While I wish I knew a name for the entire field you describe "strong human-computable encryption schemes", here are some names I've encountered for various sub-fields:

• steganography: Modern steganography schemes are designed to be resistant to highly automated computerized attack. A few are designed to be encoded and decoded by humans -- for example, Richard Bergmair and Stefan Katzenbeisser: "Content-Aware Steganography: About Lazy Prisoners and Narrow-Minded Wardens" 2005.
• CAPTCHA, aka human interaction proof: systems designed to be resistant to highly automated computerized guessing attacks. (CAPTCHA)
• mental cryptography: mental-poker
• pen-and-paper cryptography: pen-and-paper
• encryption without suspicious tools: a hand-held 4-function calculator, decks of playing cards (Solitaire), pencil, paper, a dictionary/book/magazine/newspaper (but excluding nomenclator codebooks) for use in a running key cipher or a book cipher, etc.
• nomenclators : my understanding is that some historical encrypted messages composed using codebook ciphers have resisted even computerized attempts at decryption.
• purely mechanical cryptography: the humans enciphering and deciphering are allowed complicated mechanical machines (for example, Pinwheel machines, aka Pin-and-lug cipher machines ), but this category excludes machines powered by electricity.
• visual cryptography: an implementation of one-time pad encryption that allows humans to decode the message remarkably quickly. Later variants implement k of n secret sharing. ( "Visual Cryptography is the Coolest Thing Ever" )

While I wish I knew a name for the entire field you describe "strong human-computable encryption schemes", here are some names I've encountered for various sub-fields:

• steganography: Modern steganography schemes are designed to be resistant to highly automated computerized attack. A few are designed to be encoded and decoded by humans -- for example, Richard Bergmair and Stefan Katzenbeisser: "Content-Aware Steganography: About Lazy Prisoners and Narrow-Minded Wardens" 2005.
• CAPTCHA, aka human interaction proof: systems designed to be resistant to highly automated computerized guessing attacks. (CAPTCHA)
• mental cryptography: mental-poker
• pen-and-paper cryptography: pen-and-paper
• encryption without suspicious tools: a hand-held 4-function calculator, decks of playing cards (Solitaire), pencil, paper, a dictionary/book/magazine/newspaper (but excluding nomenclator codebooks) for use in a running key cipher or a book cipher, etc.
• nomenclators : my understanding is that some historical encrypted messages composed using codebook ciphers have resisted even computerized attempts at decryption.
• purely mechanical cryptography: the humans enciphering and deciphering are allowed complicated mechanical machines (for example, Pinwheel machines, aka Pin-and-lug cipher machines ), but this category excludes machines powered by electricity.
• visual cryptography: an implementation of one-time pad encryption that allows humans to decode the message remarkably quickly. Later variants implement k of n secret sharing. ( "Visual Cryptography is the Coolest Thing Ever" )

While I wish I knew a name for the entire field you describe "strong human-computable encryption schemes", here are some names I've encountered for various sub-fields:

• steganography: Modern steganography schemes are designed to be resistant to highly automated computerized attack. A few are designed to be encoded and decoded by humans -- for example, Richard Bergmair and Stefan Katzenbeisser: "Content-Aware Steganography: About Lazy Prisoners and Narrow-Minded Wardens" 2005.
• CAPTCHA, aka human interaction proof: systems designed to be resistant to highly automated computerized guessing attacks. (CAPTCHA)
• mental cryptography: mental-poker
• pen-and-paper cryptography: pen-and-paper
• encryption without suspicious tools: a hand-held 4-function calculator, decks of playing cards (Solitaire), pencil, paper, a dictionary/book/magazine/newspaper (but excluding nomenclator codebooks) for use in a running key cipher or a book cipher, etc.
• nomenclators : my understanding is that some historical encrypted messages composed using codebook ciphers have resisted even computerized attempts at decryption.
• purely mechanical cryptography: the humans enciphering and deciphering are allowed complicated mechanical machines (for example, Pinwheel machines, aka Pin-and-lug cipher machines ), but this category excludes machines powered by electricity.

While I wish I knew a name for the entire field you describe "strong human-computable encryption schemes", here are some names I've encountered for various sub-fields:

• steganography: Modern steganography schemes are designed to be resistant to highly automated computerized attack. A few are designed to be encoded and decoded by humans -- for example, Richard Bergmair and Stefan Katzenbeisser: "Content-Aware Steganography: About Lazy Prisoners and Narrow-Minded Wardens" 2005.
• CAPTCHA, aka human interaction proof: systems designed to be resistant to highly automated computerized guessing attacks. (CAPTCHA)
• mental cryptography: mental-poker
• pen-and-paper cryptography: pen-and-paper
• encryption without suspicious tools: a hand-held 4-function calculator, decks of playing cards (Solitaire), pencil, paper, a dictionary/book/magazine/newspaper (but excluding nomenclator codebooks) for use in a running key cipher or a book cipher, etc.
• nomenclators : my understanding is that some historical encrypted messages composed using codebook ciphers have resisted even computerized attempts at decryption.
• purely mechanical cryptography: the humans enciphering and deciphering are allowed complicated mechanical machines (for example, Pinwheel machines, aka Pin-and-lug cipher machines ), but this category excludes machines powered by electricity.
• visual cryptography: an implementation of one-time pad encryption that allows humans to decode the message remarkably quickly. Later variants implement k of n secret sharing. ( "Visual Cryptography is the Coolest Thing Ever" )