Long-term study shows romantic partners mutually shape political party support

A new longitudinal study suggests that intimate partners mutually influence each other’s support for political parties over time. The research found that a shift in one person’s support for a party was predictive of a similar shift in their partner’s support the following year, a process that may contribute to political alignment within couples and broader societal polarization. The findings were published in Personality and Social Psychology Bulletin.

Political preferences are often similar within families, particularly between parents and children. However, less is known about how political views might be shaped during adulthood, especially within the context of a long-term romantic relationship. Prior studies have shown that partners often hold similar political beliefs, but it has been difficult to determine if this is because people choose partners who already agree with them or if they gradually influence each other over the years.

The authors of the new study sought to examine if this similarity is a result of ongoing influence. They wanted to test whether a change in one partner’s political stance could predict a future change in the other’s. To do this, they used a large dataset from New Zealand, a country with a multi-party system. This setting allowed them to see if any influence was specific to one or two major parties or if it occurred across a wider ideological spectrum, including smaller parties focused on issues like environmentalism, indigenous rights, and libertarianism.

To conduct their investigation, the researchers analyzed data from the New Zealand Attitudes and Values Study, a large-scale project that has tracked thousands of individuals over many years. Their analysis focused on 1,613 woman-man couples who participated in the study for up to 10 consecutive years. Participants annually rated their level of support for six different political parties on a scale from one (strongly oppose) to seven (strongly support).

The study employed a sophisticated statistical model designed for longitudinal data from couples. This technique allowed the researchers to separate two different aspects of a person’s political support. First, it identified each individual’s stable, long-term average level of support for a given party. Second, it isolated the small, year-to-year fluctuations or deviations from that personal average. This separation is important because it allows for a more precise test of influence over time.

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The analysis then examined whether a fluctuation in one partner’s party support in a given year could predict a similar fluctuation in the other partner’s support in the subsequent year. This was done while accounting for the fact that couples already tend to have similar average levels of support.

The results showed a consistent pattern of mutual influence. For all six political parties examined, a temporary increase in one partner’s support for that party was associated with a subsequent increase in the other partner’s support one year later. This finding suggests that partners are not just politically similar from the start of their relationship but continue to shape one another’s specific party preferences over time.

This influence also appeared to be a two-way street. The researchers tested whether men had a stronger effect on women’s views or if the reverse was true. They found that the strength of influence was generally equal between partners. With only one exception, the effect of men on women’s party support was just as strong as the effect of women on men’s support.

The single exception involved the libertarian Association of Consumers and Taxpayers Party, where men’s changing support had a slightly stronger influence on women’s subsequent support than the other way around. For the other five parties, including the two largest and three other smaller parties, the influence was symmetrical. This challenges the idea that one partner, typically the man, is the primary driver of a couple’s political identity.

An additional analysis explored whether this dynamic of influence applied to a person’s general political orientation, which was measured on a scale from extremely liberal to extremely conservative. In this case, the pattern was different. While partners tended to be similar in their overall political orientation, changes in one partner’s self-rated orientation did not predict changes in the other’s over time. This suggests that the influence partners have on each other may be more about support for specific parties and their platforms than about shifting a person’s fundamental ideological identity.

The researchers acknowledge some limitations of their work. The study focused on established, long-term, cohabiting couples in New Zealand, so the findings may not apply to all types of relationships or to couples in other countries with different political systems. Because the couples were already in established relationships, the study also cannot entirely separate the effects of ongoing influence from the possibility that people initially select partners who are politically similar to them.

Future research could explore these dynamics in newer relationships to better understand the interplay between partner selection and later influence. Additional studies could also investigate the specific mechanisms of this influence, such as how political discussions, media consumption, or conflict avoidance might play a role in this process. Examining whether these shifts in expressed support translate to actual behaviors like voting is another important avenue for exploration.

The study, “The Interpersonal Transmission of Political Party Support in Intimate Relationships,” was authored by Sam Fluit, Nickola C. Overall, Danny Osborne, Matthew D. Hammond, and Chris G. Sibley.