Using MEL in the Computer Lab

Computer Laboratory
Department of Psychology
(Release 95.1)

The Microcomputer Experimental Laboratory (MEL) is copyrighted and copy-protected software licensed to the Computer Lab. The entire system is installed on two computers-- the LAB25 and LAB26 machines in Rm 159A. Since this is a shared facility, there are certain practices which must be observed when using MEL. This document describes how to start learning MEL, how MEL is set up on the hard disk, and how you should use the system for your work.

Note: Some of the information following needs to be updated.

Learning to use MEL
Using MEL
- MEL directories
Creating your own experiments
- Base Experiments
- MEL Sample Experiments
Analyzing your MEL data

Learning to use MEL

The best way to learn to use MEL is to use the MEL Tutorial system installed on the computer. This set of programs contains a number of demonstrations and a set of tutorials which take you through all the phases of creating and running a MEL experiment. To start the tutorial, power on the computer and type: C:\>mel Change to \MEL directory and display the MEL menu C:\MEL>teach Starts the tutorial system (The prompt, "C:\MEL>" shows the current directory.) The TEACH program asks for your name and keeps track of the demonstrations and tutorials you have tried, so you can try a few and come back another time to try some more.

A printed Tutorial Guide to MEL is contained in the MEL documentation binders.(1) This guide describes the computer tutorials and illustrates how the MEL form system can be used to implement reaction time, questionnaire, and text comprehension experiments.

Once you have tried some of the tutorials listed below (or read the Tutorials Guide), you should read the MEL User's Guide, Chapter 2, "Basics of entering and modifying an experiment" through section 2.17 ("Experiment authoring hints").

Tutorial: Illustrates:
FRAME: filling out forms and getting help
EXP: labelling the experiment and declaring variables
TRIAL: setting number of trials and listing forms
INSERT: selecting words from stimulus lists

For additional background, use the TEACH program to do tutorials which take you through the steps of authoring an experiment from scratch:

Tutorial: Illustrates:
NEWEXP1: make a reaction time experiment from scratch
NEWEXP2: continue above, declaring independent variables
NEWEXP3: continue above, using inserts for stimulus sets

If your interest is in questionnaire experiments, try the QUESTION tutorial, then read Chapter 6 of the MEL User's Guide.

Using MEL

MEL directories

The files for the MEL system are organized in a set of subdirectories on the C drive. The directories are shown in Figure 1 and described below. The basic rule to observe is to leave these directories and files exactly as you find them: do not change any files or add any of your own files . You are free, however, to copy any of the base, sample, and font files to your own floppy disks.(2)
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(1) One copy of the MEL documentation binder is available to be borrowed from the Psychology Resource Center. The Computer Lab copies must remain in the lab.
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(2) The MEL executable programs (FORM.EXE, ANALYZE.EXE, EDIT.EXE, SUBJECT.EXE, SEQ.EXE) are copy-protected and you may not copy them. They will not run on any computer other than the lab machines on which it is installed.
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\MEL: Contains the executable MEL programs, common INCLUDE files, options files for data analysis, etc.
\MEL\BASE: Contains the MEL "base" experiments, a set of over 30 experiments of various types you may use as the base for designing a new experiment.
\MEL\FONTS: A library of various fonts for text and pictures.
\MEL\LOCAL: A collection of several locally-developed experiments.
\MEL\SAMPLE: A set of over 30 sample experiments, designed for instructional use. These can also be used as the basis for new experiments. However, they are more complex than the Base experiments, since they include features such as summary of results for the subject and the ability to run an abbreviated version of the experiment in "instructor mode".
\MEL\TUTORS: The MEL Tutorial Package
\MEL\WINDOWS: Window and Help files for Tutors and MEL programs


                              +---------+
                              |  \MEL   |
                              +---------+
                                   |
     +-----------------------------|-----------------------------+
     |              |              |              |              |
+---------+    +---------+    +---------+    +---------+    +---------+
|  BASE   |    |  FONTS  |    | SAMPLE  |    | TUTORS  |    | WINDOWS |
+---------+    +---------+    +---------+    +---------+    +---------+


  Figure 1:  MEL directories

Creating your own experiments

The easiest way to create your own MEL experiment is to start with one of the Base or Sample experiments which is close to what you want to do and modify the forms in that experiment. When you create your own experiment, you must save your work on your own floppy disk rather than on the hard drive on the LAB25 computer. The section below describes how to do this for one of the base experiments.

Base Experiments

The MEL base experiments provide a set of prototypes you can adapt for your own experiments. These experiments are listed in Figure 2. The form (.FRM) files contain extensive notes and comments describing the purpose of each form in the experiment. The MEL User's Guide describes most of these experiments in detail and suggests extension experiments. See the following chapters of the User's Guide for discussion of how these experiments are set up:

Chapter: Base experiments
3: Basic reaction time experiment (B_RT)
5: MEL techniques for choice reaction time and list learning experiments.
6: Questionnaire experiments
7: Text comprehension and reading time experiments

    Directory of  C:\MEL\BASE                                      
                                                                   
   Sect Experiment     Illustrates
   3.   B_RT    .FRM   simple reaction time: physical/name match   
   5.1  B_CHOICE.FRM   choice reaction time experiments            
   5.2  B_SENT  .FRM   present sentences, store several indep. vars
   5.3  B_SHAPE .FRM   present line graphics, code for mult monitors
   5.4  B_FONT  .FRM   graphics font experiment                    
   5.5  B_PICTUR.FRM   presentation of PC Paint picture files      
   5.6  B_BOXVOC.FRM   response box and voice key input            
   5.7  B_YES   .FRM   record only yes responses                   
   5.8  B_C_EXIT.FRM   exit based on block performance criterion   
   5.9  B_CREP  .FRM   counterbalance conditions & record subj. vars.
   5.10 B_PROBE .FRM   dual task: matching and tone probe          
   5.11 B_RTSUM .FRM   displaying graph to Ss, calc statistics     
   5.12 B_LIST  .FRM   list learning with recognition test         
   5.12 B_LIST_S.FRM   list learning with free recall              
   5.13 B_PRISON.FRM   prisoner's dilema social bargaining         
   5.14 B_SCAN  .FRM   memory scanning, code to randomize stimuli  
   5.15 B_MFSCAN.FRM   multi-frame scanning changing frame         
   5.16 B_MRSCAN.FRM   multi-response recording, continuous task   
   5.17 B_TAPE  .FRM   record responses to events on tape recorder 
   6.3  B_QUES  .FRM   multiple choice questionnaire               
   6.4  B_QMATCH.FRM   questionaire matching                       
   6.5  B_QPOLY .FRM   multiple choice, bipolar, match, open-ended 
   6.6  B_QSCALE.FRM   bipolar questions with context displays     
   6.7  B_QBRNCH.FRM   questionnaire with branching                
   6.8  B_QSUBJ .FRM   subject background/debriefing questionnaire 
   6.9  B_QPICT .FRM   questionnaire with pictures                 
   7.3  B_TEXT  .FRM   text comprehension: RSVP & moving window    
   7.4  B_TEXTQ .FRM   line-by-line text comprehension & questions 
        MUSIC   .FRM   play musical tunes                          
        SHOWFONT.FRM   graphics font demo                          
        TIMETEST.FRM   timing test utility                         
                                                                   

  Figure 2:  Contents of \MEL\BASE directory

To use one of these, first copy it to your floppy disk, then run the FORM program to examine and modify the base experiment. The example below shows how you would do this starting with the base choice reaction time experiment, B_CHOICE.FRM.

C:\MEL>cd base change to BASE subdirectory C:\MEL\BASE>copy b_choice.frm a:mychoice.frm copy to A drive as MYCHOICE.FRM C:\MEL\BASE>form a:mychoice run FORM program Note that the file B_CHOICE.FRM is copied under a new name, MYCHOICE.FRM. On the Experiment form, you should also change the 3 slots on the FILES: line to the same new name (MYCHOICE):

 ================== EXPERIMENT SPECIFICATIONS #1 ========= a:\mychoice ===
 AUTHOR ___________ CREATION DATE 10-5-89  LAST UPDATE 10-5-89
 FILES:   EXP mychoice  DATA mychoice   INSERT mychoice  INCLUDE  __________

Then, when you save your work (F4 key) or generate the experiment (F3 key), the experiment and data files will be created on your own floppy disk under the new name you have chosen.

The base experiments are complete--you can compile and run them as is, but usually contain only a small number of stimulus items. Note that if you only want to change the stimuli that are used in a given experiment in many cases you need only change the stimulus items listed on the INSERT form.

When you run one of the base experiments, the notes and comments in the forms are displayed on the screens. Once you understand the purpose of each screen, you can delete these lines from the form with the F5 (delete field) key.

Printing experiment forms

You may wish to print out the forms for one or more of the base (or sample) experiments. You can do this from the FORM program while viewing the forms for any experiment.

First make sure that the printer is switched on and there is paper in the printer. Then, press the F8 (Form functions) key and select "Print form" from the menu. You will be prompted as follows:

Enter name of output ("prn" for printer): prn press Print outline? (y/n) type y Print all forms? (y/n) type y You can also print to a file by specifying a file name (e.g., a:myform.txt) instead of the print device prn.

MEL Sample Experiments

The MEL Sample Experiments are complete versions of classic experiments in perception, memory and cognition, and social psychology. Most of them include the following features:

practice trials, in which the subject must achieve a given level of performance before proceeding to the experimental trials;
summary of the subject's results, presented in tabular and graphical form;
can run an abbreviated version of the experiment in "instructor mode".

An annotated list of the Sample Experiments is shown in Figure 3.

                                                                   
    Directory of  C:\MEL\SAMPLE                                    
                                                                   
   BLINDSP .FRM   Visual blind spot                                
   ENCODE  .FRM   Roles of cues and context on recall and recognition
   GRAF    .FRM   produce graphs of subject performance            
   GRAF    .INC      "      "    "     "        "                  
   GRAPH   .FRM      "      "    "     "        "                  
   GRF_FORM.TXT      "      "    "     "        "                  
   HSH     .FRM   selective attention and response competition     
   ICON    .FRM   visual iconic memory: partial report vs whole report
   LEXDEC  .FRM   lexical decision task                            
   ORGANIZE.FRM   free recall of organized lists                   
   PERTEST .FRM   personality scales: anomy, locus of control, self-esteem, etc.
   PHONE   .FRM   mnemonic characteristics of telephone design     
   PINI    .FRM   perceptual matching                              
   PROBLEM .FRM   role of imagery in verbal problem solving        
   READING .FRM   reading comprehension experiment                 
   README  .GRF                                                    
   ROTATE  .FRM   mental rotation task                             
   RSVP    .FRM   sample experiment files                          
   SENPIC  .FRM   sentence - picture verification                  
   SERPOS  .FRM   serial position effects in free recall           
   SHOWFONT.FRM   display MEL fonts                                
   SIGNAL  .FRM   signal detection                                 
   SPACING .FRM   effect of spaced practice on recall of names     
   STERN   .FRM   Sternberg memory scanning task                   
   STM     .FRM   effects of rehearsal on short-term memory        
   SYMBDIST.FRM   symbolic distance effect                         
   VGADEMO .FRM   demonstrates VGA graphics                        
                                                                   

 Figure 3:  Contents of \MEL\SAMPLE directory

Trying the Sample Experiments

Compiled versions of a number of the Sample Experiments are available in the Lab. They are set up so that you can run them on any IBM/PC. You can try one or more of them as follows:

Obtain the disk(s) labelled "MEL RUN Disk" and "MEL Sample Experiments" in Room 159C. For the IBM PS/2 workstations, all of the files are on one 3.5" disk labelled "MEL RUN/SAMPLE".
Boot the computer with the MEL Run disk in Drive A and (for the Zenith machines) the MEL Sample Experiments disk in Drive B. A list of the available experiments will be shown on the screen.
At the prompt, type RUN expname press RETURN where expname is the name of the experiment you wish to try.
In the Subject Information screen, enter a subject number and session number: +----------------------------------------------------------+ | | | Subject Number (1..100, 0=No data logging) type 0 | | Session Number (1..32754) type 1 | | | | No data will be logged | | IS THIS OK (Y/N)? type Y | | | +----------------------------------------------------------+
A shortened version of the experiment can be run in "Instructor Mode". At the first instruction screen, when it says PRESS THE SPACEBAR TO BEGIN THE EXPERIMENT type ctrl-I (press the CTRL key and type I) instead of pressing spacebar. (You can also terminate any MEL program by holding down both SHIFT keys and CTRL at the same time.)

Analyzing your MEL data

ANALYZE program

The ANALYZE program provides facilities for basic data summaries, data screening, plotting, and conversion of MEL data files to SAS, SPSSX, BMDP, and other programs. For a hands-on introduction to MEL data analysis, run the analyze tutorials from the TEACH program:

ANALYZE basic analysis tutor
ANLZQUES analysis of questionaire tutor
ANLZTEXT analysis of text experiment tutor

The use of this program is explained in the following chapters in the MEL User's Guide:

Chapter: Base experiments
4: Basic analysis of data
6: Analysis of Questionnaires (Section 6.11)
9: Output to Standard Statistical Packages
10: Analysis of Variance

The ANALYZE program is used for all MEL data analysis.(3) To run ANALYZE, with your experiment form and data file (expname.DAT) on a floppy disk in the A: drive, type:

C:\MEL>ANALYZE a:expname
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(3) For analysis of variance, you use an ANOVA form in ANALYZE. When you press PF3 (Process) the program directs you to run a separate ANOVA program.
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Overview of ANALYZE

ANALYZE knows all the variables in your data file.
Specify your data analysis on forms. Except for the MAIN specifications form, each form corresponds roughly to one procedure (PROC step) in SAS. The ANALYZE forms are:
- MAIN SPECS - List notes about your analysis, and specify the names of data and output files.
- PLOT SPECS - Produce line and bar graphs, select response variable, specify independent variables
- LIST SPECS - Produce descriptive statistics (mean, std., etc)
- OUTPUT DATA SPECS - Output MEL data for analysis by SAS/SPSS/etc.
- ANOVA SPECS - Carry out an analysis of variance
Controlling the analysis. All MEL analysis forms allow you to specify how the analysis is to be done:
- Filters: Select observations to be analyzed based on values of any of the variables. FILTER sex[1] analyze males only FILTER respac[1] analyze correct trials only FILTER resprt[100:2000] RT between 100 and 2000 msec. FILTER subject[1:10,12:20] exclude subject 11 Filters correspond to IF-selection statements in a SAS data step or a WHERE clause in a PROC step. For example, the filter sex[1] produces a subset of the data like this SAS data step: data males; set expdata; if sex = 1;
- Conditionals: Specify how to break the data down by conditions of the experiment. CONDITIONALS sex marginal stats for sex, ignoring other factors CONDITIONALS gp,sex stats for all gp x sex groups
- BY processing: Specify a variable used to repeat a plot or analysis for each distinct value of that variable. This works exactly like the BY statement in SAS.

Sample analysis forms

The MEL base directory contains three complete examples of analysis forms and some sample data for common experiments: B_MULT.ANL multiple choice experiments B_RT .ANL reaction time experiments B_TEXT.ANL text/reading time experiments You can use these files to analyze your own experiments in just the same way that you might use the base experiment .FRM files to construct the experiment itself. To adapt one of these to your analysis, change the file names on the MAIN specifications form to match your data file, and change the names of the dependent, independent, filter and conditional variables as appropriate on the other forms.

To use one of these, first copy it to your floppy disk, then run the ANALYZE program to examine and modify the analysis form. The example below shows how you would do this starting with the base reaction time experiment analysis, B_RT.ANL:

C:\MEL>cd base change to BASE subdirectory C:\MEL\BASE>copy b_rt.anl a:myrt.anl copy to A drive as MYRT.ANL C:\MEL\BASE>analyze a:myrt run ANALYZE program Note that the file B_RT.ANL is copied under a new name, MYRT.ANL. On the MAIN form, you should also change the 3 slots for the input and output file names to match your own files.

 +---------------------------------------------------------------------------+
 |                                                                           |
 |  =================== MAIN SPECIFICATIONS        #1 ========= a:\myrt =====
 |  AUTHOR ______________   DATE CREATED 01-5-91  DATE UPDATED 01-5-91
 |  DEFAULT INPUT FILE myrt.dat     
 |  DEFAULT OUTPUT FILE myrt.out    
 |  VARIABLE TABLE OUTPUT FILE myrt.var
 |                                                                           |
 +---------------------------------------------------------------------------+

Then, when you save your work (F4 key) or process an analysis, (F3 key), the analysis and output files will be created on your own floppy disk under the new name you have chosen.

Printing analysis graphs

The GRAFPLUS program in the MEL directory allows you to print a graph displayed on the screen by pressing the F7 key. To use GRAFPLUS, you must run it (just once) before you start the ANALYZE program.(4) For the Zenith 159 (EGA screen) and NEC P5 printer the command is: C:\MEL>GRAFPLUS =I14 Printing graphics screens with GRAFPLUS takes a long time. If you decide you don't want to wait for the graph to finish printing, press .

You can also capture a graph from ANALYZE to a PC Paint format file (.PCX) which can be incorporated as a figure in a document (e.g., with Word Perfect, Word Star). To do this, press Alt-F7 while viewing the graph. The computer beeps twice to indicate that the graph has been saved. If your analysis form is named MYRT.ANL, the graph files will be named MYRT001.PCX, MYRT002.PCX, etc. When you exit the ANALYZE program, copy these files to your floppy disk and erase them from the \MEL directory.
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(4) If you start work by running the MEL.BAT file to change to the \MEL directory and display the MEL menu, GRAFPLUS is automatically loaded for you, so you need not use the GRAFPLUS command.
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