Elsevier

Intelligence

Volume 73, March–April 2019, Pages 41-51
Intelligence

People tend to overestimate their romantic partner's intelligence even more than their own

https://doi.org/10.1016/j.intell.2019.01.004Get rights and content

Highlights

  • Males and females overestimated the IQ of their partners by ≈ 7 IQ points more than the overestimation of their own IQ.

  • Both females (r = 0.30) and males (r = 0.19) predicted their partner's IQ with some degree of accuracy.

  • Degree of IQ compatibility failed to relate to relationship satisfaction significantly.

Abstract

People can estimate their own and their romantic partner's intelligence (IQ) with some level of accuracy, which may facilitate the observation of assortative mating for IQ. However, the degree to which people may overestimate their own (IQ), as well as overestimate their romantic partner's IQ, is less well established. In the current study, we investigated four outstanding issues in this area. First, in a sample of 218 couples, we examined the degree to which people overestimate their own and their partner's IQ, on the basis of comparisons between self-estimated intelligence (SEI) and objectively measured IQ (Advanced Progressive Matrices). Secondly, we evaluated whether assortative mating for intelligence was driven principally by women (the males-compete/females choose model of sexual selection) or both women and men (the mutual mate model of sexual selection). Thirdly, we tested the hypothesis that assortative mating for intelligence may occur for both SEI and objective IQ. Finally, the possibility that degree of intellectual compatibility may relate positively to relationship satisfaction was examined. We found that people overestimated their own IQ (women and men ≈ 30 IQ points) and their partner's IQ (women = 38 IQ points; men = 36 IQ points). Furthermore, both women and men predicted their partner's IQ with some degree of accuracy (women: r = 0.30; men: r = 0.19). However, the numerical difference in the correlations was not found to be significant statistically. Finally, the degree of intellectual compatibility (objectively and subjectively assessed) failed to correlate significantly with relationship satisfaction for both sexes. It would appear that women and men participate in the process of mate selection, with respect to evaluating IQ, consistent with the mutual mate model of sexual selection. However, the personal benefits of intellectual compatibility seem less obvious.

Introduction

Humans can self-estimate their own intelligence with some degree of accuracy (Freund & Kasten, 2012), and the intelligence of others, too, based even on very limited information (Borkenau & Liebler, 1993). However, there is empirical evidence to suggest that humans tend to overestimate their cognitive capacities (the better-than-average effect; Mabe & West, 1982) and, theoretically, possibly the intelligence of their romantic partners (the positive illusion effect; Barelds & Dijkstra, 2009).1 Correspondingly, humans rate intelligence highly in a prospective romantic partner (Buss et al., 1990). Furthermore, assortative mating for intelligence is well established empirically with objective intelligence tests, and, to some degree, with self-estimates of intelligence (Bouchard & McGue, 1981; Escorial & Martín-Buro, 2012). However, precisely how and why assortative mating for intelligence occurs remains an open question (Robinson et al., 2017).

The males-compete/females-choose model of sexual selection (Stewart-Williams & Thomas, 2013) suggests that women should be better at discerning the intelligence of men, in comparison to a man's capacity to discern the intelligence of women. By contrast, the mutual mate model of sexual selection (Stewart-Williams & Thomas, 2013) suggests that women and men should be able to discern each other's intelligence about equally well. To-date, these competing theories have not been tested, in this context. Furthermore, some compatibility relationship theory (Gonzaga, Campos, & Bradbury, 2007; Huston & Houts, 1998) suggests the degree of assortative mating for intelligence across couples should correlate positively with romantic relationship satisfaction, which, arguably, would promote the continuance of assortative mating for intelligence. To-date, this hypothesis has also not been tested extensively.

In light of the above, this investigation had four primary purposes. First, to test for the better-than-average intelligence effect and the positive illusion effect for intelligence in romantic couples. Secondly, to test the males-compete/females-choose model versus the mutual mate choice model, by estimating the association between female ratings of male partner IQ and objective male partner IQ versus the association between male ratings of female partner IQ and objective female partner IQ. Thirdly, we attempted to replicate the assortative mating for intelligence effect with a fluid intelligence test, as well as with a self-estimation of intelligence scale. Finally, we estimated the association between degree of intelligence compatibility (subjective and objective) and relationship satisfaction.

Section snippets

Accuracy of estimating one's own IQ: correlational

A substantial amount of research has established a positive correlation between self-estimated intelligence (SEI) and objectively measured intelligence (r ≈ 0.30; Freund & Kasten, 2012; Gignac, Stough, & Loukomitis, 2004; Zajenkowski, Stolarski, Maciantowicz, Malesza, & Witowska, 2016). Thus, to some degree, people tend to have insight into their intellectual capacity. The correlation is not so large, however, as to suggest that SEI scores may be used as a proxy for objectively measured IQ

Accuracy of estimating one's own IQ: mean difference

Research in the broader area of the self-evaluation of abilities has found that, on average, people overestimate their abilities across a wide range of dimensions (Mabe & West, 1982). The phenomenon is often referred to as the ‘better-than-average-effect’ (Alicke & Govorun, 2005). With respect to intelligence, specifically, Heck, Simons, and Chabris (2018) asked a general community sample of Americans to respond to the following item: ‘I am more intelligent than the average person.’ They found

Accuracy of estimating romantic partner's intelligence

On average, humans state that they value intelligence highly in a prospective romantic partner (Buss et al., 1990). Furthermore, intelligence carries with it biological advantages that can be passed onto children (see Hagenaars et al., 2016, for example). However, in order for sexual selection for intelligence to occur, humans would need to be able to perceive or discern the intelligence of prospective mates with some degree of accuracy. Empirical research suggests that even strangers can

Are women better than men at discerning a romantic partner's intelligence?

According to the males-compete/females-choose model of sexual selection, males compete for the attention of women by displaying biologically and socially valuable characteristics to help women choose a partner with whom to mate (Darwin, 1871; Miller, 2011; Stewart-Williams & Thomas, 2013). Obviously, the characteristics displayed by men need to be perceptible to women, in order to facilitate the decision to choose one man over another. As noted above, some empirical research suggests that even

Assortative mating for intelligence

A positive correlation (r ≈ 0.30 to 0.40) between the objectively measured IQ scores of people in a romantic relationship has been reported (Van Leeuwen, Van den Berg, & Boomsma, 2008; Watson et al., 2004). Furthermore, the correlation does not appear to increase with age of the relationship, suggesting that the effect occurs at the selection stage (Mascie-Taylor, 1989). Consequently, the effect is known as assortative-mating for intelligence (Jensen, 1967). There is some evidence to suggest

Summary

It is well-established that people can predict, to some degree, their own intelligence as well as the intelligence of others. However, despite the observation of the better-than-average effect for several abilities/competencies, the degree to which people may overestimate their own (or their partner's) intelligence has not yet been established, on the basis of comparable self-estimated IQ and objectively estimated IQ scores. Consequently, in the current study, we investigated these effects

Sample

The original sample included 222 couples. However, one case did not have a Raven's IQ score and one case did not have a relationship satisfaction score. These two cases were omitted from the analyses. Additionally, two cases reported their ages as >65, therefore, we excluded these two cases, as well, due to the limitations of the Raven's IQ norms. Thus, the final sample consisted of 218 heterosexual couples (age Mmen = 28.00, SD = 9.25; age Mwomen = 27.27, SD = 9.16) who were recruited from the

Accuracy of IQ estimates

The descriptive statistics are reported in Table 1. As hypothesized, there was a positive correlation between self-estimated intelligence and objective intelligence (APM) for both women (r = 0.26, 95%CI: 0.12/0.38, p < .001) and men (r = 0.33, 95%CI: 0.13/0.49, p < .001). However, as can be seen in Fig. 2, both women and men overestimated their own IQs, when their self-ratings were compared against their performance on the objective IQ test: female mean IQ difference = 29.99 IQ points, 95%CI:

Discussion

We replicated the positive correlation between self-estimated IQ and objective IQ. However, we found that both women and men greatly overestimated their IQ, consistent with the better-than-average effect. People also overestimated their romantic partner's IQ, consistent with the positive illusion effect. We replicated the assortative mating for intelligence effect, on the basis of objectively measured intelligence, and extended the assortative mating for intelligence effect to self-estimated

Limitations

Although the sample size used in this investigation may be regarded as respectable (N = 218; power = 0.85 to detect a typical correlation of 0.20 as significant), unfortunately, established tests of the difference between correlations have been discovered to be underpowered. For example, when the population difference between two dependent non-overlapping correlations is equal to 0.70 vs. 0.60, a sample size of 100 was found to have power of only 0.34 (Silver, Hittner, & May, 2004). Based on

Conclusion

Assortative mating for intelligence is a robust, empirical effect, however, beyond the consistently observed assortative mating for intelligence correlation, relatively little is known about the processes by which the phenomenon arises. Based on the results of this investigation, it appears that both women and men may participate in the process of evaluation and selection, consistent with the mutual mate model of sexual selection.

Acknowledgement

This work was supported from grant no BST2018 funded by Faculty of Psychology of the University of Warsaw.

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      Borkenau and Liebler (1993) investigated intelligence estimates by a person’s cohabitant (in most cases their romantic partner) and reported a correlation of 0.29 with objectively measured intelligence. Recently, Gignac and Zajenkowski (2019) found that women’s estimates of their male romantic partner’s intelligence correlated at 0.30 with the partner’s actual intelligence, whereas men’s estimates only correlated at 0.19 with their female partner’s intelligence. Moreover, the authors found that both genders did not only overestimate their own but also their partner’s intelligence by around 30 IQ points, which again constitutes a large effect.

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