Cumulative response time from multiple sources in a single trial

[David McFarlane]

Joe,

Stock reminder:  1) I do not work for PST.  2) PST's trained staff 
takes any and all questions at 
http://support.pstnet.com/e%2Dprime/support/login.asp , and they 
strive to respond to all requests in 24-48 hours (although latest 
reports indicate more like 10 days) -- this is pretty much their 
substitute for proper documentation, so make full use of it.  3) If 
you do get an answer from PST Web Support, please extend the courtesy 
of posting their reply back here for the sake of others.

That said, here is my take ...

For info on getting key or button releases, see the "{key} 
nomenclature" topic of the online E-Basic Help.  Beyond that, I think 
the "Key Release" and "Multiple Response Collection" examples 
downloadable from PST would be places to look for more ideas.

-- David McFarlane, Professional Faultfinder


At 4/19/2010 02:19 PM Monday, you wrote:
>Hello all,
>
>I'm currently setting up a preferential looking study in which infants
>will be presented with various pictures on two different screens and
>their looking time at each picture type will be calculated. There will
>be approximately 25 trials in which 2 pictures will be simultaneously
>presented for 10 seconds on 2 screens (1 picture per screen). We are
>interested in the total amount of looking time towards either of the 2
>pictures within each individual trial, for each of the 25 trials.
>Looking times will be recorded using "Playstation"esque controllers,
>with which I've had no problems interfacing with Eprime.
>
>It is likely that infants will spend time within each trial looking
>back and forth between the two picture types. Coders are trained to
>press one specific button on the controller if the infant is viewing
>the screen on the left, and another specific button if the infant is
>viewing the screen on the right (the screens are separated such that
>it is obvious which of the two screens the infant is viewing). So, in
>order to calculate the cumulative amount of time spent viewing each
>picture, e-prime will need to keep track of the total amount of time
>that either of the two buttons was depressed within each trial and sum
>these values for each button.
>
>I've begun by creating 2 variables (one for each button that
>represents which screen the infant is viewing) as Summation objects
>(e.g., Dim OneDuration as summation; Dim ThreeDuration as summation)
>in the User Script. Next, in the experiment procedure I've placed an
>Inline script to initialize both of the new variables as new
>summations (e.g., Set OneDuration = New Summation; Set ThreeDuration =
>New Summation). The Pictures are displayed following this Inline
>object, which is in turn followed by a second Inline object with which
>I want to calculate the total amount of time that either of the two
>buttons on the controller were depressed. This is where I'm having
>trouble.
>
>I'm assuming that e-prime will need to keep track of the onset and
>offset time for each of the two buttons (i.e., objects) within each
>trial, then subtract the onset from the offset after the button has
>been released, then, if there are multiple instances of a button being
>pressed and released within a single trial, sum these amounts for each
>button after the trial has completed. The problem is, I'm a bit unsure
>of how to do this. Any ideas?
>
>I appreciate all of your help with this!
>
>Best Regards,
>
>Joe B.

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