How to operationalise consciousness

Objective: To review the way consciousness is operationalised in contemporary research, discuss strengths and weaknesses of current approaches and propose new measures. Method: We first reviewed the literature pertaining to the phenomenal character of visual and self-consciousness as well as awareness of visual stimuli. We also reviewed more problematic cases of dreams and animal consciousness, specifically that of octopuses. Results: Despite controversies, work in visual and self-consciousness is highly developed and there are notable successes. Cases where experiences are not induced, such as dreams, and where no verbal report is possible, such as when we study purported experiences of octopuses, are more challenging. It is difficult to be confident about the reliability and validity of operationalisations of dreams. Although this is a general concern about the measuring consciousness, it is not a sufficiently severe concern to completely undermine the work reviewed on vision and self-consciousness. It is more difficult to see how the good work on human psychology can be applied to non-human animals, especially those with radically different nervous systems, such as octopuses. Given the limitations of report-based operationalisations of consciousness, it is desirable to develop non-report-based measures, particularly for phenomenal qualities. We examine a number of possibilities and offer two possible approaches of varying degrees of practicality, the first based on combining quality space descriptions of phenomenal qualities and the notion of a “neural activation space” inherited from connectionist A.I., the second being a novel match to target approach. Conclusion: Consciousness is a multi-faceted phenomenon and requires a variety of operationalisations to be studied.