In the field of numerical cognition, researchers conventionally assess nonsymbolic numerical abilities with the help of number comparison tasks, in which participants need to compare two arrays. Many studies emphasized that visual (non-numerical) dimensions can serve as strategic cues and influence the decision on numerosity in these tasks. In this study, we suggest the use of a novel paradigm based on the change detection paradigm. Here, participants had to simultaneously pay attention to numerical changes and visual changes on a target non-numerical dimension (individual area, total area, field area, or density). Participants had to detect changes relative to the two dimensions and press response keys indicating either number change or visual change or press both keys. In such a double change detection paradigm, and unlike number comparison tasks, target and covarying dimensions cannot serve as cues to influence the numerical decision. We found that numerical change detection was excellent and stable across the conditions. Further, participants were more likely to falsely consider visual changes as numerical changes than the other way around. Lastly, when both dimensions varied, participants more frequently missed visual changes than numerical changes. Overall, our findings show that numerosity was the most salient visual dimension. From a methodological perspective, such a double change detection paradigm could be of critical interest to assess numerical abilities for future studies.