Adding to existing knowledge regarding correlations between low cognitive ability and propensity toward prejudice, a new study by the University of Queensland shows that less intelligent people tend to express more prejudicial attitudes against same-sex couples.

Titled “The Cognitive Roots of Prejudice Towards Same-Sex Couples: An Analysis of an Australian National Sample,” authored by Francisco Perales and published in the peer-reviewed journal Intelligence, this is the first study to analyze the associations between attitudes towards LGBT issues and cognitive ability on a non-U.S. sample.

Previous research indicates that lower general intelligence in childhood predicts anti-homosexual prejudice in adulthood. For instance, a Brock University study titled “Bright Minds and Dark Attitudes,” published in Psychological Science, showed that lower intelligence predicts greater prejudice, predominantly through low inter-group contact and right-wing ideology.

Professor Francisco Perales’ study analyzed data from 11,654 Australians who participated in the Household, Income and Labour Dynamics in Australia (HILDA) survey. HILDA, a large household-based longitudinal survey, is the first survey of this kind in Australia, and it provides longitudinal data about Australian residents on subjective well-being, family dynamics, economic well-being, and more.

Cognitive ability was assessed using the following three cognitive ability measures.

The Digit Span Backwards test – Used in clinical neuropsychology, and considered to be one of the most influential working memory models in the last century, this test is used for assessing working memory capacity.

The National Adult Reading test – Developed and published in the early 1980s, often used in clinical settings, and on patients with dementia in neuropsychological research and practice, this test is used for estimating premorbid intelligence levels.

The Symbol Digit Modalities test – Meant to provide a quick screening for organic cerebral dysfunction in individuals 8 years and older, the Symbol Digit Modalities test is a relatively culture-free test that detects cognitive impairment in a matter of minutes.

Study participants who scored lower in the three cognitive ability measures used in this study were more likely to disagree with statements promoting equal rights for homosexual couples and LGBT population. Interestingly, the pattern, study author wrote, is more pronounced for verbal ability.

Furthermore, the association between low cognitive ability and prejudicial attitudes against same-sex couples held in the presence of economic and socio-demographic variables, such as education.

“High cognitive ability leads to lower prejudice, net of a large set of confounds. Results hold across different ability measures and are strongest for verbal ability. Education partially mediates, but does not moderate, the effect of ability,” study author Francisco Perales of the University of Queensland wrote.

In a statement supplied to PsyPost, Perales added that, “despite the significance and contemporaneity of the subject matter, few studies have specifically addressed the links between cognitive ability and attitudes towards LGBT issues.”

In order to counter and combat prejudice against same-sex couples and LGBT individuals, Perales said, we need to improve the general level of cognitive ability within the population, and increase participation in higher education.