Mihrican Yaren Kaynar¹, Eren Günseli¹; ¹Sabanci University

Working memory (WM) plays a critical role in guiding attention to stimuli that match its contents. Such memory-driven attentional guidance is often studied using search tasks. Reaction time costs when the memory item is a distractor are taken as evidence for involuntary attentional guidance. However, variations in the ratio of memory to search trials across studies may confound comparisons. To address this, we manipulated the memory/(memory + search) trial ratio (25%, 50%, and 75%) to evaluate its effects on guidance. Participants were shown a color to remember and either reported the color in a memory task or the location of a diamond among disks in a search task. The distractor color either matched or differed from the memory item. Memory-guided attention was observed for all ratios. However, when the number of search trials was equated to match the minimum across conditions, the guidance effect became insignificant in the 25% memory block. The 50% ratio emerged as the most trial-efficient condition, requiring only 68 trials to detect a significant effect. Additionally, in the memory task, the mean error was smaller in 75% memory blocks than in 25% and 50% memory blocks, indicating that more frequent memory tests led to better performance. The difference in memory performance with the lack of variation in guidance between the 50% and 75% memory blocks, indirectly supports the notion that memory strength alone cannot predict attentional guidance. Together, our findings provide practical recommendations for optimizing experimental designs and offer theoretical insights into the relationship between memory strength and attentional guidance by WM.