Posner cuing experiment
Overview. The PosnerCuing.psyexp program runs a version of Posner’s visual attention task. On each trial a cue is presented either to the left or right of fixation (or in both locations). A short time later a target appears at either a cued oruncued location. Subjects respond by pressing one of two keys to indicate the location of the target.
Details. Run the program by double-clicking on the PosnerCuing.psyexp file. This will launch PsychoPy with the experiment timeline loaded. Run the experiment by selecting “run” from the PsychoPy menu (the green running person). A dialog box will appear in which the student can optionally enter their name or initials. Any string entered will become the first part of the name of the data file.
On each trial a box is presented on each side of fixation. The cue is a brightening around one or both boxes. A target letter X is presented in one of the boxes shortly after the cue. Subjects respond by indicating the location of the target: z=left, /=right. The cue is fixed at 100 ms in duration. The cue-target interval in the excel file specifies the interval from the beginning of the cue until the onset of the target. (It is possible to use cue-target-intervals less than 100ms.) After a practice block of 18 trials, subjects serve in 5 test blocks of 54 trials each. Each block contains 3 replications of each of the 18 combinations of cue (left/right/neutral) * target (left/right) * cue-target interval (100/200/300ms).
Other details of the method can be learned by examining the timeline and the events in PsychoPy. In cases where attributes of the events are variable, the variables are typically specified in the provided Excel files.
Programming notes. If the ‘condition’ variable contains the word “neutral” then two cues will be presented: one at the location specified in the excel file, and another at the opposite location. (In other words, only one cue location need be specified in the file.)
Data analysis. The data are in a *.CSV file in the “data” folder in the Psych/Lab folder. Double-click on this file to open it in Excel. Each row corresponds to a trial. Entries in the column labeled condition show the condition for that trial. Keyresponse.RT contains the reaction time (in seconds). Keyresponse.corr codes whether the response was correct (1) or incorrect (0). The first one (or more) sets of trials might be practice and should not be analyzed. See the instructions elsewhere for creating a pivot table to summarize the data.