FLEX1--FLexible EXperiment Software

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Overview

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 trial.

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:

• number of characters in the first string
• the first character string
• number of characters in the second string
• the second character string
• the condition number (which must be included but can be ignored)
• the correct key.

The character strings and the correct key must be in single quotes. The program is case-sensitive (i.e., upper and lower case are different). Thus, you might want to be careful when you specify what the correct keypresses are--and be sure that the CAPS LOCK button is not on when you begin to collect data if you expect all responses to be lower case.

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.

Program parameters

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): (default=1000)
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

• The input file that FLEX1 reads must be in the same directory as the FLEX1 program.
  
  
• It is a good idea to create a small file for input to the FLEX1 program that runs only a small number of trials (like 10 or 20), to be sure that you are entering the description of the stimuli correctly.
  
  
• Note that the condition number in FLEX1 does not alter the operation of the program. Instead, it is simply a number that gets written to the data file along with the results from each trial. That number is then used by FLEXANAL when the data are analyzed: trials with the same condition number will be analyzed together.
  
  
• If you want to include some practice trials in your experiment you can adjust parameter 13 of the program so that the first N trials are not randomly mixed with the others. (Where N refers to the number of practice trials you want.) You need to then be sure that the first N trials specified in your input file are the ones that you want to be used for practice. It also would be a good idea to give these trials their own condition number so that they will not be analyzed with the "real" trials!
  
  
• Remember, when you run FLEX1 the program will DESTROY any existing versions of the data file FLEX1.DAT. Similarly, when you run FLEXANAL that program will destroy any existing versions of FLEX1.ANL. Thus, after you run a subject, you should analyze the data and then rename the data file and the analysis file (if you want to keep them).

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