|
|
|
Forum Newbie
Group: Forum Members
Last Login: 4/28/2008 11:09:41 AM
Posts: 6,
Visits: 32
|
|
| I have a lot of stimuli in my experiment and the edata file containes many many columns I'm sur I will not use for data analysis. I would like to know which timestamp is necessary and the best to track timing of each stimulu (Starttime/Finishtime, Onsettime/offsettime, Target onsettime/taget offstetime)? In fact I need the best timestamp of stimulus to enter in the general linear model. Thanks a lot for your help! Aimée de Vanssay
|
|
|
|
|
Forum MVP
Group: Administrators
Last Login: Yesterday @ 10:30:44 PM
Posts: 549,
Visits: 1,198
|
|
| The OnsetTime is the timestamp as to when the object begins to execute its action (draw, play, etc). The effective duration of the object can typically be determined by taking the value of the OnsetTime of the NEXT object minus the previous/current one. If the next object does not clear out the screen completely then this cannot be considered. Other considerations are the rise/fall of the type of monitor to determine the true time "on screen". Any RT (response time) values you receive are based relative to this value (unless you view the RTTime which is based from begin of experiment). If you are analyzing the effective duration it took for a subject to respond based on seeing the stimulus, then you need to subtract the position of the stimulus based on refresh rate and rise time. For example, an RT of 300 if the stimulus is at the top of screen. If the stimulus is in the middle of the screen and on a CRT with 60hz, then 300 - aprx 8 would result in a 292 ms response time. It is not light reading, but the "critical timing chapter" in the user's guide goes into these topics more in depth. Many of the tutorials of the getting started guide go into creating an experiment from scratch, collecting data, and performing some analysis on them also. -Brandon
|
|
|
|
