Mechanical Turk Concepts

This summarizes some basic concepts for those who are not already familar with Mechanical Turk.


A HIT type is a group of tasks (HITs). All HITs in a HIT type have the same title, description, reward, keywords, time limit, qualification requirements, and auto-pay delay. Each item on the main menu represents one HIT type.


A HIT is a single task within a HIT type. Each HIT type may contain ≥1 HITs.

An assignment is the result of a single worker doing a single HIT. Each HIT may result in ≥0 assignments.

When creating a HIT, you specify the max assignments, number of judgments (assignment) you are requesting. There is no guarantee you will get that many, but you won’t get any more.

You must approve (choose to pay) or reject (refuse to pay) each assignment. If you do not approve or reject an assignment within the auto-pay delay that you specified with the HIT type, it will be automatically approved.

A question corresponds to a single HTML input element in the HIT interface. Each HIT consists of ≥1 questions.

An answer is a response to a single question. Each assignment consists of ≥1 answers.


Restricting access to HITs

A qualification type is a test or other measure used to restrict which workers may access certain HIT types. Examples:

  • geographic location
  • approval rate on past work
  • score on custom screening test created by you
  • is adult?

A qualification requirement is the threshold workers must meet to work on a given HIT type. Examples:

  • geographic location must be USA
  • approval rate on past work must be ≥90%
  • score on custom screening test created by you must be ≥8
  • worker must be an adult

A qualification is the credential that allows a worker to access restricted HITs. Examples:

  • worker W12345678’s geographic location = USA
  • worker W12345678’s approval rate on past work = 93%
  • worker W12345678’s score custom screening test created by you = 9
  • worker W12345678 is an adult