Riders may synchronize their pedalling to be in time with the rhythm of the music, thus providing an external stimulus to encourage a certain tempo.

Each neuron in the network corresponds to one pixel in an input image, receiving its corresponding pixels color information (e.g. intensity) as an external stimulus.

Contenting oneself with reacting to an external stimulus means being unconscious of the act; an existence within the sheer presence of the body.

The ray regularly emits pulses even without an obvious external stimulus.

The game assumes that all external stimulus affects many aspects of our attitudes, personalities and even our health.