This study examined the influence of ideological incongruence and argument strength on the cognitive processing of political information among 73 healthy individuals (18- 80 years old). In the context of increasing political fragmentation and affective polarisation in The Netherlands, understanding the mechanisms of the “disconfirmation bias”—the tendency to exert significant cognitive effort to refute information not aligning with current beliefs and attitudes—is vital for maintaining deliberative democracy. Utilising a within-subjects design, participants evaluated 60 political arguments across six socio-political domains during an fMRI session, with response times (RT) serving as a proxy for cognitive effort. Linear Mixed-Effects Models (LMM) were conducted to assess whether argument strength moderates the cognitive demands of processing ideological incongruence. Results revealed no significant main effects for ideological incongruence or argument strength on response times. However, a significant interaction was observed, indicating that high argument strength positively moderated the disconfirmation bias. Specifically, strong incongruent arguments elicited the longest processing times. Exploratory analyses further suggested this effect was primarily driven by the right-wing cohort. These findings highlight that cognitive resistance is not a uniform response to all opposing views but is intensified by the epistemic quality of the challenge, here, argument strength. While the small effect size warrants caution, the results contribute to the debate on whether motivated reasoning reflects an irrational identity defence or a rational allocation of resources towards complex evidence.