The source of a river is often difficult to find. More often than not, rivers originate from multiple small-water sources and creeks that trickle down, often underground, until they merge in larger streams and eventually become a river. The situation is not much different for scientific disciplines. Cross-cultural psychology started about forty years ago as a separate discipline, but its intellectual parental disciplines are much older. Since its inception, the field has grown considerably. Indeed, it may even be fair to argue that, as a scientific discipline, cross-cultural psychology has come of age. There are a few journals (such as the Journal of Cross-Cultural Psychology, the Journal of Cross Cultural Management and the International Journal of Intercultural Relations) that are entirely devoted to the field, and there are many more journals that publish cross-cultural studies on a regular basis. All mainstream psychology journals have published cross-cultural studies. In addition, there is a professional organisation that is exclusively devoted to cross-cultural psychology (the International Association for Cross-Cultural Psychology). Both the association and the Journal of Cross-Cultural Psychology were launched at about the same time forty years ago, which seems to provide sufficient institutional reasons for defining this as the beginning of the discipline.

There is a time-honoured tradition in academia of writing a liber amicorum for a senior at the end of a typically successful career in university. But, as we know from ethnography, even rituals with a seemingly similar purpose come with much cultural variation. The idea of a combination of a universal theme and local variations is applicable to this book in a double sense.

First, it explains why the book has been written. Ype Poortinga is no longer Professor of Cross-Cultural Psychology at Tilburg University, the Netherlands, but has become an emeritus professor. This book is a liber amicorum dedicated to Ype as the founding (and still active) father of cross-cultural psychology in Tilburg and a key international player in the field. Yet, we deviate from the implicit recipe of the liber amicorum. This variation is mainly inspired by Ype's preferences. We think that a book with an up-to-date overview of modern theories and models in cross-cultural psychology will give him much more pleasure than a selection of chapters with anecdotes from his colourful past, in however lively a manner these are described. History is important in the book, not as anecdotes, but as references to the state of cross-cultural psychology forty years ago and to its current state. We take stock of cross-cultural psychology of the last forty years, which roughly spans Ype's professional career as well as the rise of empirical cross-cultural psychology.

The chapter starts from the above quotation by Tom Smith, who complained in a book on cross-cultural survey methods that comparability issues in cross-cultural surveys are more often mentioned than addressed. In a similar vein, Bollen, Entwistle and Alderson (1993) found in a meta-analysis of macrocomparative studies that equivalence is infrequently addressed. The situation in cross-cultural psychology is not much different; there is a widely acknowledged, shared awareness of potential pitfalls of direct cross-cultural score comparisons, but the sensitivity for the issue is insufficiently accompanied by tests of instrument adequacy in a specific study. It was argued in the first chapter by the editors that method issues are at the core of cross-cultural psychology. This chapter discusses one specific method issue, namely possible sources of bias in cross-cultural studies and the ramifications of bias for the cross-cultural comparability of scores. The editors mentioned in their chapter that the methodological problems of cross-cultural studies were already described seventy years ago and that many empirical researchers, methodologists and psychometricians have tried to tackle these problems. The question is addressed here to what extent we have advanced in this field. The present chapter deals with the question of how we should evaluate the current situation with regard to the study of bias.

The problem at hand

Culture is the elephant of Sufi legend – complicated, obscure, and ponderous, a daunting Rorschach of puzzling complexity. Kynna, a character in Renault's (2002) Funeral Games, confronts an alien culture with this reaction:

The use of culture as a variable of interest in scientific psychology yields studies reporting arresting differences between cultural groups in whatever response is of interest to the psychologist – be it pace of life, helping behavior, public staring, physical proximity, the content of complaint letters to government officials, or apologizing. These observed differences provoke intriguing speculations about their origins. Such speculations are often embedded in “thick description” and comparison of the social systems in question, are historically informed, and consider institutionally diverse factors that may lead to the different observed outcomes. Scholars present these “explanations” with experience and insight into the cultures involved. Because most readers are novices with respect to the cultures concerned, they are persuaded by the sophisticated argumentation on offer. But is it right?

This chapter describes how we can develop and test models of cross-cultural differences. We argue that an analytical approach to culture is adequate to explain cross-cultural differences but that we should try to be as specific as possible in such explanations. Saying that a particular Chinese person has a strong family orientation (compared with a Westerner) because he or she is Chinese does not tell us much. It is more informative to say that Chinese have a strong family orientation because they have been socialized for greater dependency on the family compared with persons in Western cultures. Our approach focuses on the identification of cultural elements that can explain such cross-cultural differences; we then show how these elements perform their explanatory role.

Although once considered to be at the margins of psychological science, the study of culture has blossomed into one of the most important areas of research today. Studies involving cultural variables appear more frequently than ever before in mainstream journals in developmental, clinical, personality, and social psychology, as well as in specialty journals such as the Journal of Cross-Cultural Psychology, Culture and Psychology, International Journal of Intercultural Relations, and the Journal of Cross Cultural Management (van de Vijver, 2006). Theorists are also increasingly incorporating culture as an important variable into their theories and models of psychological processes.

The methodological backbone spurring the blossoming of cultural science in psychology is cross-cultural research, in which two or more cultural groups are compared on psychological variables of interest. This is true regardless of the theoretical approach or perspective one adopts in understanding cultural influences on mind and behavior. For instance, methodological differences used to exist between those who called themselves cross-cultural psychologists versus those who called themselves cultural psychologists, with the former basing most of their work on cross-cultural comparison and the latter arguing that such comparisons were unwarranted, unjustified, and unnecessary (Greenfield, 1997; Shweder, 1999). Today, however, even those who call themselves cultural psychologists clearly use cross-cultural research methods as the method of choice in conducting research (e.g., Heine et al., 2001; Kitayama, Mesquita, & Karasawa, 2006; Markus, Uchida, Omoregie, Townsend, & Kitayama, 2006).