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Fernando Ardenghi

"Strangers in a strange lab: How personality shapes our initial encounters with others"
(Oxford University Press, 2009) written by Dr. William Ickes

Chapter 11
" ... In summary, birds of a feather (couples with similar personalities) are not only more likely to flock together (that is, to select each other as marriage partners), but are also more satisfied with their relationships to the extent that they are globally similar. ... Although odd couples (those with globally mismatched personalities) may occasionally find each other and form committed relationships as well, the statistical odds of these odd couples being satisfied with each other tend to work against them. In contrast, the statistical odds for the success of committed relationships involving not-so-odd couples (those with globally similar personalities) are substantially better" page 25
" .... highly similar couples will probably always have an advantage over the odder, highly dissimilar ones. That doesn't mean that you can't win against long odds, but it does mean that it's a real gamble trying to make things work with a person you're just too different from." page 26


Fernando Ardenghi.
Buenos Aires.
[email protected]

James Houran, Ph.D.

The problem with the conclusions expoused by Dr. Ickes and heavily promoted by Fernando is that the data/evidence aren't as clear cut as they may seem to some. Indeed, there are other studies that point to the effectiveness of complementarity. Interested readers can find a brief review at:

Houran, J., Lange, R., Rentfrow, P. J., & Bruckner, K. H. (2004). Do online matchmaking tests work? An assessment of preliminary evidence for a publicized ‘predictive model of marital success.’ North American Journal of Psychology, 6, 507-526.

Also, a major methodological issue is how a researcher measures "satisfaction." Many relationship satisfaction measures -- like the DAS (which eHarmony uses) -- are really designed for married couples and the questions inherently ask about similarities across a number of issues versus how well the couple can accommodate each other and promote a process of adjustment and reaching agreement (which does not have to mean similar views) on issues that actually matter to the couple. In other words, it's neither surprising nor impressive that highly similar couples score higher on questionnaires that basically measure how similar two people are. Measuring similarity of attitude, values, etc. is not synonymous with "satisfaction."

Compatibility is actually a very idiosyncratic process. It's not similarity or dissimilarity per se that makes or breaks a couple, but rather a cognitive process used by each individual and the shared meaning and expectations a couple has.


James Houran, Ph.D.

Niki Payne

Steve Harvey's book isn't about online dating at all, so I find it interesting to see this book at the top of the list. I do believe that it is indeed recommended reading for all women. In fact, I'm such an advocate for his book that I preach it during my relationship workshops for sorority girls. When I initially came across this book, I didn't look twice at it until several people I've met suggested I read it since my approach to dating is to think and date like one. This book really reinforced the perspective I preach in both my writings and in the few workshops I've been asked to do.

In relation to Houran's comment regarding compatibility, I totally agree with him that compatibility is determinate upon the individuals involved because it is indeed a cognitive process. Through observations (and my own dating experiences), I've learned that people make themselves compatibile to others if they really like someone and are willing to give it a try and make it work. Generally speaking, to win the affection of your heart's desire, we consciously or subsconciously tend to conform or mold ourselves to the standards of that which our heart desires. Some people go through such extremes as to pretend to be someone they are not (as was displayed by Katherine Heigl's character in the recent film, "The Ugly Truth") while others are more subtle and simply bring to light aspects of an inner self that's buried deep within. The best way I can explain this is through the concept of colors. We are all made up of varying degrees of a color spectrum that represents our personalities. When opposites attract, they stay together because they brighten up their respective palest colors in an effort to make it work.

Tying this back around Dr. Houran's thoughts on compatibility, the cognitive process comes into play when knowing and understanding the color spectrum of your other half. It's at that point that you have to make a consious decision of whether or not you want to make it work and how much of an effort you are willing to exert to make it work. When relationships fail, I think that maybe it might be because one, or the other, or both simply stopped trying.

True compatibility, in my eyes, is when both parties can accept each other as individuals, flaws and all, and learn to work past those differences by fostering good communication and understanding. Through effective communication and mutual understanding, couples can accomodate each other, as Houran mentioned in his comment, by promoting a process of adjustment and reaching agreement (which sometimes means agreeing to disagree and being okay with that).

I really admire the work of Dr. James Houran and am a strong supporter of it. It's refreshing to come across an expert in this field with such a practical approach to compatibility that is applicable in the real world that I am dating in. Thank you for being my go-to resource when I need a leading expert to support my own personal theories.

Niki Payne
True Colors International
[email protected]

Fernando Ardenghi

Hi Dr. Houran:

It is always wonderful reading your comments!!!

Now, finishing year 2009, there is a collection of TOP 10 new&fresh Scientific Papers clearly showing the key to open the door for modern compatibility.

The key to open the door for modern compatibility is precisely personality similarity as the core of dyadic success (stability and satisfaction).

Charania & Ickes (2009)
paper: "Personality influences on marital satisfaction: Integrating the empirical evidence using the Actor-Partner Interdependence Model (APIM) model"
"... substantial level of inter-partner personality similarity for seven of the thirteen personality traits studied, with four of the similarity correlations exceeding 0.38 ..."

Rammstedt & Schupp (2008)
paper: "Only the congruent survive - Personality similarities in couples. Personality and Individual Differences"
".... Results reveal that among the Big Five dimensions, there are strong differences in spouses' congruences. While for Extraversion and Emotional Stability, congruence is close to zero, correlations averaging at 0.30 are found for Agreeableness, Conscientiousness, and Openness."

Dr. Ickes' opinion about this paper:
"I think a closer look will reveal that couples involving one high and one low conscientious partner tend to be dissatisfied because the conscientious partner feels that he or she has to 'take care of' the low conscientious partner. Couples involving one partner who is open to experience and one partner who is closed to experience will also tend to be dissatisfied because their political views and leisure time preferences are likely to diverge, and because the more 'adventurous' partner is likely to find the other partner somewhat boring. In initial interactions, an agreeable partner is able to compensate for the faults of a disagreeable partner, so that the interaction proceeds reasonably well. Having to constantly compensate for a disagreeable partner over a long period of time is a different proposition, however, and I can well imagine that the agreeable partner eventually gets disaffected and dissatisfied with having to do that so much."

Barelds & Dijkstra (2008)
paper: "Do People Know What They Want: A Similar or Complementary Partner?"
"In The Netherlands, where this study was conducted, almost 40% of the divorcees report mismatches in personalities as the major cause of their break-up (De Graaf, 2006; Amato and Previti, 2003). .... although several studies have revealed similarities between partners in their personalities (e.g., Buss, 1984; McCrae, Martin, Hrebícková, Urbánek, Boomsma et al., 2008) only few studies have investigated the extent to which similarity in personality leads to romantic attraction (Barelds and Dijkstra, 2007). From their finding that couples across age groups show the same partner similarities (McCrae et al. 2008) conclude that mate selection, rather than convergence over time, accounts for personality similarity among partners."
"Finally, the present study explored a recent issue uncovered by Eastwick and Finkel 2008; also Kurzban and Weeden, 2007; Todd, Penke, Fasolo, and Lenton, 2007 who found that people often report partner preferences that are not compatible with their choices in real life."

McCrae, Martin, Hrebícková, Urbánek, Boomsma et al. (2008)
paper: "Personality Trait Similarity Between Spouses in Four Cultures"
"... Most assortment effects were small, but correlations exceeding 0.40 were seen for a subset of traits, chiefly from the Openness and Agreeableness domains. ... This suggested that mate selection, rather than convergence over time, accounted for similarity"

Barelds & Dijkstra (2007)
paper: "Love at first sight or friends first? Ties among partner personality trait similarity, relationship onset, relationship quality, and love"
"... partner personality trait similarity was related to relationship quality as a function of both relationship onset and specific personality traits. "

Gonzaga, Campos & Bradbury (2007)
paper: "Similarity, convergence, and relationship satisfaction in dating and married couples."

Figueredo, Sefcek & Jones (2006)
paper: "The ideal romantic partner personality "
"... Individuals sought mates that were matches of themselves to some degree (a concept that we termed aspirational positive assortative mating) but also sought mates that were somewhat higher in Conscientiousness, Extraversion, Agreeableness, and Mate Value, but lower in Neuroticism than themselves."

Bekkers, van Aken & Denissen (2006)
paper: "Social Structure and Personality Assortment Among Married Couples"
"... Personality characteristics like agreeableness and neuroticism are good predictors of
marital conflicts and ultimately of union dissolution, even across different relationships
(Robins, Caspi & Moffitt, 2002). .... In sum: spouses with higher levels of neuroticism and openness, spouses with lower levels of agreeableness, and couples with more dissimilar personalities at the time of marriage are more likely to divorce."

Gaunt (2006)
paper:"Couple similarity and marital satisfaction: Are similar spouses happier?"

Amodio & Showers, 2005
paper: "Similarity breeds liking revisited: The moderating role of commitment"
While opposites attract for short term affairs, similarity is preferred for marriage.

Although none of the above papers use the 16PF normative personality test (they mostly use different versions of the normative Big5 personality test instead) and linear or logistic multivariate regression equations to calculate similarity, they clearly show a connection between personality similarity and marital happiness / dyadic success (stability and satisfaction) for some persons.

*Similarity is a word that has different meanings for different persons or companies, it exactly depends on how mathematically is defined.

Dr. Houran, are you & your team going to prepare a rebuttal for those papers showing personality similarity as the core of dyadic success (stability and satisfaction) ???

Kindest Regards.

Fernando Ardenghi.
Buenos Aires.
[email protected]

James Houran, Ph.D.

Hi Fernando!

The references you cite show that personality traits had inconsistent and low correlations with various measures of "relationship satisfaction." They are hardly convincing, and they do not support a strict similarity model. Read their conclusions again, as the different authors admit such.

As for my own work, I already have shown a strict similarity model is not optimal. My papers and presentations have been cited here and elsewhere numerous times. And it's not just me that holds that the core to relationship quality is cognitive in nature, not personality based.

Please see my paper for additional references on the subject:
Houran, J., & Lange, R. (2004). Expectations of finding a ‘soul mate’ with online dating. North American Journal of Psychology, 6, 297-308.

What I'd like to see is a study that shows a strict similarity model predicts relationship quality, as properly measured by IRT methods and which yields correlations of sufficient magnitude that it doesn't rely on large sample sizes to capitalize on small effects. All of those studies cited above have very small effect sizes -- so low that the influence of personality is much smaller than the unknown variables. I get similar, and even larger, effect sizes when using a complementarity model.

Oh well, I'm still waiting for that really convincing study! But those aren't it.


James Houran, Ph.D.

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