Amazon Mechanical Turk
API Reference (API Version 2012-03-25)
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CreateHIT

Description

The CreateHIT operation creates a new Human Intelligence Task (HIT). The new HIT is made available for Workers to find and accept on the Amazon Mechanical Turk website.

There are two ways to specify HIT properties when calling the CreateHIT operation: with the HIT type ID, or with the common property values. If the HITTypeId parameter is specified, the CreateHIT operation assumes the syntax with a HIT type ID is what you intended. If you provide both a HIT type ID and values for the common properties, the common property values are ignored.

CreateHIT also supports several ways to provide question data: by providing a value for the Question parameter that fully specifies the contents of the HIT, or by providing a HitLayoutId and associated HitLayoutParameters. If you are providing a data structure, it may be a QuestionForm structure, an ExternalQuestion structure, or an HTMLQuestion structure. For more information, see the Question parameter.

Using Review Policies with CreateHIT you can specify how you want Mechanical Turk to take action on the HITs you create. Using Review Policies removes the need for you to manually take action and determine Worker accuracy after the HIT has been completed. For more information about Review Policies, see Review Policies.

You must specify review policies when you create a HIT. You cannot apply a Review Policy to an existing HIT. There are two types of Review Policies, Assignment-level and HIT-level:

  • An Assignment-level Review Policy is applied as soon as a Worker submits an assignment. For more information, see Assignment Review Policies.

  • A HIT-level Review Policy is applied when a HIT becomes reviewable. For more information, see HIT Review Policies.

You can specify one Assignment-level Review Policy and one HIT-level Review Policy when you call CreateHIT using the HIT Review Policy data structure. The Assignment-level Review Policy ScoreMyKnownAnswer/2011-09-01 and the HIT-level Review Policy SimplePlurality/2011-09-01 can be used in the same call to CreateHIT.

  • Use the ScoreMyKnownAnswers/2011-09-01 policy parameters to compare a known answer you provide with the answer a Worker provides. Mechanical Turk will automatically compare the answer and take action based on your requirements.

  • Use the SimplePlurality/2011-09-01 policy parameters to automatically compare answers received from multiple workers and detect if there is a majority or consensus answer.

For more information about how to get the results you need from Workers, see Review Policy Use Cases.

Request Parameters

The CreateHIT operation accepts parameters common to all operations. Some common parameters are required. See Common Parameters for more information.

The following tables describe the additional parameters required to call the CreateHIT operation with an explicit HIT type ID and without a HIT type ID.

Calling CreateHIT with a HIT Type ID

The following parameters are specific to calling the CreateHIT operation with an explicit HIT type ID:

NameDescriptionRequired

Operation

The name of the operation.

Type: String

Valid Values: CreateHIT

Default: None

Yes

HITTypeId

The HIT type ID.

Type: String

Default: None

Yes

Question

The data the person completing the HIT uses to produce the results.

Type: String

Default: None

Constraints: Must be a QuestionForm data structure, an ExternalQuestion data structure, or an HTMLQuestion data structure. The XML question data must not be larger than 64 kilobytes (65,535 bytes) in size, including whitespace.

Either a Question parameter or a HITLayoutId parameter must be provided.

No

HITLayoutId

The HITLayoutId allows you to use a pre-existing HIT design with placeholder values and create an additional HIT by providing those values as HITLayoutParameters. For more information, see HITLayout.

Type: String

Default: None

Constraints: Must be a valid HITLayoutId, as obtained from the Amazon Mechanical Turk Requester website.

Either a Question parameter or a HITLayoutId parameter must be provided.

No

HITLayoutParameter

If the HITLayoutId is provided, any placeholder values must be filled in with values using the HITLayoutParameter structure. For more information, see HITLayout.

Type: HITLayoutParameter

Default: None

No

LifetimeInSeconds

The number of seconds after which the HIT is no longer available for users to accept. After the lifetime of the HIT has elapsed, the HIT no longer appears in HIT searches, even if not all of the HIT's assignments have been accepted.

Type: positive integer

Valid Values: any integer between 30 (30 seconds) and 31536000 (365 days).

Default: None

Yes

MaxAssignments

The number of times the HIT can be accepted and completed before the HIT becomes unavailable.

Type: positive integer

Valid Values: any integer between 1 and 1000000000 (1 billion).

Default: 1

No

AssignmentReviewPolicy

The Assignment-level Review Policy applies to the assignments under the HIT. You can specify for Mechanical Turk to take various actions based on the policy. For more information, see Assignment Review Policies.

Type: String

Valid Values: Must be a HIT Review Policy data structure, see HIT Review Policy.

Default: none

No

HITReviewPolicy

The HIT-level Review Policy applies to the HIT. You can specify for Mechanical Turk to take various actions based on the policy. For more information, see HIT Review Policies.

Type: String

Valid Values: Must be a HIT Review Policy data structure, see HIT Review Policy.

Default: none

No

RequesterAnnotation

An arbitrary data field. The RequesterAnnotation parameter lets your application attach arbitrary data to the HIT for tracking purposes. For example, this parameter could be an identifier internal to the Requester's application that corresponds with the HIT.

The RequesterAnnotation parameter for a HIT is only visible to the Requester who created the HIT. It is not shown to the Worker, or any other Requester.

The RequesterAnnotation parameter may be different for each HIT you submit. It does not affect how your HITs are grouped.

Type: String

Default: None

Constraints: must not be longer than 255 characters in length.

No

UniqueRequestToken

A unique identifier for this request. Allows you to retry the call on error without creating duplicate HITs. This is useful in cases such as network timeouts where it is unclear whether or not the call succeeded on the server. If the HIT already exists in the system from a previous call using the same UniqueRequestToken, subsequent calls will return a AWS.MechanicalTurk.HitAlreadyExists error with a message containing the HITId.

Type: String

Default: None

Constraints: must not be longer than 64 characters in length.

Note: It is your responsibility to ensure uniqueness of the token. The unique token expires after 24 hours. Subsequent calls using the same UniqueRequestToken made after the 24 hour limit could create duplicate HITs.

No

Calling CreateHIT Without a HIT Type ID

The following parameters are specific to calling the CreateHIT operation without a HIT type ID, letting Amazon Mechanical Turk determine the HIT type from the property values:

NameDescriptionRequired

Operation

The name of the operation

Type: String

Valid Values: CreateHIT

Default: None

Yes

Title

The title of the HIT. A title should be short and descriptive about the kind of task the HIT contains. On the Amazon Mechanical Turk web site, the HIT title appears in search results, and everywhere the HIT is mentioned.

Type: String

Default: None

Constraints: must not be more than 128 characters

Yes

Description

A general description of the HIT. A description includes detailed information about the kind of task the HIT contains. On the Amazon Mechanical Turk web site, the HIT description appears in the expanded view of search results, and in the HIT and assignment screens. A good description gives the user enough information to evaluate the HIT before accepting it.

Type: String

Default: None

Constraints: cannot be more than 2,000 characters in length

Yes

Question

The data the person completing the HIT uses to produce the results.

Type: String

Default: None

Constraints: Must be a QuestionForm data structure, an ExternalQuestion data structure, or an HTMLQuestion data structure. The XML question data must not be larger than 64 kilobytes (65,535 bytes) in size, including whitespace.

Either a Question parameter or a HITLayoutId parameter must be provided.

No

HITLayoutId

The HITLayoutId allows you to use a pre-existing HIT design with placeholder values and create an additional HIT by providing those values as HITLayoutParameters. For more information, see HITLayout.

Type: String

Default: None

Constraints: Must be a valid HITLayoutId, as obtained from the Amazon Mechanical Turk Requester website.

Either a Question parameter or a HITLayoutId parameter must be provided.

No

HITLayoutParameter

If the HITLayoutId is provided, any placeholder values must be filled in with values using the HITLayoutParameter structure. For more information, see HITLayout.

Type: HITLayoutParameter

Default: None

No

Reward

The amount of money the Requester will pay a Worker for successfully completing the HIT.

Type: Price data structure.

Default: None

Yes

AssignmentDurationInSeconds

The amount of time, in seconds, that a Worker has to complete the HIT after accepting it. If a Worker does not complete the assignment within the specified duration, the assignment is considered abandoned. If the HIT is still active (that is, its lifetime has not elapsed), the assignment becomes available for other users to find and accept.

Type: positive integer

Valid Values: any integer between 30 (30 seconds) and 31536000 (365 days).

Default: None

Yes

LifetimeInSeconds

An amount of time, in seconds, after which the HIT is no longer available for users to accept. After the lifetime of the HIT elapses, the HIT no longer appears in HIT searches, even if not all of the assignments for the HIT have been accepted.

Type: positive integer

Valid Values: any integer between 30 (30 seconds) and 31536000 (365 days).

Default: None

Yes

Keywords

One or more words or phrases that describe the HIT, separated by commas. These words are used in searches to find HITs.

Type: String

Default: None

Constraints: The complete string of keywords, including commas and spaces, cannot be more than 1,000 characters.

No

MaxAssignments

The number of times the HIT can be accepted and completed before the HIT becomes unavailable.

Type: positive integer

Valid Values: any integer between 1 and 1000000000 (1 billion).

Default: 1

No

AutoApprovalDelayInSeconds

The number of seconds after an assignment for the HIT has been submitted, after which the assignment is considered Approved automatically unless the Requester explicitly rejects it.

Type: non-negative integer

Valid Values: any integer between 0 (auto-approve results as soon as they are submitted) and 2592000 (30 days).

Default: 2592000 (30 days)

No

QualificationRequirement

A condition that a Worker's Qualifications must meet before the Worker is allowed to accept and complete the HIT.

Type: a QualificationRequirement data structure.

Default: None

Constraints: there can be no more than 10 QualificationRequirement data structures for each HIT.

No

AssignmentReviewPolicy

The Assignment-level Review Policy applies to the assignments under the HIT. You can specify for Mechanical Turk to take various actions based on the policy. For more information, see Assignment Review Policies.

Type: String

Valid Values: Must be a HIT Review Policy data structure, see HIT Review Policy.

Default: none

No

HITReviewPolicy

The HIT-level Review Policy applies to the HIT. You can specify for Mechanical Turk to take various actions based on the policy. For more information, see HIT Review Policies.

Type: String

Valid Values: Must be a HIT Review Policy data structure, see HIT Review Policy.

Default: none

No

RequesterAnnotation

An arbitrary data field. The RequesterAnnotation parameter lets your application attach arbitrary data to the HIT for tracking purposes. For example, the RequesterAnnotation parameter could be an identifier internal to the Requester's application that corresponds with the HIT.

Type: String

Default: None

Constraints: must not be longer than 255 characters in length.

No

UniqueRequestToken

A unique identifier for this request. Allows you to retry the call on error without creating duplicate HITs. This is useful in cases such as network timeouts where it is unclear whether or not the call succeeded on the server. If the HIT already exists in the system from a previous call using the same UniqueRequestToken, subsequent calls will return a AWS.MechanicalTurk.HitAlreadyExists error with a message containing the HITId.

Type: String

Default: None

Constraints: must not be longer than 64 characters in length.

Note: It is your responsibility to ensure uniqueness of the token. The unique token expires after 24 hours. Subsequent calls using the same UniqueRequestToken made after the 24 hour limit could create duplicate HITs.

No

Response Elements

A successful request for the CreateHIT operation includes the elements described in the following table.

NameDescription

HIT

Contains the newly created HIT data. For a description of the HIT data structure as it appears in responses, see the HIT Data Structure.

Examples

The following examples show how to use the CreateHIT operation.

Sample Request

The following are examples of REST requests.

Example Request (Query) Using CreateHIT with a HIT Type ID

The following example creates a simple HIT, using an explicit HIT type ID. The Question parameter takes a block of XML data as its value. See the QuestionForm data structure and the ExternalQuestion data structure for more information.

https://mechanicalturk.amazonaws.com/?Service=AWSMechanicalTurkRequester
&AWSAccessKeyId=[the Requester's Access Key ID]
&Version=2012-03-25
&Operation=CreateHIT
&Signature=[signature for this request]
&Timestamp=[your system's local time]
&HITTypeId=T100CN9P324W00EXAMPLE
&Question=[URL-encoded question data]
&LifetimeInSeconds=604800
          

Example Request (Query) Using CreateHIT With a HIT Type ID Using SimplePlurality/2011-09-01 Review Policy

The following example creates a simple HIT with a SimplePlurality/2011-09-01 Review Policy.

<CreateHITRequest>
    <HITTypeId>T100CN9P324W00EXAMPLE</HITTypeId>
    <Question>[CDATA block or XML Entity encoded]</Question>
    <LifetimeInSeconds>604800</LifetimeInSeconds>
    <AssignmentReviewPolicy>
        <PolicyName>ScoreMyKnownAnswers/2011-09-01</PolicyName>
        <Parameter>
            <Key>AnswerKey</Key>
            <MapEntry>
                <Key>QuestionId3</Key>   <!—correct answer is “B” -->
                <Value>B</Value>
            </MapEntry
            <MapEntry>
                <Key>QuestionId7</Key>  <!—correct answer is “A” -->
                <Value>A</Value>
            </MapEntry>
            <MapEntry>
                <Key>QuestionId15</Key>   <!—correct answer is “F” -->
                <Value>F</Value>
            </MapEntry>
            <MapEntry>
                <Key>QuestionId17</Key>   <!—correct answer is “C” -->
                <Value>C</Value>
            </MapEntry>
            <MapEntry>
                <Key>QuestionId18</Key>   <!—correct answer is “A” -->
                <Value>A</Value>
            </MapEntry>
        </Parameter>
        <Parameter>
           <Key>ExtendIfKnownAnswerScoreIsLessThan</Key>
           <Value>80</Value>
        </Parameter>
        <Parameter>
           <Key>ExtendMaximumAssignments</Key>
           <Value>3</Value>
        </Parameter>
    </AssignmentReviewPolicy>
</CreateHITRequest>         

Example Request (Query) Using CreateHIT Without a HIT Type ID

The following example creates a simple HIT with some properties, letting Amazon Mechanical Turk determine the HIT type ID from the property values. The Question parameter takes a block of XML data as its value. See the QuestionForm data structure and the ExternalQuestion data structure for more information.

https://mechanicalturk.amazonaws.com/?Service=AWSMechanicalTurkRequester
&AWSAccessKeyId=[the Requester's Access Key ID]
&Version=2012-03-25
&Operation=CreateHIT
&Signature=[signature for this request]
&Timestamp=[your system's local time]
&Title=Location%20and%20Photograph%20Identification
&Description=Select%20the%20image%20that%20best%20represents...
&Reward.1.Amount=5
&Reward.1.CurrencyCode=USD
&Question=[URL-encoded question data]
&AssignmentDurationInSeconds=30
&LifetimeInSeconds=604800
&Keywords=location,%20photograph,%20image,%20identification,%20opinion
         

Sample Response

Amazon Mechanical Turk might return the following response for the preceding requests.

<CreateHITResponse>
  <OperationRequest>
    <RequestId>ece2785b-6292-4b12-a60e-4c34847a7916</RequestId>
  </OperationRequest>
  <HIT>
    <Request>
      <IsValid>True</IsValid>
    </Request>
    <HITId>GBHZVQX3EHXZ2AYDY2T0</HITId>
    <HITTypeId>NYVZTQ1QVKJZXCYZCZVZ</HITTypeId>
  </HIT>
</CreateHITResponse>