23 Aug In media interviews, Fisher has argued that falling in love depends on both similarity and complementarity XII
Chemistry's survey and matching process focus more on chemistry than compatibility. The survey has approximately 150 questions, with responses to questions designed to measure four personality types, each associated with a particular hormone or chemical: Explorer (Dopamine), Builder (Serotonin), Director (Testerone), and Negotiator (Estrogen). For example, users are asked in one question to indicate the length of their index finger relative to their ring finger (which can be related to the level of testosterone). In another question, users are asked to recognize sincere versus insincere faces, which Fisher argues is related to estrogen (being a Negotiator) (Gottlieb, 2006). Based on their responses to a variety of questions, people are classified according to a primary personality type and a secondary personality type. For example, in one recent interview she stated, "I think we are unconsciously attracted to those who complement ourselves biologically, as well as socially, psychologically, and intellectually. I think we fall in love with someone who has a different chemical profile for dopamine, serotonin, estrogen, and testerone that complements our own. This is the basic premise behind my work with Chemistry" XIII She has also stated that it is the prominent neurochemical within an individual that determines whether the preference is for similarity or complementarity. Explorers and Builders will prefer similarity, whereas Directors and Negotiators will select each other (Fisher, 2009). XIV
In-house empirical research. The sites also refer to their own scientific research for the purpose of developing their matching procedures. eHarmony has stated that their patented scientific model for matching is based on data collected from 5,000 married couples. Although I could not find the detail of this study (see also discussion of this omission by Houran, Lange, Rentfrow, & Bruckner, 2004), the study is referred to in various published sources (e.g., Gottlieb, 2006).