A Human Intelligence Task, or HIT, is a question your application asks, and a Worker answers. Your application submits a HIT using the CreateHIT operation.
A HIT includes:
You can tag a HIT with a RequesterAnnotation, a value visible only to you. You can use this value to associate the HIT data with an identifier internal to your application.
Once created, the HIT becomes browsable and searchable on the Mechanical Turk web site, and can be accepted and completed by a Worker whose Qualifications match the HIT's Qualification requirements. Searching HITs matches search terms again the Title, Description, and Keywords fields.
In most cases, you will want to ask many questions of the same kind, such as identifying an object in each of thousands of photos. Mechanical Turk groups similar HITs together, and Workers search and browse the groups while looking for work. If a Worker qualifies for HITs in the group, the Worker may preview a single HIT, then accept it and begin work. When a Worker completes one HIT in a group, the Worker is encouraged to complete another in the same group. Most Workers will complete many similar HITs in a single session.
Two HITs appear in the same group if every field contains identical data, with a few exceptions. HITs in the same group may have different values for the following fields:
All other fields, including the title, the description, and the reward, must have identical values for HITs to be considered to be in the same group.
A HIT can have a Reward, an amount of money paid to the Worker once you approve the results the Worker submitted. This amount is transferred from your account to the Worker's account automatically once the results are approved.
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A HIT can have a reward of zero dollars, if you like. Remember that a minimum HIT listing fee will still apply, even if the reward is zero.The Question field of a HIT describes what is being asked of the Worker. It includes any information required to answer the question, such as text or images, as well as a description of the range possible answers.
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The Mechanical Turk Service passes questions and answers between your Requester application and Workers. Workers read questions and provide answers using the Mechanical Turk web site. The format of this data is device-independent, so future Worker interfaces to Mechanical Turk can be built on platforms with varying capabilities.
Be aware that the Worker interface is not guaranteed to display your questions in a particular way, nor is it guaranteed to return answers within the ranges you specify in the question form. Mechanical Turk only ensures that the question and answer data conform to the appropriate schemas.
The question form specification may include multiple fields, or "questions." A question can have the Worker select zero, one or more options from a list (true/false, multiple choice), or it can have the Worker type in text or a number.
The question form specification may suggest the style of a field, guiding how a question may appear to the Worker. Multiple choice questions may appear as radio buttons, checkboxes, or a dropdown list, among others. The suggested style is not guaranteed, since Mechanical Turk may adjust the appearance to fit the device the Worker is using to see the question.
The specification may also suggest ranges of possible answers for the question. It is up to the device presenting the question to the Worker to validate the Worker's answers, so the results in the assignment are not guaranteed to meet these criteria. Your application should always validate the answers it receives.
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For more information about the question and answer specification format, see the QuestionForm data structure.