The extent that humans cluster objects below a certain size and of a similar purpose; the means of personalisation. Given that these are house keys and this is in the UK where breaking and entering is not uncommon – to what extent will the owner want to disguise which key belongs to which property? Move all this over into the digital domain where links are that much more apparent – how will the owner of the keys create sufficiently obscure references that mentally link the key with the corresponding key hole?

Related: personal cultural radar.