Individual-level analyses are gaining increasing attention in recent psychological research. Historically, cognitive psychology has predominantly followed a nomothetic approach. Our work emphasizes the need for a more idiographic perspective in cognitive research, highlighting the importance of understanding variability within individuals.
This poster presents a re-analysis of the dataset by Tünnermann and Scharlau (2021) to investigate intra-individual variability in visual attention capacity, as formalized in the Theory of Visual Attention (TVA). The dataset comprises seven participants, each providing between 10,000 and 20,000 temporal-order judgments across multiple sessions over several days. Using Bayesian analysis, we examined trends in variability and the stability of overall processing capacity and orientation saliency within individuals. While some participants demonstrated learning effects across sessions, others maintained relatively stable overall processing capacities, fluctuating around a consistent value. Orientation saliency showed diverse patterns across participants. In some cases, it was a stable effect, consistently shifting the weight toward the salient probe, as expected from previous studies. In others, it affected the distribution of attentional resources depending on the number of days participants were involved. For some individuals, saliency fluctuated considerably, and in certain instances, the saliency effect was entirely absent. Additionally, we conducted an experiment to assess within-day variability, systematically accounting for time-of-day influences on visual processing performance.