I am looking for the year of birth and death of Norman Triplett (the
first psychologist to make experiments in sport psychology) and of 
Coleman Griffith who was the first person to start a laboratory for
sport psychology

Hello husaro-ga,

According to the reply I received from Prof. Bernard Guerin, Norman
Triplett lived from 1861 to 1910.  (Prof. Guerin is the co-author of:
Vaughan, G. M., & Guerin, B. (1997). A neglected innovator in sports
psychology: Norman Triplett and the early history of competitive
performance. International Journal of the History of Sport, 14,
82-99.)

Markj-ga has noted in his comment the birth and death years for
Coleman Griffith.

- justaskscott-ga


Search terms used on Google:

"norman triplett"
"bernard guerin"

[I used other search terms as well, but these two terms led me to
Prof. Guerin, who provided the answer.]

I have reached a dead end on Norman Triplett.  I hope that another
researcher can find his birth/death years for you and complete this
answer.

Coleman Griffith lived from 1893-1966.  These dates were referenced in
the following online sources:
Bryn Mawr College: Conwy Lloyd Morgan, Mental Evolution, and The
Introduction to Comparative Psychology (in the 3rd paragraph)
http://www.brynmawr.edu/Acads/Psych/rwozniak/morgan.html

Early Historians of psychology and their texts (1870s-1921)(photograph
caption near bottom of page)
http://www.comnet.ca/~pballan/Historiog2.htm

These dates were confirmed with a search of the Social Security Death
Index:

Ancestry,com: SSDI Search Results
http://search.ancestry.com/cgi-bin/sse.dll?f3=Griffith&f4=Coleman&f23=&f0=&f1=&f2=&f20=&advqt=%2Fsearch%2Frectype%2Fvital%2Fssdi%2Fmain.htm&db=ssdi&ti=0&f13=&f15=&f14=&f12=&f9=&f8=&f10=&f6=&f5=&f7=&submit423.x=0&submit423.y=0

markj-ga

I have written a few co-authors of articles on Norman Triplett to see
if they know his years of birth and death.  I will let you know if I
receive a reply.