The History of
Colour Vision Science
Early philosophers and scientists held very different views
regarding vision and colour perception than those now accepted in
contemporary vision science. In this component of the Bases of
Colour Vision, we will explore some of those views.
Views of the Early
Reflecting the zeitgeist
of the age, the early Greek philosophers of Hellenic times escaped
the use of experiments to explain the experience of colour.
This non-empirical speculative approach is reflected in the following
statement by Plato (429-347 BCE)
regarding colour vision.
"The law of proportion according to which the several
colours are formed, even if a man knew he would be foolish in telling,
for he could not give any necessary reason, nor indeed any tolerable
or probable explanation of them. "
- Plato, Timaeus 68
Plato's statement reflects one of the most enduring problems in the
history of colour vision science - the dependence on assumption over
In the fifth century BCE, Empedocles (493-433 BCE) wrote that the
eye functioned like a lantern, that light from the eye shining outwards
would interact with the "outer rays" and thereby allow objects
to be seen. This concept was later refined by Plato in his emanation
Aristotle (384-322 BCE), Plato's devoted pupil, propagated a different
notion of colour vision. He thought that colour was based on the interaction
of stimulus brightness and ambient light level. He based this view
on the perception that the colour of a sunset changed as darkness
The Middle Ages (5th c. - 15th
Ravaged by plagues, poverty, and
religious wars, Europe did little to advance the cause of science
or our understanding of colour vision during the Middle Ages. Many
thought God would not approve of such tinkering with His creation.
Arab scholar Alhazen (965-1069 CE) proposed a camera obscura
model for the transmission of light in the eye, but did not speculate
on the basis of colour vision.
The Foundations of the Trichromatic
seventeenth century marked the beginning of the Enlightenment in Europe,
an era characterized by the emergence of self-declared "scientists."
Pre-eminent among them was the universal genius, Sir Isaac Newton
Newton escaped the confusion between the proximal and distal stimulus
by experimentation. He is famous for his experimental demonstration
that a prism could refract a narrow beam of sunlight into all the
colours of the rainbow. He also showed that the colours that compose
white light could not be further subdivided, but they could be recombined
to form white light. His conclusion was that colour is not the product
of the external objects we see, but is a property of the eye itself.
This provided the foundation for modern theories of colour vision.
his interests and contributions to colour vision, Newton did not concern
himself with proving his theories on colour perception.
The scientific notion that colour vision is explained by the action
and interaction of three different "particles" (cf. Newton,
Palmer, Young, Helmholtz) was not actually proven until the twentieth
century when modern scientific techniques permitted the discovery of
three different cone photopigments. Early attempts at
"trivariance theory" proper was only one among
George Palmer (ca. 1786) was one of the first to put forward
the notion that colour vision is based on the "maximal sensitivity"
of retinal "particles." Palmer is not usually given deserved
recognition for this original idea; credit for this important idea
is often erroneously given to Thomas Young.
Young (1773-1829) argued that there was a limited rather than infinite
number of different retinal "particles" at every point on
the retina to respond to light. He suggested that there might be three
such particles only, a view later validated by science. His key contribution
to colour vision science may have been to restate Palmer's concept
of spectral sensitivity.
von Helmholtz (1821-1894) championed Young's idea that retinal particles
varied in the light to which they were "maximally sensitive."
As a result, the trichromatic theory of colour vision also came to
be known as Young-Helmholtz Theory. Influenced by his colour mixing
experiments, however, Helmholtz could not accept the notion that there
could be fewer than five colour primaries. Thus, he failed to accept
the three retinal primaries proposed by Young.
A contemporary of Helmholtz, physicist James Clerk Maxwell (1831-1879),
suggested that any physically pure primary is bound to be subjectively
complex due to the complexity of the underlying processes. He held
that the eye creates colour, and the observation of colour taints
the experiment itself. In this Maxwell broke free of the last remnants
of naive realism. His was the last major contribution of the nineteenth
century to spectral sensitivity.
Ewald Hering and the Opponent
Ewald Hering (1834-1918) observed that the "trichromatic theory"
could not explain the phenomenon of afterimages, negative-coloured
images seen after extended viewing of a coloured object (e.g.,
red after green, or yellow after blue). Hering based his work
on the subjective appearance of colours, and wondered why certain
colours could never be seen or even described, such as bluish-yellow
Hering proposed that the visual system
generated signals in opposing pairs (i.e., yellow-blue, red-green,
white-black). However, it was not until much later in the twentieth
century that neural experiments proved him correct. At the time his
theory was seen by many to compete with the trichromatic theory. Hering
himself held that both theories could be equally valid. We now know
that he was correct - the two theories simply reflect processes at
different levels of visual processing.