ABSTRACT
In order to decide whether nonhuman animals are conscious, it is helpful to begin with an empirically motivated account of the precise conditions under which consciousness arises in human beings. Mammals also face the same challenge as humans when it comes to perception: converting local cells at the sensory periphery into representations of complex properties and objects. What if people move beyond mammals? A surprising range of taxa show evidence for hierarchically organized senses. This is true of cephalopods, birds, and insects. Mammals also show similar capacities for working memory. All mammals can retain information for brief intervals, after a stimulus has been removed. Bird working memory has been studied using some of the same tasks that are used in mammals, including delayed matching to samples. Gastropods probably lack consciousness, given the simplicity of their nervous systems, but cephalopods are good candidates.
