Psychology Laboratory

Philosophy, science and psychology

David Hume was an empiricist. That means that he thought that the only source of knowledge is via the senses.

Consider two accounts of an empirical observation:

    Sarah walked towards the light switch, pushed it down and caused the light to come on.

    The light drew Sarah to the switch, pulled her finger onto it and forced it down.

How do we know from what we see that Sarah causes the light to go on and that the light did not cause Sarah to push the switch down? You will probably say that the light went on after Sarah walked towards the switch and pushed it down. If so, it means that you believe causes precede effects. But is that something you see? Try to imagine the future as a gigantic vacuum cleaner sucking effects towards it. If that was the case the cause would be after the effect, but would what you see in the world be any different?

In order to see Sarah cause the light to come on we have to have a model of time and space in our minds in which movements can only be causes if they precede the movements that we perceive as effects. It seems that only part of what we see is "out there", the other part is already in our heads, organizing the sensations that we receive from the external world.

Immanuel Kant called the principles by which our minds organize the world "categories".

The categories include such concepts as time, space, causality and number. The world we know, he argued, is the world as organized by our own categories. He called this the "phenomenal" world. The external or "noumenal" world is hypothesized about - but it can never be known directly. There is a major exception to this last statement. The world of "practical reason" (morality) is known directly. But for this discussion we do not need to consider Kantian ethics.

Elsewhere, we have now come across two distinct views about how the mind works. You could consider these as "research programmes" - general theories about the world that suggest different questions that you can ask it - or you can consider them as rival hypotheses that need in some way to be tested.

According to the first view, the content of our mind is basically a reflection of external reality. This is, however, liable to be distorted by our fantasies. The search for truth is, therefore, an attempt to separate fantasies from observations.

This is the tradition that stems from Hobbes and Locke. Lock maintained that the mind of a new born baby is a blank sheet waiting for sensations to write ideas on it from the outside world. The British "associationists" - notably David Hartley, who died in 1757, Hume and the two Mills (James and John Stuart) - argued that even our most complicated ideas come from the association of simple ones that are derived from direct perception of the external world. Kant, on the other hand, argued that the mind itself contributes so much to its own perceptions that we cannot even know the noumenal world behind perception. We are restricted to knowledge of the phenomenal world that results from our minds organizing the data of sensation. Science

The important question for this discussion is this: Are disagreements about how our minds work investigated best by philosophy (by argument) or is there a "scientific" method of examining them which is better?

John Stuart Mill argued in his Logic (1843) that psychology (the study of mind) could become a science of experiment and observation. But for his part he continued to argue philosophically. He developed the theory that when ideas are associated in our minds they behave like elements in a chemical reaction. Two simple ideas brought together, therefore, create something new.

British associationists, like the Mills, were read in the universities of Germany - by people used to the ideas of Kant - and it was at Leipzig (now in East Germany) that the first experimental psychology laboratory was set up by Wilhelm Wundt in 1879.

To understand why this was the first psychology laboratory you must distinguish psychology, the study of mind, from physiology, the study of the body - even though physiology includes the study of the brain.

Wundt was, for many years, the assistant to Herman Helmholtz. Helmholtz was a physiologist. In Pioneers of Psychology Raymond Fancher shows how Helmholtz's experiments on how the eye sees things seem to support Kant's contention that we structure our perceptions (l). Helmholtz wrote:

"That the character of our perceptions is conditioned just as much by the nature of our senses as by the external of the greatest importance for the theory of our faculty of perception. What the physiology of the senses has demonstrated experimentally in more recent times, Kant earlier tried to do...for the ideas of the human mind in general." ((quoted Fancher, R.E. 1979 p.110)

To become psychology the experimental method had to move from the study of nerves to the study of consciousness. Later psychologists (the behaviourists) were to argue that psychology should ignore consciousness and study behaviour. But this was not how the nineteenth century psychologists saw it.

In 1867 William James wrote to a friend:

"It seems to me that perhaps the time has come for psychology to begin to be a science - some measurements have already been made in the region lying between the physical changes in the nerves and the appearance of consciousness (in the shape of sense perceptions), and more may come of it..¨Helmholtz and a man named Wundt at Heidelberg are working at it..." (quoted Fancher, R.E. 1979 pp 132-133)

Those of you who read Frankenstein will remember the professors of chemistry in a German university exploring the basis of life. Here are their real life counterparts wondering if they can get mind as well as matter into a test- tube!

The established way to study the mind was "introspection" - looking in on your own mind. Can we, Wundt wondered, make this part of a laboratory experiment? The following model of a Wundtian experiment can be carried out in a seminar with a stop watch. It does not really work with the second hand of an ordinary watch - but if that is all you have it can still be amusing to try it. The experiment combines information derived from the physiological study of the nervous system with introspection and "behavioural observations.

  1. In the first part of the experiment we are going to measure the speed at which a sensory message travels along the longest nerve in a student's body. This runs from the foot to the top if the thigh. The student volunteer (Fred) should stand up with his back to another student (Jane) who is to give sensory messages to the nerve by touching the back of his leg.

  2. To demonstrate the method, Jane touches the back of Fred's leg just behind his ankle and when he feels the touch Fred should raise his arm. A third student measures the time between Jane's touch and Fred's arm raising.

  3. What does this time represent? Helmholtz reasoned that it is partly the time that the message takes travelling along the nerves, but that this is complicated by the time the subject (Fred in our case) spends thinking about it. How can we cut out the thinking time? The way to do this is to take two time measurements and subtract one from the other. The first measurement we have already taken. The second one is made by Jane touching the top of Fred's leg. The time that is left over when we take this shorter time from the previous longer time should be the time it took for the message to travel from the bottom of the leg to the top. In other words, we have cut out consciousness.

  4. Wundt argued that if we can cut out consciousness we can put it back. For the third (and final) part of the experiment Fred is to think of different things whilst Jane touches the back of his leg in the same spot. First he can focus on the expected touch from Jane, then he can focus on the response he intend to make (raising his hand). According to Wundt the response when he is focusing on raising his hand will be about one-tenth of a second faster than when he is focusing on the expected touch.

In this, and many other experiments, Wundt believed that he was beginning to study consciousness scientifically.

But there are levels of consciousness that Wundt believed are beyond experimental examination. Human thought, memory and understanding, he argued, take place in the context of established cultures and history. We could set up an experiment to study people's responses to walls falling down, for example, but what would that tell us about the response of Berliners to their wall coming down?

Wundt argued that there are three levels at which we need to analyse mind in order to understand it. In my words these are: the physiological, the psychological and the sociological. Wundt called the third one "folk- psychology". Wundt's contention that experimental psychology is unable to analyse culture was one of the cues that led Durkheim to found sociology as a separate science.

Study links outside this site
Picture introduction to this site
Andrew Roberts' web Study Guide
Top of Page Take a Break - Read a Poem
Click coloured words to go where you want

Andrew Roberts likes to hear from users:
To contact him, please use the Communication Form

home page for social
science home page to Andrew Roberts'
web site ABC Study Guide index

Time Line links

ABC of Experiments


David Hume

Immanuel Kant

John Stuart Mill

Wilhelm Wundt