Contributions of Different Spatial Modulations of Brightness Gradients to the Control of Visual Attention

Abstract

The targets of visual selective attention are the most informative parts of images. All new data in recent years have pointed to the importance of second-order features – spatial inhomogeneities in brightness gradients – in solving a variety of visual tasks. We addressed the problem of determining how priorities of second-order features are distributed from the point of view of attracting attention. All information from initial images of objects other than modulations of specific modalities was removed. As a result, each object was represented in three versions: images consisting of modulations of contrast, orientation, and spatial frequency. In experiment 1, images formed from modulations of different dimensionalities but with the same spatial frequency competed for attention. In experiment 2, modulations of the same dimensionality but different frequencies were used. The direction of the subject’s attention was evaluated by recording eye movements. The first saccade after stimulus onset was assessed. The observations showed that in the object orientation discrimination task using pairs of sequential stimuli, images formed from modulations of contrast and orientation of lower spatial frequency had a significant advantage in competing for attention. This result is explained by the notion that in competing for attention, areas of images with greater amplitude of brightness gradient modulation had the advantage in competing for attention.