Large-scale examination of the benefit and cost of spatial attention and their individual variability

Spatial attention-the ability to prioritize relevant regions in the environment-is crucial for human cognition and has accordingly been studied extensively. However, large population samples have seldom been used, leaving inter-individual variability largely unexamined. This is especially true for the distinction between attentional benefit (improved performance when attending the correct location) and cost (impaired performance when attending the wrong location), which is critical for distinguishing facilitatory from inhibitory mechanisms. This distinction is sometimes avoided because it requires a baseline condition and choosing a truly neutral cue for this condition can be challenging. Here, we recruited a sizable participant pool (N = 662) across four experiments. We combined an acuity task with valid, invalid, and neutral pre-cues of different types and analyzed the averaged attentional benefits and costs and their inter-individual variability. We found robust attentional benefits, but attentional costs depended on inter-stimulus distance, highlighting the importance of employing neutral cues. Similar patterns of attentional benefit and cost emerged for the experiments that used different types of neutral cues. Moreover, when neutral cues were compared directly no difference in performance was found. These findings suggest that the neutral cue's characteristics are not critical. Hierarchical Bayesian analyses revealed true qualitative individual differences; while most individuals showed effects in the expected direction, some exhibited effects in the opposite direction. This finding emphasizes the complexity of attentional allocation, suggesting that a comprehensive account of spatial attention needs to incorporate several underlying mechanisms including factors that may result in attentional effects in the opposite direction.