# Research Methods Addendum

**URL:** <http://discourse.iapct.org/t/research-methods-addendum/9861>\
**Category:** CSG1994\
**Created:** [December 31, 1994, 7:15am UTC](http://discourse.iapct.org/t/research-methods-addendum/9861 "1994-12-31T07:15:11Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Richard\_Marken](http://discourse.iapct.org/letter_avatar_proxy/v4/letter/r/9fc348/32.png) [@Richard\_Marken](http://discourse.iapct.org/u/Richard_Marken)\
**Post date:** [December 31, 1994, 7:15am UTC](http://discourse.iapct.org/t/research-methods-addendum/9861/1 "1994-12-31T07:15:11Z")

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[From Rick Marken (941230.2320)]

Bruce Abbott (941230.1700 EST) --

I should note that I am aware that your example of using the IV-DV  
method to study the relationship between the RC transmitter stick and  
angles of the rudder and elevators on your plane does illustrate the use  
of this methodology to study a control system. As you note, the stick  
adjusts reference settings for the angle variables. Even without applying  
disturbances to test for controlled variables you learn some very  
interesting things about the behavior of this control system; you are  
learning precisely what you said you were learning -- the relationship  
between stick position and angle variables. You have demonstrated a  
use of the IV-DV method that CAN tell us something useful about control  
systems. Unfortunately, what you described is NOT the way the IV-DV  
approach is used in psychology. Psychologists do not have direct  
access to the reference inputs to living control systems; so the  
IV in psychological experiments is never variation in control system  
reference signals and the DV is generally not a measure of a (probable)  
controlled variable. In psychological experiments, the IV is an  
environmental variable; the only environmental variable that can be manipulat-  
ed by the experimenter (without active resistance from the control system) --  
the IV is what we call the disturbance variable in PCT. The DV is typically  
some arbitrary measure of system "output"; it's not likely to be a controlled  
variable becuase, if it were, it would show no relationship at all to  
the IV and would be rejected as an irrelevant response.

So my critique of IV-DV research applies most emphatically to the  
situation where we are forced to study control systems "from the  
outside" -- from whence there is no direct access to reference signals.  
In other words, it applies to all behavioral science research.

Best

Rick