One frequently sees references to the experimentally determined memory
span of various animals, in particular the goldfish. We would like to
know by what means these memory spans have been determined. Any other
available information about the methodology of testing memory span
would also be appreciated.

Hi, 

Both of the referances I found are PDF's and if you can't veiw those
then use the other link I have there which will bring them up on the
Google search and you can use the View as HTML function.

http://scottyflag.hypermart.net/BettaRef1100.pdf 

http://www.biu.ac.il/LS/staff/susswein/Schwarz%201998.PDF 

Google Search for those two. 
://www.google.com/search?sourceid=navclient&ie=UTF-8&oe=UTF-8&q=Laudien+%2Bgoldfish

Other links

Goldfish calculus
http://www.biomedcentral.com/news/20010129/01/

Brain calculus: neural integration and persistent activity
http://info.med.yale.edu/neurobio/mccormick/ pubs/persistn_v.pdf 

COGNITIVE SCIENCE AND PSYCHOLOGY 
http://www.imprint-academic.demon.co.uk/SPECIAL/03_15.html


Google Query
memory +goldfish +test

thanks

webadept-ga

I do agree with you.  I would expect some original content("from the
experience of the researcher") in addition to any weblinks, if it is
going to be an answer.