Human computation refers to various ways in whcuh humans are used as part of computer calculations. This may include paid labour to translate portions of text that AI cannot interpret, or crowdsoursing using volunteers or those engaged in apparently unrelated tasks. One of the earliest examples of human computation, was the use of reCAPTCHA, a form of 'verify you are human' technique to fill in gaps in OCR of old dicuments. Human computation is related to human-in-the-loop technqiues, and the two terms may be used interchangably, however 'human-in-the-loop' tends to refer to situations where the human is taking active and accountable control of ultimate decison making, whereas 'human compution' has connotations of the human used as a cog in the machine.
Defined on page 414
Used on Chap. 10: page 211; Chap. 17: page 414
Links:
doi.org: 
Early reCAPTCHA -- human as gap filling for automated systems
Publicity photo of Charlie Chaplin for the film Modern Times (1936). (source: United Artists, Public domain, via Wikimedia Commons)
