Change Blindness Question
I am running a change blindness study in which the subject must press the spacebar when s/he detects a change between two images, so I am alternating between two stimuli (560ms) and a mask (80ms). I want the subject to be able to press the spacebar at any time and jump to a free response trial to answer what changed before moving onto the next trial. I'm having problems getting this to work. At first I had the time column read rt:57>3 [the free response], 560, but after looking at the forums, I realized that this waits for the subject to press the spacebar. I'm unsure what to do here; should I have each time include a no response valid condition? The online manual suggests using ! as a means of automatic continuation, but doesn't say how to actually transcribe that (rt:57, 560!? rt:57, 0-560!?). How can I have the subject jump out of the stimuli presentation portion and into the free response? I am attaching my most current .csv file, as well as giving you access to the spreadsheet I'm using on google docs. Thanks in advance for your help!
note about automatic continuation
I didn't notice anyone else having posted this issue but through trial and error I have determined that if you want to use automatic continuation to end a trial that has more upcoming stimuli after a certain periof of no response, you must put two exclamation marks after your MinMax range in the styles file (e.g., 0-2000!!) AND two exclamation marks after the -1 in your rt statement (e.g., rt:-1!!,57).
This allowed me to skip to the next trial if there was no response after 2 seconds but if the spacebar was pushed before 2 seconds was up then it proceeded to the remaining stimuli associated with that trial.
Not sure why this works or if this actually helps you, but it hopefully explains the transcription issue - I was frustrated by this also.
Cheers.
trouble with Change blindness programming (case 33638)
[COLOR=#000000][FONT=Helvetica]I am having trouble programming a change blindness experiment using Direct RT. [/FONT][/COLOR]
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[COLOR=#000000][FONT=Helvetica]The main issue is that in the Time column I want Direct RT to show stimulus for 250 ms and then show the next stimulus [COLOR=inherit]for 250 ms [/COLOR]in the same trial, however, I also am hoping to program Direct Rt so that we can measure participants reaction time [U]IF/When[/U] they notice a change in the picture (by clicking on the spacebar). [/FONT][/COLOR]
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[COLOR=#000000][FONT=Helvetica]For each trial, the participant will see Stim 1 (picture1 ), Stim 2 (blank screen), Stim 3 (picture 2), Stim 4 (blank screen). This loop will be repeated several times. This is done to look like a flicker effect. So that participants won't notice the change for the first few stimuli (but the stimulus need to be timed in order for the flicker effect to work).[/FONT][/COLOR]
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[COLOR=#000000][FONT=Helvetica]So I want to programme for the stimulus to be presented for a specific amount of time (250ms) or until a response is made by the participant. However, from reading the manual it seems that this is not possible as I can only do one or the other? [COLOR=inherit] Is this possible on DIrect RT?[/COLOR][/FONT][/COLOR]
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[COLOR=#000000][FONT=Helvetica]I hope you can help. [/FONT][/COLOR]