Attentional Spread during One-shot Visual Perception of Multiple Objects

The capacity of fine vision of individual object is limited by the “bottleneck” of attention and working memory. Still, at every moment we see large collections of objects. What exactly happens to individual representations when the observer attempts to distribute attention between multiple objects? One view is that a fixed number of objects are represented with good fidelity while others are represented with poor fidelity. Another theory is that attention is evenly distributed among all objects but fidelity decreases as set size grows. Here we directly tested in how the capacity and fidelity change with set size. Our results are generally consistent with the idea of fixed capacity focal attention: when observers perceive multiple objects during a short time, they focus attention on a limited sample of items represented with approximately the same fidelity, rather than evenly distribute it among all of the objects.