest discovery of psychophysics (Markov, 2018). His initial curiosity began with philosophy, he believed that mind and matter are the same thing, rather than ‘mind vs matter’; this was his main solution for the ultimate philosophical problem according to Fechner. His hypothesis for this solution was “mind and body are not regarded as a real dualism, but are different sides of one reality” (Eval, 2018). Psychophysics is essentially the study of the relationship between mental experiences and physical stimuli (Eval, 2018). Fechner had taken Ernst Weber’s discovery of the extent of magnitude of one specific stimulus results in a noticeable change in sensations. Fechner applied Weber’s law to his research and finding, connecting them to the measurement of of sensations related to to a stimulus (Markov, 2018). This is what we now call the ‘Fechner - Weber Law’. This law both helps quantitative psychologists and philosophers withy the belief that the measurement of sensations are in relation to a measured stimulus (Eval, 2018). He came up with three different methods of measurements; just-noticeable differences, the method of constant stimuli, and the method of average error (Eval, 2018). Surprisingly enough, Fechner did not do any initial experiments per say in order to come up with his theory, he simply dreamt it and then pursued it. Ten years later, he wrote his book ‘Elements of Psychophysics” which explains his theory more in depth.

After many hours of research, it was very difficult to come across experiments that Fechner had done in order to help prove his hypothesis and findings. This may be due to the fact that he started with a philosophical view, which then he was able to connect to different aspects of physics in which he was teaching. His methodology conflicted with pure data that should have been done in order to prove his hypothesis and ideas more clearly. The correlation however to psychophysics and physical stimuli and the mental aspect of psychology has to do with the fact that they all relate to how much of a stimuli we can detect and how we can then detect the differences between stimuli in the environment with our sensory systems, including vision, auditory, taste, smell, and pain (Eval, 2018). An example of this being eating a nice cold watermelon on a hot summer’s day. The sensation of eating this good, cold watermelon then relays back to our brain which essentially what psychophysicists have been wondering. The relation between something we are doing and the different processes that can occur as a response.

Contemporary Assessments on Fechner’s Impact

*Article written on Fechner's impact and work with Psychophysics*

In modern times, multiple psychologists have looked back on Fechner’s work and discussed his crucial importance to the development of the field. Many articles have been written which discuss his impact as well as what has become of psychophysics since the era of Fechner. The article “The Place of Psychophysics in Modern Neuroscience” by J.C.A. Read of the Institute of Neuroscience at Newcastle University discusses where psychophysics has gone since Fechner, as well as if the work of early psychophysicists and their ideas are still relevant. Read argues that while the small groups of human subjects generally used for psychophysical studies may seem to come up with unreliable results, it is still just as important to study humans as it is to study animals (which has become a common practice since the creation of psychophysics because multiple subjects can be used). The article also discusses technological advancements and how they have and can further the role of psychophysics and take research beyond where it has ever been before. The invention of technology such as computers has helped early psychophysical ideas become modernized and be improved for use in modern psychophysics. Read states that early ideas of human psychophysics are not without their issues. For example, early psychophysics generally focused on judgements that were restricted to small sets of quantitative data, which don’t necessarily display the full picture of how the human brain interacts with physical stimuli. Despite this, Read does believe that the ideas of early human psychophysics are still of relevant in the world of psychology and neuroscience today (Read, 2015).

Another article, “Fechner: 150 years of Elemente der Psychophysik” by David K. Robinson, celebrates the 150th anniversary of Fechner’s revolutionary book on psychophysics. Robinson discusses the sheer importance of Fechner in not only the creation of psychology but also it becoming known as its own science. After Fechner’s work, other scientists began to take their own steps, using Fechner as inspiration, to further this new branch of science. Wilhelm Wundt, inspired by Fechner, opened up what is known by many as the first ever psychology lab, with psychological study being its sole purpose. Fechner’s law and methods for psychophysical measurement have been used by scientists studying psychology ever since the publication of Elemente der Psychophysik (Robinson, n.d). Even to this day, Fechner’s importance and influence can be seen in most psychological work.

Contemporary assessments on Gustav Fechner

Fechner had a large contemporary impact on psychology. His work and influence can be seen throughout psychology; however, it can be argued that his influence is far more methodological than theoretical, as most works tend to be from other historical psychologists. This made finding contemporary assessments on his work incredibly difficult. Although much research was conducted on the psychologist, finding notable, and relevant articles throughout the databases we learned about in class and also through additional databases posted on Waterloo’s Library website was unsuccessful. Two appointments were made with one of the librarian liaisons, (library assistant) who specializes in psychology. The librarian attempted to go through the databases in the similar ways tested before, albeit far more efficiently and extensively. Although again no major articles to reference were found. Despite little to no success, an abundant amount was learned about navigating the databases and also how to sign out books which in regards to this assignment included, Life After Death, written by Fechner. Unfortunately, the book, although seeming quite promising, was of no help.

Assessment aside, Fechner’s work definitely had a large impact on the psychology community. Although not overtly discussed, fechner’s work with the Weber-Fechner law, quantifying perceived change in stimuli compared to the actual mathematical representation of said change, is likely his most commonly used psychological contribution. The law is still used today as a common source of data and as frequently been used to support theories. The law has been questioned and debated by many psychologists overtime. In a rather recent article, published by Elsevier Science, (The neural basis of the Weber-Fechner Law: a logarithmic mental number line - 2003) uses studies based on number neurons to contradict the linear calculations of relative stimuli that uphold the Weber fechner law. The article declares that the calculations are more accurate when done logarithmically rather than linearly as Weber had suggested. This criticism of weber’s theory actually supports fechner’s interpretation of the law.

Some of his other large contributions are methods of constant stimuli, methods of bisection and related psychophysical tools.

Intro to the Life and Work of Fechner: Video

Below you will find a 4 minute video; including important details regarding Fechner’s life and work. Is is aided by visuals, and a concise summary voiced as an addition to better your understanding


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Read, J. C. A. (2015). The place of human psychophysics in modern neuroscience. Neuroscience, 296, 116–129.