Provide a comprehensive examination of major theories of consciousness, including higher-order theories, global workspace theory, integrated information theory, and representationalism. Define the distinction between phenomenal consciousness (what it's like to have an experience) and access consciousness (information available for cognitive processing). Discuss the Hard Problem of consciousness and how different theories attempt to address it. Examine methodological approaches to studying consciousness, including neural correlates of consciousness (NCC) and philosophical thought experiments. Explore the relationship between consciousness and attention, memory, and other cognitive processes. Consider implications for artificial intelligence and machine consciousness.