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 eurodate dating site 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). For example, Carter (2005) wrote that his first involvement as a research scientist with eHarmony was to conduct construct validity for a set of factors from a 1000+ item survey that had been administered to approximately 3,000 married couples. He also refers to replicating the factor structure with a second sample of couples. XV In addition, as can be gleaned from various sources, including the eHarmony patent (Buckwalter et al., 2004, 2008), this large sample of couples has been used to determine what combination of traits is found in couples who have the highest level of satisfaction.
The eHarmony research labs include research by Gian Gonzaga, Thomas Bradbury, and other relationship scientists ( The current eHarmony research facilities, which opened in spring of 2007, include a state-of-the-art laboratory for studying couple interaction
The sites also appear to use data collected from their members to improve their matching procedures. At eHarmony, users’ actions after they are sent matches (e.g., whether they click on particular matches to obtain more information) are used as input into the model for the particular users almost immediately. XVI Chemistry has had a post-meeting “chemistry check” in which members give feedback after a date. Helen Fisher has stated in several media interviews that she is using the data and feedback from the users to modify the Chemistry matching procedure. In addition, Fisher has referred to having data from 28,000 users and being prepared to publish the Chemistry’s matching procedure for peer review. XVII She has classified these users into different profiles and followed their dating experiences. According to interviews, these data have led to her conclusions that people with the priine and serotonin prefer each other while those with the personality type associated with testosterone are attracted to those with a personality type of estrogen.
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Finally, eHarmony is the industry leader in scientific research designed to answer basic research questions about relationships and contribute to peer-reviewed, academic research. As noted at the website for eharmonyLabs, “While some of the research we conduct is for product development, and therefore proprietary, much of our research is submitted for peer review and academic publication. ” XVIII Several online studies are advertised at the Lab’s website. In addition, a marriage study is currently underway which involves extensive data collected from couples, including observations of their interaction.