On the network-based emulation of human visual search

Abstract

We describe the design of a computer emulator of human visual search. The emulator mechanism is eventually meant to support ergonomic assessment of the effect of display structure and protocol on search performance. As regards target identification and localization, it mimics a number of characteristics of human search performance under experimental conditions of target/nontarget separability and stimulus complexity. Performance aspects accounted for, include: feature space adaptation, attention orienting and cueing, processing stages in early vision, data-limited and resource-limited processing, automatic and controlled processing, search asymmetry and illusory conjunction, spatial and temporal masking, and disengaged/engaged attentional states. Feature space adaptation results from the (supervised) training for optimized target/nontarget discrimination. In the actual emulation experiments there are three processing modes: Global identity processing, Sectoral-directional emphasis of identity processing, and Local identity processing. The chosen network approach (which was motivated on information theoretical grounds) proved instrumental in our quest for a set of ‘humanoid’ system behaviors that would function as a descriptive framework of visual search performance. Within the task constraints imposed on the human perception and action in the usual experimental setting the emulator may serve as a means to study subject training aspects, input data-limitation (e.g., low input excitation or short exposure time), memory data limitation (e.g., search asymmetries, illusory conjunction), and resource-limitation (e.g., display size, lateral marking), and the effects of self-paced or externally paced shifts of attention.