Electromagnetic energy leads to

which leads to the primary visual cortex, therefore giving

Chemical composition leads to

which leads to the gustatory cortex which results in

Chemical compositions lead to

which leads to the offactory cortex, resulting in

Air pressure waves leads to

which leads to the auditory cortex, resulting in

Tissue distortion leads to

and

which leads to the somatosensory cortex, resulting in

Gravity acceleration leads to

which leads to the temporal cortex, resulting in

In 'normal' multi-sensory perception two different things, (features, senses, symbols) become bound together.

In synaesthesia, a single thing (a perceptual feature, symbol etc) becomes bound together with a perceptual experience that is illusory in nature.

Individuals presented with sensory input in one modality consistently and automatically experience a sensory event in a different modality.

Concrete perceptual experiences (not

). Elicited by stimuli in the external environment or by internal thoughts (not

). Automatic and cannot be suppressed (unlike thinking and

).