By the end of the 19th centuryÉ..
q Different sensations (pain, touch,
smell, sight, hearing)
are mediated by different
physiological structures
in the nervous system
q Within a modality (e.g. sight)
different nerve fibres respond
selectively to different stimuli (e.g. different ranges of
wavelength)
q
Perception is affected by in-built knowledge of the world, i.e.
is not a simple transformation of the raw sensory input