Decryption that is easy for humans and hard/impossible for computers Is there any research into digital cyphers that are easy for humans to decrypt, but hard for computers?

One example is Captchas, though those are being increasingly broken by computers.  However, Captchas are not quite what I have in mind.  Captchas depend on human domain expertise, which could theoretically be captured algorithmically and then cracked pretty easily with computers.

What I am looking for are cyphers that humans can easily decrypt, but are provably computationally hard or impossible.  The encryption process has to also be performed algorithmically.

The scenario this encryption scheme would work in is the following:


The encrypted message is made available for offline processing.
Within a relatively short time the human can derive the message.
An algorithm will either find the message impossible to derive, or at least impossible in practice.
My opinion is that in order to design a cipher that is easier to decrypt by a human than by a competently programmed computer, the only working option is making the ciphertext or key unavailable to the computer due to some input limitation (like, the ciphertext or key is 3D-engraved in plexiglass, and the computer has no 3D vision); but that could be circumvented by an upgrade of the computer. With the relevant data available, no matter if we consider decryption with or without the key (the question is ambiguous about that), decryption is data processing, and properly programmed computers tend to vastly outperform humans at that.

Update: there are areas where the visual capabilities of the human brain (or possibly capabilities pertaining to other senses like audition) make humans somewhat competitive with computer programs; like finding a good move at the game of Go or Chess, an approximate solution to the Traveling Salesman Problem, or identifying some flaws in a pseudo random generator. I challenge that it allows constructing a cipher as asked, for two reasons:


For identification of flawed RNG, and arguably the TSP, there is evidence that humans perform significantly worse than computer programs primarily and competently designed for speed at the price of some error rate or non-optimality. Even for games, computer programs exist that beat the best humans with heavy hardware, and 99% of humans with a mere PC.
In tasks where humans are even mildly competitive with proper computer programs, humans tend to find only approximate solutions, and different humans will often find different solutions. It is hard to turn such capability into reliably deciphering a ciphertext, as necessary to answer the question.