 In the subjective domain, data are conceived of as "sensory stimuli, which we perceive through our senses", or "signal readings", including "sensor and/or sensory readings of light, sound, smell, taste, and touch".Others have argued that what Zins calls subjective data actually count as a "signal" tier (as had Boulding), which precedes data in the DIKW chain.American information scientist Glynn Harmon defined data as "one or more kinds of energy waves or particles (light, heat, sound, force, electromagnetic) selected by a conscious organism or intelligent agent on the basis of a preexisting frame or inferential mechanism in the organism or agent."