Comparing eye fixation and mouse cursor response modes in number line estimation

Recently, responding with eye fixations in the number line estimation (NLE) task was introduced. To determine if this new mode of responding replicates typical mouse cursor NLE results, 33 adults completed a 0 -1000 NLE task and responded with their eyes (eye condition) or the mouse (mouse condition), while their eyes were tracked. In the mouse condition, participants had lower error rates, higher response times, and looked at the three quartiles of the number line and back to the presented target number for a longer time compared to the eye condition. Despite these differences, both conditions elicited an "M-shaped pattern" in response times and error rates, thus replicating the typical NLE results in both response modes. Overall, a similar (strategic) process occurs for both response modes, suggesting that both are appropriate to use in the NLE task. Researchers should, however, proceed with caution, as there are mode-related constraints on response times and error rates.