Stephen,
Thank you for this very timely reference. For some reason this
semester, a large number of students in my methods courses seem to be
over emphasizing issues of generalizability and while almost (if not
completely) ignoring threats to internal and construct validity.
In-class demonstration projects that have always worked well in the
past don't seem to be working with the students this semester. (I
just finished grading one of these assignments, so this is fresh in
my mind right now.)
Every semester I do a "study" on ESP with my students that consists
of two conditions, with 20 trials in each. It's the standard "think
about what the next image will be" then see if they get it correct or
not. They score themselves after each trial, with a brief break in
between conditions. I pick something different from semester to
semester as the "ESP enhancing object" to be used for the 2nd
condition, where all of the images are presented in exactly the same
order as the first condition. Needless to say, I always get a
significant effect with scores in the second condition being higher.
In past semesters almost all students pick up on the issue of carry
over and sequence effects threatening the validity of the study. This
semester the vast majority of students are focusing on the sample (ie
students in the class) not being representative of the larger
population as the most important threat/limitation, and very few are
even mentioning testing as a threat in the design even though in my
mind it's staring them in the face.
I was beating my head against the wall while grading the papers
tonight and realizing I needed to go back over the threats to
experimental validity (again) and why threats to internal validity
were important. So this article came at just the right time for me to
discuss it with them in class tomorrow... well, really not tomorrow
since class is in about 8 hours now...
- Marc
At 12:14 AM 11/2/2007, [EMAIL PROTECTED] wrote:
This just out: Swimming with dolphins (aka "Dolphin-assisted
Therapy") does not cure autism, mental retardation, depression,
"infantile neurosis", dermatitis, or bad breath (ok, I made that
last one up).
Our old friend Scott Lilienfeld, along with Lori Marino, just
published a review saying so (http://tinyurl.com/yvtc2u ).
No word on the effectiveness of swimming with da fishes.
Stephen
Marino, L, & Lilienfeld, S. (2007). Dolphin-assisted therapy: More
flawed data and more flawed conclusions. Anthrozoos, 20, 239-249.
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Stephen L. Black, Ph.D.
Professor of Psychology, Emeritus
Bishop's University e-mail: [EMAIL PROTECTED]
2600 College St.
Sherbrooke QC J1M 1Z7
Canada
=============================================
G. Marc Turner, PhD, MEd, Network+, MCP
Senior Lecturer & Technology Coordinator
Department of Psychology
Texas State University-San Marcos
San Marcos, TX 78666
phone: (512)245-2526
email: [EMAIL PROTECTED]
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