In the blink of an eye: behavioural correlates of the confirmation bias effect

The confirmation bias effect-a well-documented cognitive bias in decision-making-is widely discussed in the literature. It refers to the tendency for information to be perceived as more credible when it aligns with personal beliefs, and less credible when it does not. Several studies have demonstrated that confirmation bias is associated with an increase in cognitive load, primarily due to the discomfort caused by cognitive dissonance. Since previous research has established a relationship between cognitive load and oculomotor behaviours, such as eye blink rate, one approach to detect confirmation bias is through the analysis of these oculomotor correlates. The present study aimed to explore the relationship between confirmation bias effect, cognitive load and participants' eye movement activity. To investigate potential behavioural correlates, the laboratory eye-tracking experiment was conducted. Participants (N = 52, 1705 observations) read short social media text messages with different valence (approving and disapproving), which either matched or conflicted with their pre-existing attitudes toward the topic. All stimuli were counterbalanced. Eye blink rate was measured as the dependent variable. The results indicated that the confirmation bias effect was indeed associated with changes in oculomotor activity. Specifically, there was a significant increase in eye blink rate for stimuli that were incongruent with participants' beliefs, and a decrease in blink frequency for congruent stimuli.