# Human Computation (11/2/2016)

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

A concrete model for human computation will allow us to:

1. Estimate human usability
2. Count steps and prove human usability mathematically
3. Assert that certain things are impossible for human computation

# Humans vs. Computers

1. Computers are faster in doing arithmetic operations.
2. Computers keep improving in speed and memory.
3. When counting steps, hidden constants are crucial (i.e. O(n) may not be good enough for humans if hidden constant c is large).
4. 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:

1. 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
2. Short term or working memory (STM):
• Easy to read and write
• Tiny in size: $7 \pm 2$ chunks
• Storage is fleeting: items in STM are pushed out by new deposits
• Chunks are “pointers” into memory

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