II assume that you want to do this because of the arguments made by Herbert Clark that both subjects and stimuli (words) should be considered random effects. In traditional analyses, such as repeated measures ANOVA, subjects are a random effects factor and words are considered fixed effects. Because of limitation of the software of the time, to get words to be random effect, one had to "flip" the dataset so that the words became the unit of analysis. I believe that the relevant publication for this is Clark 1973 which can be accessed here:
http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&uact=8&ved=0CDEQFjAB&url=http%3A%2F%2Fcseweb.ucsd.edu%2F~gary%2FPAPER-SUGGESTIONS%2Fclark-jvlvb-1973.pdf&ei=UVxOU-H3BvOnsATPpYGIBQ&usg=AFQjCNFYlTLJX85pIjakWlwJbvN5QMaZSQ&sig2=IPqYrzb_Mqa9PdopjZwngw
(If Url get broken search scholar.google.com for "Clark", "1973" and "language as fixed-effect-fallacy".
However, this was a controversial assertion which not everyone in the psycholinguistics and memory research area agreed to. You may want to see who cite this article and whether they are pro or con.
With newer software, factors in ANOVA can be defined as fixed (default) or random. You may want to take a look at the following reference (Note: I got it from scholar.google.com and it is supposed to be in APA format but scholar doesn't get it right):
Carson, R. J., & Beeson, C. M. (2013). Crossing language barriers:Using crossed random effects modelling in psycholinguistics research. Tutorials Quant Meth Psych, 9(1), 25-41.The article is available here:
www.tqmp.org/Content/vol09-1/p025/p025.pdf
This paper by Carson & Beeson (2013) provides background, rationale for doing an analysis where both subjects and words/stimuli are considered random effects, and provide SPSS examples using the MIXED procedure.
I never cared for Clark's argument but other have. There are people on SPSS who are unfamiliar with Clark's argument but are SPSS guru's and can provide advice on to do the analysis presented by Carson & Beeson.
Mike Palij