Frequently asked questions - Amazon Mechanical Turk

Frequently asked questions

Use the following sections to get answers to frequently asked questions. If you need additional support, use the following link to contact Amazon Mechanical Turk:

Why aren't my tasks being completed?

There are a number of reasons why the tasks you post to Mechanical Turk aren't being completed. The most common reason is that the reward amount you specified isn't adequate to compensate workers for the time and effort they need to commit to your task to complete it. If you suspect this is the case, remove the HITs from Mechanical Turk by expiring them and experiment with reposting some of them at a higher reward amount.

Other common reasons include the following.

  • The qualification requirements for the task are so narrow that few, if any, workers meet the criteria to be eligible for the task.

  • The task interface has a technical issue that prevents workers from submitting it.

  • The assignment duration is set too short for workers to successfully complete the task in the time allowed.

How do I pull down HITs I created by mistake?

Use the UpdateExpirationForHIT operation and set the ExpireAt time to 0 to tell Mechanical Turk to immediately expire a HIT. Note that this won't prevent workers that have already accepted your HIT from completing and submitting it.

I expired my HITs. Why am I still getting submissions from workers?

If a worker accepts a HIT before it expires, they are still allowed to complete and submit the task until the assignment duration elapses. This protects the worker experience by letting them submit work on which they may have already spent a lot of time, even if you opt to take the HIT down.

Why are some of my task fields missing from my results?

A common mistake in building task interfaces is using the same name attribute for multiple form inputs. In those cases, only one of the input field values is returned. You should check your HTML to ensure that each input has a unique name.

Can I make some fields in my task interface required?

You can use HTML, JavaScript, or both to specify required fields and minimum or maximum values or perform other validations that prevent workers from submitting the task if it doesn't meet the requirements. To learn more about the types of form validation you can apply, see Client-side form validation on the Mozilla developer site.

How can I test my task interface?

The easiest way to test your task interface is to save it to an HTML file and open it in a browser. From the browser, you can go through all of the steps that a worker would perform in completing the task. If your task interface is built around a standard form element, you can't test submitting it, but you can test to ensure it works as you expect. If you use the crowd-form element from Crowd HTML Elements, you can test it by selecting Submit. When you submit from outside of Mechanical Turk, the results are displayed at the top of the window.

To fully test a task interface and the creation and retrieval of HITs, you can use the sandbox environment.

What is the difference between a HIT and an assignment?

A HIT is a single task that you create in Mechanical Turk. When workers accept a HIT, they get an assignment that gives them the right to submit their response. When you create a HIT, you can specify the maximum number of assignments that can be created for each HIT, which allows you to get multiple different worker responses for each task. For more information on HITs and assignments, see Amazon Mechanical Turk core concepts.

Can I view the HITs I create with the API in the requester website?

No, the requester website only displays HITs that are created from the requester website.

I published HITs in the sandbox environment. Why they aren't being completed?

The sandbox environment is a great way to test HITs without spending any money. However, because no money changes hands, there isn't any incentive for workers to complete your tasks. To complete your testing, create an account in the worker sandbox environment to complete the tasks yourself. Then, publish them in the production environment.

I incorrectly rejected some assignments. Can I reverse the rejection?

In the event that you reject an assignment but then discover that the issue was not the worker's fault, you can call ApproveAssignment to reverse the rejection, but only for assignments submitted in the last 30 days that haven't been deleted.

How do I filter the workers eligible to work on my task?

Mechanical Turk provides a qualifications system that allows you to use system-managed or custom criteria to limit the workers that can work on a task. For more information, see Selecting eligible workers.

How do I create a custom qualification?

You can create custom qualification types that allow you to filter workers eligible to work on your tasks using criteria based on their past performance on your tasks. For more information, see Working with custom qualification types.

Can I restrict how many HITs a worker can complete for my project?

Mechanical Turk doesn't provide a native capability to limit the number of HITs that a worker can contribute to a project or batch. To learn how to accomplish this using custom qualification types, see Working with custom qualification types. Before starting your project or batch, create a custom qualification type with a label such as Completed Enough of Project A and pecify that this type doesn't exist (DoesNotExist) in your qualification requirements for each HIT. When a worker reaches your threshold of HITs they can submit, you can assign this qualification type to them, after which they can't accept any HITs for the project.

Can I post HITs in languages other than English?

You can post HITs using any language, provided you note the required language in the title of your task. However, the number of available workers who are fluent in a given language varies greatly. It may take longer for your task to be completed or you may need to increase your reward amount if not enough workers are available.

Additional Mechanical Turk Resources