Page 15 - History of Psychology

Ernst Heinrich Weber (1795–1878), was the first to attempt to measure the
relationship between a physical stimulus and the sensation it evokes. He

determined two-point thresholds for different parts of the body by observing the
smallest distance between two points of stimulation that would be reported as
two points. Working with weights, Weber determines how much or less a standard
weight is before it is reported as different from the standard. This sensation of
difference is called real difference (jnd).

Gustav Theodor Fechner (1801–1887), expanded on Weber's work by showing that
jnds is related to stimulation geometrically. That is, as the magnitude of the
standard stimulus increases, so does the amount that needs to be added to or
subtracted from the comparison stimulus before the difference can be noticed. In
addition to psychophysics, Fechner also created the field of experimental
aesthetics. Now that it had been shown that mental events could be studied
experimentally, the groundwork was laid for the establishment of psychology as
an experimental science.

Fechner uses several methods to further explore the mind-body relationship:
1. Boundary method: With this method, one stimulus is varied and compared
with a standard. To begin with, the variable stimulus can be equal to the
standard and then vary, or it can be much stronger or weaker than the
standard. The aim here is to determine the range of stimuli that the subject
considers to be equal to the standard.
2. Constant stimulation method: Here, pairs of stimuli are presented to the
subject. One member of the pair is standard and remains the same, and the
other varies in magnitude from presentation to presentation. Subjects
reported whether the stimulus variable appeared greater than, less than, or
equal to the standard.
3. Adjustment method: Here, the subject has control over the variable stimulus
and is instructed to adjust its magnitude so that the stimulus that appears is
the same as the standard stimulus. After adjustment, the mean difference
between the variable stimulus and the standard stimulus was measured.

Discussion Questions

What significance did Weber's work have for the development of experimental
psychology?
Summarize Fechner's psychophysical work and methods and what were
Fechner's contributions to the development of psychology as a science!

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