[3] In the more general use of the word, a causal relationship between the phenomena is implied;[1][2] the epiphenomenon is a consequence of the primary phenomenon.
Although electronics is said to be due to the influence of electrons, the standard approach to the study of electrical phenomena due to James Clerk Maxwell views these particles as secondary: In Maxwell's theory, charge and current are 'epiphenomena' (secondary appearances) of underlying processes in what he termed, following Faraday, the electric and magnetic fields.
Indeed, Maxwell's mature theory stays completely away from microstructure of matter and from any consideration of ‘electric substance’.
These quantities (the fields) may depend on microphysical events, and indeed Maxwell did expend some effort in his early papers on attempting to explain qualitatively how their relations could result in mechanical motions.
However, the theory explains only large-scale phenomena, and it is not necessary to have the microscopic model in mind in order to work successfully with it.
[4]Zenon Pylyshyn suggested a propositional model of cognition where people do not conceptualize ideas in images but rather in meaningful relationships.
In this theory, epiphenomena refer to images because they are merely products people conceptualize from their actual thought processes.