Pigeons simultaneously attend to static and dynamic features of complex displays

Abstract

The simultaneous processing and attention to temporally dynamic and static features remains an open and important question in theories of avian visual cognition. Here, four pigeons (Columba livia) learned to discriminate complex displays involving concurrently available static and dynamic features. These displays consisted of 20 elements built from combinations of two, binary-valued, static visual dimensions: red vs. green element color, large vs. small element size; and two binary-valued dynamic dimensions; fast vs slow element motion, right vs up motion direction. One combination of these four features was reinforced on a VI schedule. The remaining 15 combinations of element color, size, speed and direction were never reinforced. During acquisition, all four dimensions were simultaneously discriminated. Varying the number of elements revealed that a single element was sufficient to support discrimination of all four dimensions. The pigeons agreed on the relative discriminability of stimuli within and across the different dimensions, with the difference in motion direction being the hardest for all birds. Redundant facilitation suggested rapid, perhaps parallel, processing of both dynamic and static features. No attentional trade-offs between dynamic or static dimensions were observed. These results agree with theories of avian vision employing the notion of multiple independent channels for different types of information.