During the past twelve years or so I have been carrying out several linguistic and psycholinguistic studies on the relationship between cognitive and linguistic categories. The impetus for summarizing this work in book form came from Sidney Greenbaum. I then had to embark on the task of spelling out and developing the theoretical approach underlying my previous research work.

In this venture I was supported by many people who gave me an opportunity to discuss my ideas with them. In particular I would like to mention Professor Greenbaum, who read the whole draft in instalments and saved me from at least the worst blunders, and Professor Richard Hudson and two of his doctoral students, And Rosta and Nik Gisborne, with whom I met regularly during several months on my sabbatical in 1992. Richard Hudson also read most of the chapters, and I owe much to his criticism and insightful suggestions. Much of what is good (I hope) in this book is due to them, and I cannot thank them enough for their interest and support.

The studies were conducted with the help of many research assistants. Some of them were not merely helping with the technical side but were acting more in the nature of collaborators, participating in planning and taking on responsibility for data collection and analysis: Neta Bargai, Laura Canetti, Alon Halter, Dalia Kelly, Neta Ofer, Liat Ozer, Ruth Pat-Horenczyck, Anat Rappoport-Moscovich, and Smadar Sapir.