The program FLEX1 will present one or two strings of characters successively at the center of the computer monitor, and then collect a keypress--recording the latency between the onset of the second string and the press of the key. The stimuli are provided to the program in a stimulus file (described below). Various aspects of the timing are controlled by the value of parameters which are also explained below. The program can be used for a wide range of priming or memory scanning experiments.
Data are output to a file that contains information about the character strings, the key pressed and the latency on each
Running the experiment
To run the program simply type FLEX1--you will be prompted for the name of
the input (stimulus) file. Or run the program by entering FLEX1 [myfile.nam], where [myfile.nam] is replaced
with the name of your file.
Note: Be sure the filename has less than 12 characters in it, including the dot and the three letter extension. When prompted for the filename, enter the entire name including the dot and the extension. Spaces are not allowed in the filename.
Stimulus (input) file
The input file can be created in any word processor as an "unformatted", "text-only" or "ascii" file. It can be given any valid name, and the user must provide the name of the file to FLEX1, as described above. An example of an input file appears on the next page.
The first line contains the number of trials.
Then the file must contain the following items for each trial, separated by commas:
The strings must be between 1 and 9 characters long (if you want to have a blank string make it a space.). There is a limit of 500 trials.
The following example shows how the program can be used to run a lexical decision experiment. Remember that you
may need to adjust aspects of the timing--so see the section on parameters.
Sample data file
The data are output to the file FLEX1.DAT. A sample of which is shown below. To view the file enter TYPE FLEX1.DAT, to print it enter PRINT FLEX1.DAT. See the following section for details about data analysis.
WARNING: Each time that FLEX1 is run it will DESTROY all old data files so be sure to view, print, copy or change the name of the data file before running the program again.
When prompted to "Press any key to begin", pressing the P will allow you to adjust the values of the parameters below. If you want one of the durations or time delays to be zero it is best to enter a small value (such as 1) instead of a 0. Note that all trials except the first [parameter 13] are randomly presented. The first [parameter 13] trials can be used for practice and could be the same for all runs of the program. Note also that a break will be given after [parameter 14] trials have been run since the last break.
1. duration of fixation plus (msec):
2. duration of prime display (msec): (default=1000)
4. inter-trial interval (msecs): (default=250)
5. trial feedback duration (msecs): (default=100)
6. Duration of error tone (msec): (default=500)
7. Interval between prime offset and target onset (msec): (default=500)
11. Y location of stimuli: (default=16000)
12. X location of central fixation point: (default=16383)
13. Number of initial trials to NOT randomize (default=0)
14. Number of trials before a break (default=50)
17. minimum allowed RT (msec): (default=100)
18. maximum allowed RT (msec): (default=1000)
19. target duration (msec): (default=1000)
Analyzing the data (You will need analysis program available below)
The program FLEXANAL will analyze data from FLEX1. Type FLEXANAL to run the program. The program will read the data file FLEX1.DAT, compute the mean reaction times separately for each different condition number, and output the means in a file called AFLEX.ANL. To look at the means type TYPE AFLEX.ANL. Only condition numbers 1 through 100 will be analyzed. Each time that FLEXANAL is run it will destroy any earlier AFLEX.ANL file.
Tips for using FLEX1