1. See review in Pylyshyn Z.W. (2002) ‘Mental imagery: In search of a theory’, Behavioral and Brain Sciences, 25, 157–237.
2. Fodor, J. (1994) ‘Concepts: A potboiler’, Cognition, 50, p. 95.
3. Harnad, Stevan (2005) ‘To cognize is to categorize: Cognition is categorisation’, in Lefebvre, C. and Cohen, H. (eds) Handbook of Categorization in Cognitive Science, New York: Elsevier.
4. Giurfa, M. (2009) Animal Cognition: Nonelemental Learning Beyond Simple Conditioning, Cold Spring Harbor: Cold Spring Harbor Laboratory Press. p. 281.
5. Hebb, D.O. (1949) The Organization of Behavior, New York: Wiley. p. 14.