I am conducting a task in which I show people a series of different images. During the series of images, at random points, a white circle appears suddenly and people have to press the space bar as quickly as possible to register that they have seen the circle.
I am simply interested in whether people have bothered to press the space bar, either straight away or in the next few seconds after a circle flashes up. So in essence, I just want to log the times at which they press the space bar.
I have separate trials for each of the series of images, plus a trial for the target (the white circle).
These look like this (the first relates to the white circle, the second is representative of all of the image trials but the code is essentially the same for all of the images used):
<trial target>
/ stimulustimes = [0=targetPic; 101=erase]
/ trialduration = values.targetDuration
/ inputdevice=keyboard
/ validresponse = (" ")
</trial>
<trial image 1>
/ stimulustimes = [0=image1Pic; 1000=erase]
/ trialduration = values.exposureDuration
/ inputdevice=keyboard
/ validresponse = (" ")
</trial>
My problem is that this only seems to record a very few instances of the space bar being pressed rather than all of the keyboard presses that I make. For example, I went through the whole task and pressed the space bar at 12 different points (making sure these were in separate trials), and when I looked at the raw data, there were only two presses of the space bar that had been registered (i.e. response column in the raw data showed '57' rather than '0'). Is there any reason why this might be? I don't think it is a problem with my space bar as I am not having any problems at all in any other program.
Many thanks