1904 in psychology, "a conception of oneself" in relation to others; see self- + image (n.).
Entries linking to self-image
self-
word forming element indicating "oneself," also "automatic," from Old English use of self (pron.) in compounds, such as selfbana "suicide," selflice "self-love, pride, vanity, egotism," selfwill "free will." Middle English had self-witte "one's own knowledge and intelligence" (early 15c.).
OED counts 13 such compounds in Old English. Middle English Compendium lists four, counting the self-will group as a whole. It re-emerges as a living word-forming element mid-16c., "probably to a great extent by imitation or reminiscence of Greek compounds in (auto-)," and formed a great many words in the pamphlet disputes of the 17c.
image n.
c. 1200, "piece of statuary; artificial representation that looks like a person or thing," from Old French image "image, likeness; figure, drawing, portrait; reflection; statue," earlier imagene (11c.), from Latin imaginem (nominative imago) "copy, imitation, likeness; statue, picture," also "phantom, ghost, apparition," figuratively "idea, appearance," from stem of imitari "to copy, imitate" (from PIE root *aim- "to copy").
Meaning "reflection in a mirror" is early 14c. The mental sense was in Latin, and appears in English late 14c. Sense of "public impression" is attested in isolated cases from 1908 but not in common use until its rise in the jargon of advertising and public relations, c. 1958.
To þe ymage of god he made hym [Genesis i.27, Wycliffite Bible, early version, 1382]