Priming tasks (case 21060)

[m_gemtou]

Hi,

I was wondering if we can set up a priming task with Medialab. More specifically, I would like to know whether the timer that Medialab has can record very fast responses (and how many milliseconds) and whether the duration for timed items could be less than 1 second, if needed?

Thank you in advance,
Marilena

[jason_reed]

Priming tasks are better done in DirectRT. It is designed to work with timing on the millisecond level.

There are instructions and example files of a basic priming task described here in the DirectRT manual: http://www.empirisoft.com/directrt/help/directrt_samples_standard_priming.htm

If you do not have a copy of DirectRT, you can get a free 21-day trial license to try it out. Just download it from here on the Empirisoft website: http://www.empirisoft.com/Download.aspx?index=4. When you send the 14-character D-code to service@empirisoft.com, please make sure to ask for the 21-day trial license.

[m_gemtou]

Hi,

Thanks for the reply. I know that DirectRT is more accurate, but I was wondering about what Medialab can do and if their difference is only in accuracy. So, in the case of a priming task can Medialab record responses of millisecond and make the duration of timed items less than one second? It is not clear in the guidelines.

Thank you
Marilena

Priming tasks are better done in DirectRT. It is designed to work with timing on the millisecond level.

There are instructions and example files of a basic priming task described here in the DirectRT manual: http://www.empirisoft.com/directrt/help/directrt_samples_standard_priming.htm

If you do not have a copy of DirectRT, you can get a free 21-day trial license to try it out. Just download it from here on the Empirisoft website: http://www.empirisoft.com/Download.aspx?index=4. When you send the 14-character D-code to service@empirisoft.com, please make sure to ask for the 21-day trial license.

[jason_reed]

Marilena,


When it comes to presenting stimuli, MediaLab uses seconds as the unit of time the user can program. You can find more information about this using the duration parameter here in the MediaLab manual: http://www.empirisoft.com/medialab/help/queparameters.htm#duration.


There is a nice summary comparing DirectRT and MediaLab here in the DirectRT manual: http://www.empirisoft.com/directrt/help/directrt_introduction_and_key_concepts.htm


I've copied the text below if you would just like to read that information:


"DirectRT or MediaLab?


Many users ask us if they should use MediaLab, DirectRT or both. Whether you use one or both depends on what your needs are. MediaLab's strength is in its flexibility and ease-of-use with respect to traditional self-report questionnaires (many closed and open-ended question formats) and multi-media stimuli (movies, sound, html, word documents, powerpoint shows, etc.). You can use its point-and-click interface to quickly create an attractive questionnaire or experiment. It also creates data files in a horizontal (one row per subject) format that are very easy to work with and ready to analyze in Excel or SPSS. All of MediaLab's multi-media flexibility requires that it be a traditional Windows program, meaning that the any measures of display and response timing are also subject to the variations of the Windows operating environment. Thus, projects involving tasks like cognitive/perception trials (e.g., priming/lexical decision style tasks) that require measures of stimulus presentation and response times reliable and accurate to the millisecond are not as well-suited to MediaLab.


This is what DirectRT is excellent for. You get total control over timing because it's a DirectX application and not a "Windows" program. Basically, it was created to do what MediaLab can't do well?high precision cognitive/perception, "blocks of trials" types of tasks. You define your trials in a spreadsheet (e.g., Excel) so you can use your favourite spreadsheet app for editing the input files (a very nice benefit). Due to the nature of DirectRT experiments, the data files are vertical (e.g., one row per trial). This means it takes a bit more skill to collapse and analyze the data. Although some tasks could be easily done with either program, one or the other is usually a clear choice.


Both programs are stand alone, but they do work very well together as complements. A lot of people use both and embed DirectRT sessions within a more general MediaLab experiment. That's the gist of the difference."


Jason