 One further point worth noting is that structural models of consciousness are usually justified in terms of phenomenological or introspective observations — i.e. observations about the nature of consciousness as it is experienced by the subject. Though the use of such first person methods is now and has been controversial in psychology and philosophy throughout the 20th and 21st century, there seems to now be a broad acknowledgement that it has an indispensable role in the scientific study of consciousness, as many authors who have published recent scientific theories of consciousness include some appeal to phenomenological premises in justifying their views (e.g. Seth, Edelman and Baars 2005; Merker 2005; Tononi 2008; Cabanac et al. 2009).