Abstract
Human vision is full of puzzles. Observers can grasp the essence of a scene in an instant, yet when probed for details they are at a loss. People have trouble finding their keys, yet they may be quite visible once found. How does one explain this combination of marvelous successes with quirky failures? Researchers have attempted to provide a unifying explanation in terms of mechanisms for dealing with limited capacity. In particular, a popular proposal posits limited access to higher-level processing, that a mechanism known as selective attention serially gates access to that processing, and that the gate operates early in visual processing. This account, however, has been problematic. More recently, my lab has argued that many of these puzzling phenomena confound selective attention with an alternative mechanism for dealing with limited capacity: an efficient ("compressed") encoding in peripheral vision. In this scheme, visual processing has limited bandwidth rather than limited access to higher-level processing. Recent results from my lab and others necessitate revisiting whether selective attention mechanisms operate early in visual processing, whether attention serves as a gate to further processing, and whether there exists a dichotomy between tasks that do and do not require attention. I will argue that there is little evidence for these popular concepts. Nonetheless, evidence does exist for limited capacity beyond merely limited bandwidth. Dual task performance is often worse than single task, and observers perform better when they know the task. Additional capacity limits may exist late in processing, taking the form of general limits on what tasks one can perform at a given moment. I will discuss how we might test this hypothesis.
Meeting abstract presented at VSS 2018