This museum traces the history of reaction time research. It is a subdivision of the MUSEUM OF THE HISTORY OF PSYCHOLOGICAL INSTRUMENTATION which includes many downloadable descriptions and pictures of the wide variety of instruments used by early psychologists in their task of studying the mind and behavior.
Starting with descriptions and pictures from an early German catalog
of psychological and physiological apparatus, the main museum is growing by
developing historical threads that trace the development of knowledge in
the major areas of psychological inquiry and which show the apparatus associated
with each area. We feel that it is appropriate that the first such thread
traces the first truly scientific experiments in psychology which were
designed to provide accurate and reproduceable measurements of mental processes.
(Much of the information in this historical thread comes from a paper entitled: 'The Calibration of Minds and Machines in Late 19th Century Psychology' by Ruth Benschop and Douwe Draaisma of the Department of History and Theory of Psychology at the University of Groningen, Grote Kruisstraat 2/1, 9736 BW Groningen The Netherlands.)
Interest in the measurement of human reaction time (the time elapsing between the onset of a stimulus and the onset of a response to that stimulus) apparently began as a result of the work of a Dutch physiologist named F. C. Donders. Beginning in 1865, Donders became interested in the question of whether the time taken to perform basic mental processes could be measured. Until that time, mental processes had been thought to be too fast to be measurable.
In his early experiments, Donders applied electric shocks to the right and left feet of his subjects. The subject's task was to respond by pressing a telegraph key with his right or left hand to indicate whether his right or left foot had received the shock. In one experimental condition the subject knew 'in advance' which foot was to receive the electric shock and in the other condition the subject did not know 'in advance' which foot was to receive the shock. Donders found that the difference between the two conditions was 1/15 second. This measurement represented the very first time that the human mind had been measured. Donders was apparantly aware of the importance of his discovery because he wrote: "This was the first determination of the duration of a well-defined mental process. It concerned the decision in a choice and an action of the will in response to that decision."
Donders' ability to accurately measure such a short time interval was greatly facilitated by the solution of an earlier military problem. In 1840, the Englishman Charles Wheatstone invented a device for measuring the velocity of artillery shells. The device, which was based on his early electric telegraph system, was started electrically when the projectile left the muzzle of a gun and stopped electrically when it struck the target.
By 1842, a Swiss watchmaker named Mathias Hipp had improved on Wheatstone's design and began selling an instrument which used a tuning fork-like spring which vibrated at 500 Hz to repetitively engage the teeth of a wheel and thus regulate the speed of revolution of the wheel. Later models of his 'Hipp Chronoscope' had vibrating regulators which vibrated at 1000 Hz. This improved their accuracy.
The clockwork mechanism of the Hipp Chronoscope was caused to rotate
continuously by a motor powered by a heavy weight. At the start of a reaction-time
measuring trial, the mechanism was set in motion but prevented from moving
the indicating hands on its dial by a clutch which was held in the disengaged
position by an electrically-energized solenoid. When the electrical current
through the solenoid was interrupted, the clutch engaged and the dial rotated
rapidly. When the current was reestablished, the clutch disengaged and
the dial stopped at a reading which showed the elapsed time in thousandths
of a second.
An example of a Hipp Chronoscope from
The Barnard College Psychology Department History of Psychology Collection.
Although Donders did not continue to pursue his interest in the reaction time, Willhelm Wundt built an elaborate laboratory and research program around measuring the time taken by various mental processes. A student of the eminent and meticulous researchers, Hermann von Helmholtz and Emil Du Bois-Reymond, Wundt designed a psychology laboratory in Leipzig which was to become the model for dozens of scientific psychology laboratories throughout the world. His focus on the precise measurement of psychological processes or "MENTAL CHRONOMETRY" became the central issue in psychological research from the 1870's certainly into the 1950's. His insistence on precision of measurement has continued to influence the design of psychological experiments to the present.
Although the date 1879 is often given as the date of establishment of Wundt's first laboratory in Leipzig, it is clear that he was busy designing and performing precise measurements of human reaction times far earlier. His book: 'Grundzuge der physiologischen Psychologie' appeared in 1873 and contained a great deal of information about this new kind of psychological research.
The Hipp Chronoscope was unfortunately prone to a number of serious problems which tended to produce inaccurate readings. Such inaccuracies were unacceptable to well trained students of Helmholtz such as Wundt and great efforts were expended in his laboratory to study the source of these errors and to correct them.
One major problem was that the vibrating spring escapement would, at unpredictable times begin to vibrate an octave lower at half its usual speed. This shift in vibration speed was often audible to the experimenter who would discard the data from that reaction time trial but the problem persisted and no solution was ever found. Experimenters simply had to listen closely to the pitch of the tone made by the machine and be ready to discard trials when the tone changed.
Another problem was caused by the time it took for the electric current to release and pull-in the solenoid which operated the clutch. The RELEASE TIME was highly dependent on the applied voltage. Low voltages allowed the mechanism to release immediately as soon as the voltage was removed from the coil. Higher voltages induced stronger magnetic fields into the core of the coil which took longer to decay after the voltage was removed and which held the clutch disengaged for a longer time after the voltage was removed. The PULL-IN TIME was also highly dependent on the applied voltage. Low voltages pulled in the mechanism slowly due to the fact that they built up sufficient magnetic flux to operate the clutch slowly. High voltages pulled in the mechanism rapidly due to the fact that they built up magnetic flux rapidly. To help with this problem, the Hipp Chronoscope was always used in conjunction with a voltmeter which helped to assure that the same voltage was being applied to the coils on every trial.
However, since 'wet' chemical batteries were used, the amount of current that they could provide varied throughout the day as did their voltage and this led to considerable variability in the measurements.
These problems were percieved as major obstacles to the development of a precise 'science' of psychology as the developing field of psychology struggled to portray itself as a science with a rigorous scientific method on a par with that of the natural sciences.
Another device was invented to act as a calibration standard for the Hipp Chronoscope. It was designed to produce an absolutely accurate interval of time between opening its electrical contacts and closing them. It was called the 'CONTROL HAMMER' and it was quite literally a falling hammer-like weight which opened and closed electrical contacts as it fell by them. An electromagnet released the hammer and it fell past one electrical contact which opened the circuit to the Hipp Chronoscope, engaging its clutch and starting it measuring time. When the hammer fell past a second electrical contact, the circuit was closed. This disengaged the clutch on the Hipp Chronoscope and stopped its dial from moving. The 'control hammer' was supposed to provide an absolutely reliable time interval which could be used to calibrate and check on the operation of the Hipp Chronoscope.
Unfortunately, the control hammer itself needed to be calibrated. In order to know exactly how long the 'constant' interval provided by the control hammer was, another device which could accurately measure extremely small time intervals was needed. This device was the 'chronograph'.
The chronograph consisted of a rotating cylinder covered with a soot-smoked piece of paper. The black soot on the paper allowed a beard-hair to leave a mark on the paper as the cylinder rotated. The beard hair was glued to a tuning fork which vibrated at exactly 1000 Hz (vibrations-per-second). Thus, a wavy line was drawn on the smoked paper with each wave indicating the passage of 1 millisecond (1/1000 second).
Lightweight electrical solenoids put other marks on the paper when the clutch of the Hipp Chronoscope was engaged and disengaged by the control hammer apparatus and the number of waves on the paper which separated these marks indicated the time duration in milliseconds.
The chronograph, then, calibrated the control hammer which calibrated the Hipp Chronoscope which measured the reaction times of the subject.
Although a significant portion of each day was spent in laboriously calibrating the Hipp Chronoscopes, Wundt gradually collected measurements of a wide variety of mental phenomena.
Additional threads tracing the history of other types of psychological research will be added shortly !
Return to the MUSEUM OF THE HISTORY OF PSYCHOLOGICAL INSTRUMENTATION.
The
Barnard College Psychology Department History of Psychology Collection.
This on-line internet museum contains lots of photographs and descriptions
of early psychological research apparatus.
CONTACTS:
Thomas B. Perera Ph. D.
Professor Emeritus of Psychology
Department of Psychology
Montclair State University
NOTE: Dr. Haupt died of cancer in February, 2001.
Edward J. Haupt Ph. D.
Professor of Psychology Department of Psychology
Montclair State University
Upper Montclair, NJ 07043