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From: palan-t@acsu.buffalo.edu (thiagarajan palanivel)
Newsgroups: comp.human-factors
Subject: Re: Individual Differences
Message-ID: <80981@eerie.acsu.Buffalo.EDU>
Date: 24 Jun 91 16:51:38 GMT
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Andy Dent writes:

>Speaking in a non-scientific way, I have a concern that your definitions of
>style/principle will not test the true power of direct manipulation as used
>by "power users". Most Mac applications I've used have a wealth of command-key
>combinations and shift-click/option-click/command-click etc. mouse actions.

 I think that is a very  valid point. However, theoretically, I am working at a slightly higher level of abstraction than just style/principle. With the vast 
and diverse types of interfaces currently available, it would be difficult for 
me to test all of them, or to test enough of them to arrive at results 
generalizable to all of them. What I have tried to do instead (to make any 
results I may get more generalizable, especially to interfaces not considerered
in this study) is to list the dimensions on which interfaces differ. Then I havechosen some dimensions to study, and selected three types of interfaces that 
encompass a broad range on each of the dimensions. For example, I am considering
the dimensions of Orientation (Object vs. Process), Mode of Dialog (Verbal vs.
Physical), and Control of Dialog (User vs. System). I am not considering others
such as Data representation (Hierarchical vs. Gen. Network (as in Hypermedia)), and Multi-tasking capacity. That is why I have chosen to study three interfaces
which, while they may be well short of the state-of-the-art, mark some clear
distinctions with respect to the interests of my work. Of course, there are 
dis-advantages to this approach, chief among them being the loss of face 
validity for this study (You looked at such ancient interfaces ????, we have 
come a long way since then, you know !!).


>The skills or type of cognitive profile which makes a user extremely 
>productive on a CLI is (IMHO) directly applicable to the use of these "power-
>user" facilities. These facilities often lack visual feedback that you are
>in a "mini-mode" (unlike selection of graphics tools from a palette, or click
>and drag to get some rubberbanded outline).

>Without testing this kind of environment you run the risk of comparing the
>"athletes" of the CLI against the "joggers" of Direct Manipulation.


Again, I must agree that you have an extremely valid point. I am however going
to have two groups of subjects, novice, and expert, so as to isolate the effects
of experience and relevant knowledge. Since this is a University setting, I hope
to get subjects who will fit the very tight constraints I propose to use while
selecting subjects for either category. The effects of interface type, cognitive
abilities, and the interaction of the two, within a group of subjects, will 
therefore be relatively free of the "athletes" to "joggers" comparison effects.

Thanks to Andy Dent for the feedback. Comments ?

Raj Palanivel
Dept. of IE
SUNY @ Buffalo