Which systems/organisms are conscious? New tests for consciousness (‘C-tests’) are urgently needed. There is persisting uncertainty about when consciousness arises in human development, when it is lost due to neurological disorders and brain injury, and how it is distributed in nonhuman species. This need is amplified by recent and rapid developments in artificial intelligence (AI), neural organoids, and xenobot technology. Although a number of C-tests have been proposed in recent years, most are of limited use, and currently we have no (...) C-tests for many of the populations for which they are most critical. Here, we identify challenges facing any attempt to develop C-tests, propose a multidimensional classification of such tests, and identify strategies that might be used to validate them. (shrink)

A letter replying to Bayne et al. "Tests for consciousness in humans and beyond", 2024, arguing that the search for consciousness "beyond" healthy adult humans should begin with other animals.

Anosognosia for visual deficits—cases where significant visual deficits go unnoticed—challenges the view that our own conscious experiences are what we know best. We review these widespread and striking failures of awareness. Anosognosia can occur with total blindness, visual abnormalities induced by brain lesions, and eye diseases. We show that anosognosia for visual deficits is surprisingly widespread. Building on previous accounts, we introduce a framework showing how apparently disparate forms of anosognosia fit together. The central idea is that, to notice a (...) deficit, individuals need to form expectations about normal vision, compare expectations and visual input, and judge any mismatch at the metacognitive level. A failure in any of these three steps may lead to unawareness of visual deficits. (shrink)

The quality space hypothesis about conscious experience proposes that conscious sensory states are experienced in relation to other possible sensory states. For instance, the colour red is experienced as being more like orange, and less like green or blue. Recent empirical findings suggest that subjective similarity space can be explained in terms of similarities in neural activation patterns. Here, we consider how localist, workspace, and higher-order theories of consciousness can accommodate claims about the qualitative character of experience and functionally support (...) a quality space. We review existing empirical evidence for each of these positions, and highlight novel experimental tools, such as altering local activation spaces via brain stimulation or behavioural training, that can distinguish these accounts. (shrink)

Our hope and aim was to provoke debate and research on the hypothesis that conscious experiences form quality spaces [1], so we were very pleased to receive letters from Dołęga, Mentec and Cleeremans [2] and Song [3] making constructive suggestions for taking this enquiry in new directions. Our focus was on how various computational theories of consciousness can accommodate the quality space hypothesis. Dołęga et al. make the helpful observation that this should also be investigated diachronically – both developmentally, and (...) during learning. Song points to valuable work that expands our methods for investigating quality spaces. She also argues that non-conventional approaches, like Integrated Information Theory (IIT), will be needed to account for the qualitative character of consciousness. Work on IIT has been valuable in pointing to the importance of the phenomenon we grapple with in our paper – the potential interconnectedness of conscious experiences – which other theories of consciousness have tended to overlook. However, we respectfully disagree that tackling the phenomenon necessitates a non-conventional scientific approach. (shrink)