The time course of the first decision in scene viewing: Perceptual and semantic contributions to initial scene processing.

Effective behavior requires that we respond to the environment rapidly and appropriately. Our visual system can extract a range of information from scenes within tens of milliseconds. The timing of the first eye movement, therefore, may reveal key aspects of the mechanisms underlying rapid extraction and utilization of information during this essential, initial processing, yet we lack theoretical understanding of these mechanisms. Across several data sets, this study shows differences in the timing of the first saccade. Modeling individual data sets, we tested whether the decision mechanism for the first saccade is different from that for subsequent saccades. We found that when viewing started from the scene center, the time course of the first saccadic decision was influenced by low-level features in peripheral vision. However, when viewing started noncentrally, and was aligned more predictably with informative content, low- and high-level information in both foveal and peripheral vision was accumulated and evaluated in the decision process. These findings suggest a common mechanism for initial and later processing of the scene, but with priorities for weighting the input that depend on expectations about foveal content at scene onset. This study extends existing theoretical frameworks for decision making in scene viewing to encompass initial scene processing and expectation-based flexibility in information weighting. (PsycInfo Database Record (c) 2025 APA, all rights reserved).