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encapsulation</title></head><body>
<div>I'd be interested in hearing the evidence supporting the case for
visual programming representations. I agree with Ralph that the
burden of proof is on the proponents, but of the evidence that I've
read, it seems to me that a stronger statement can be made: That
visual programming is as hard or harder than textual
programming.</div>
<div><br></div>
<div>------</div>
<div><references annotation=true></div>
<div>First, there's the work by Marion Petre (replicated by Tom Moher)
that shows that even "experts" at visual programming
environments are actually much better at textual programming
languages:</div>
<div><br></div>
<div>Petre, M., & Green, T. R. G. (1990, ). <i>Where to draw the
line with text: Some claims by logic designers about graphics in
notation.</i> Paper presented at the INTERACT'90, Cambridge, England,
27-31 August.</div>
<div>Moher, T. G., Mak, D. C., Blumenthal, B., & Leventhal, L. M.
(1993). Comparing the comprehensibility of textual and graphical
programs: The case for Petri Nets. In C. R. Cook, J. C. Scholtz, &
J. C. Spohrer (Eds.), <i>Empirical Studies of Programmers: Fifth
Workshop</i> . Norwood, NJ: Ablex.</div>
<div><br></div>
<div>She has gone on to do a nice analysis suggesting that visual
forms are just as hard to deal with as textual forms.</div>
<div><br></div>
<div>Petre, M., & Green, T. R. G. (1993). Learning to read
graphics: Some evidence that 'seeing' an information display is an
acquired skill.<i> Journal of Visual Languages and Computing, 4</i>,
55-70.</div>
<div><br></div>
<div>There's the more recent work on KidSim/Cocoa which showed that
students have all the same problems programming in textual forms as
they do in visual rules. (Clayton Lewis at CHI96 or CHI7 -- I don't
have the reference here.)</div>
<div><br></div>
<div>Finally, there's all the work on algorithm animations which, thus
far, has not shown any learning benefits.</div>
<div><br></div>
<div>Stasko, J. T., Badre, A., & Lewis, C. (1993). Do algorithm
animations assist learning? An empirical study and analysis,
<i>Proceedings of INTERCHI'93</i> (pp. 61-66). Amsterdam, The
Netherlands: ACM.</div>
<div></references)</div>
<div>------------</div>
<div><br></div>
<div>Does anyone know of any evidence that supports the benefit of
visual representations for programs? I'm not saying that there
are no benefits of visual representations. The challenge is
figuring out what those benefits are.</div>
<div><br></div>
<div>Mark</div>
<div><br></div>
<div>At 2:20 PM -0600 1/25/99, Ralph E. Johnson wrote:</div>
<div>>At 3:56 AM 1/25/99, Hrefna "Gu•mundsdÛttir"
wrote:</div>
<div>>>On Saturday, January 23, 1999 6:56 PM, Andrew C.
Greenberg </div>
<div>>>> I'd be pleased to be educated to the contrary, but
it seems to me that</div>
<div>>>> Jen's suggestion that graphics are always better for
"really large"</div>
<div>>>> programs, indeed, even "always good" for
large programs need not always </div>
<div>>>be</div>
<div>>>> the case.</div>
<div>>></div>
<div>>>It may a bit 'strong' to say that graphics are 'always
good', but can you </div>
<div>>>point out an area where this does not hold?</div>
<div>></div>
<div>>You have it backward. People have been saying for
decades that</div>
<div>>visual representations for programs are essential. The
proponents</div>
<div>>of VPLs and CASE tools make similar arguments. UML is
the latest</div>
<div>>example. However, there is NOT ONE EXAMPLE of a system
that delivers</div>
<div>>on its promises. Very specialized systems like Stella
or GUI builders</div>
<div>>are certainly useful, and general purpose systems like
LabView are</div>
<div>>good for non programmers. AVL is a nice system, but it
has problems,</div>
<div>>and I bet I could make a better system in Smalltalk that was
text-based.</div>
<div>>Andy's point was that, as a programmer, he had yet to find a
system that </div>
<div>>was as fast and powerful for him as textual programming.
</div>
<div><br></div>
<div>--------------------------</div>
<div>Mark Guzdial : Georgia Tech : College of Computing : Atlanta, GA
30332-0280</div>
<div>(404) 894-5618 : Fax (404) 894-0673 : guzdial@cc.gatech.edu</div>
<div>http://www.cc.gatech.edu/gvu/people/Faculty/Mark.Guzdial.html</div
>
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