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Dynamic visual search

edited May 2016 in OpenSesame

My query is a continuation of the earlier thread on a dynamic visual search experiment, started by my colleague. The experiment is a visual search task in which a variable number of objects move around randomly on screen throughout the trial. A target (defined by colour) may be present or absent on each trial.

As it stands, the array is on screen for a specified number of frames, after which a mouse cursor appears and is controlled by the user. A left click records the xy position of the cursor and the trial terminates and the next trial begins.

What I need is the following:

Even though the velocity of the objects is fixed (defined as v in the script below), the smaller arrays move noticeably faster than the larger arrays. Is this likely to be a hardware issue?

Rather than have the display run to a fixed number of frames (defined as NFrames in the script), after which the mouse cursor appears and a response can be made, I would like NFrame to specify the maximum run length of a trial before time-out. The trial should be terminated at any point before NFrame completion, where any movement of the mouse makes the cursor appear. When the left click takes place, the data logger records the coordinates and a new trial can begin.

I have defined the target in the script as TC (when it is present in the array) or as DS (when it is absent, and all objects are then the same colour). In the resulting data file, the xy coordinates of all the stimulus objects in the array are provided. Would you know: (i) whether the target is always assigned the same same object number in the data file (e.g., Stim1)? and (ii) whether those xy coordinates refer to the starting positions of the objects, or their positions at the end of the sequence?

Many thanks in advance! You can access the script at the link below (as I can't get the embed function to work)...


  • edited 4:20AM

    I have not yet received a reply to this query. Can anyone help?

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