[mrsharpoblunto]

Makes me wonder if you could effectively apply Chernoff faces (https://en.wikipedia.org/wiki/Chernoff_face) to make different hashes easier for humans to recognize. TLDR map parts of the hash to modify aspects of a face (position, size, orientation of eyes, ears etc.) and you can take advantage of all the in-built circuitry in the human brain which can identify very small differences in facial appearance.

The idea is explored a bit in Peter Watts novel Blindsight - not for hashes, but visualizing high dimensional multivariate data via clouds of tormented faces :)