• Blog
  • About
  • Publications
  • Videos
  • Workshops
  • CV
  • Contact Me
  • Hall of Fame
Menu

Andy's Brain Blog

Street Address
City, State, Zip
Phone Number
fMRI, Neuroimaging, and More

fmri, neuroimaging, and more

Andy's Brain Blog

  • Blog
  • About
  • Publications
  • Videos
  • Workshops
  • CV
  • Contact Me
  • Hall of Fame

E-Prime Tutorial #4: Lists, Procedures, and Attributes

June 10, 2017 Andrew Jahn

Once we've created the basic template of our experiment we turn our attention to flow control, or how to guide the subject to different parts of the experiment. In the previous video we created a basic Stroop experiment that went in a predetermined direction: The subject would encounter one Stroop trial, and then another, in exactly the order we had laid out. This was enough to qualify as an experiment, but most studies require more elements than that - randomization and counterbalancing, for example.

In this video we learn how to create these conditions with the List and Procedure objects, which lead the subject into different trials. If we think of the whole experiment as a large house, and of Procedures as rooms, then the List object is a series of signs guiding the subject into this room, and then that one. Once a specified number of rooms have been visited and something seen or done in each of them, the subject then leaves the house.

These Lists have levels, or rows representing individual trials and which Procedures they are in, and attributes, or columns specifying additional qualities about that trial. For example, a given trial may show the word red written in blue ink, have the correct response be the 'f' key, and be classified as "Incongruent". In this case we could specify four attributes: word (red), color (blue), correct response (f), and condition (incongruent). Attributes are similar to variables, in that an attribute can contain a different value depending on the trial. One trial may have a word color as blue, while another may have the word color be red. These attributes can be used in objects and sub-objects, and their values can be logged into E-Prime's output files.

Aside from assigning values to attributes, Lists can specify the trial order as either sequential or random, as well as specify how many times to loop over the list before exiting. This allows us to create a single template object for each condition and to modify it with the attributes specified in the list. For example, instead of making three different Slide objects display three different words, we can create three levels in the List object, create an attribute called "Word", and enter one word for each level: e.g., blue, red, and green. We now need only one template object and a text sub-object with brackets around our attribute name - in this case, [Word]. For a given trial the List will select a level and determine what the value of the Word attribute is. If we have selected a level where it contains the word "blue", then that word will replace [Word] in the Slide. The same method can be applied to any property in the object.

Using Lists and Procedures within those Lists we can stretch our experiment to any length that we want. Furthermore, attributes allow us to create template objects which are then populated with the attributes that we choose. Judicious use of these objects and attributes will save you considerable time and effort.

← E-Prime Tutorial #5: CounterbalancingE-Prime Tutorial #3: Duration, Termination, and Pre-Release →
Archive
  • September 2024
  • June 2024
  • March 2024
  • January 2024
  • June 2023
  • May 2023
  • April 2023
  • February 2022
  • January 2022
  • January 2021
  • December 2020
  • April 2020
  • December 2018
  • April 2018
  • January 2018
  • December 2017
  • August 2017
  • July 2017
  • June 2017
  • May 2017
  • April 2017
  • March 2017
  • January 2017
  • November 2016
  • August 2016
  • July 2016
  • February 2016
  • January 2016
  • September 2015
  • August 2015
  • July 2015
  • May 2015
  • April 2015
  • December 2014
  • October 2014
  • September 2014
  • August 2014
  • July 2014
  • June 2014
  • May 2014
  • April 2014
  • March 2014
  • February 2014
  • January 2014
  • December 2013
  • November 2013
  • October 2013
  • August 2013
  • July 2013
  • June 2013
  • May 2013
  • April 2013
  • March 2013
  • February 2013
  • January 2013
  • December 2012
  • November 2012
  • October 2012
  • September 2012
  • August 2012
  • July 2012
  • June 2012
  • April 2012
  • March 2012

What's on Andy's Brain this month?

Connect with Andy!

Powered by Squarespace