What is a reasonable model for human computation (without using a paper and pencil)?

A concrete model for human computation will allow us to:

- Estimate human usability
- Count steps and prove human usability mathematically
- Assert that certain things are impossible for human computation

# Humans vs. Computers

- Computers are faster in doing arithmetic operations.
- Computers keep improving in speed and memory.
- When counting steps, hidden constants are crucial (i.e. O(n) may not be good enough for humans if hidden constant c is large).
- Some problems become easy with respect to human computation. For example,
**factoring**is a hard problem in general. However, any number calculated by a human by multiplying two equal-length primes (in head) can be factored by a laptop within seconds.

Major Open Problem: Can humans compute 1-way functions (in their head) that powerful supercomputers cannot invert?

# Model of human conscious computation

Turing machine with two distinct tapes:

**Long term or permanent memory (LTM)**:- Hard to write (can only be written to slowly)
- Easy to read (can be read quickly)
- Retention requires rehearsal on Wozniak’s doubling schedule

**Short term or working memory (STM)**:- Easy to read and write
- Tiny in size: chunks
- Storage is fleeting: items in STM are pushed out by new deposits
- Chunks are “pointers” into memory

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