This thesis is at the crossroads of environmental psychology and social psychology, and introduced by an epistemological reflection promoting the Complex Thought paradigm (Morin, 1977) in research, and questioning the position of environmental psychology in the scientific arena. Afterwards, we expose a work dealing with the psychosocial apprehension of transport infrastructures, a pertinent question according to populations' demands regarding landscape planning and Society's pursuit of sustainable development. Social representations theory (Moscovici, 1961), personal implication (Rouquette, 1997) and certain aspects of the Man-Environment relationship such as sense of place (Jorgensen & Stedman, 2001) and space appropriation (Vidal & Pol, 2005) were put into perspective with attitudes. Moreover, we sought to analyze different parameters that hinder or favor the acceptance of large landscape planning projects. The thesis presents several methodological developments, such as the translation of a sense of place scale (Jorgensen & Stedman, 2001), and the elaboration of a space appropriation scale. Then, it describes four case studies that were carried out in different French regions where transport infrastructures were either ongoing or recently put in effect. Every one of those studies showed the importance of the local context (economic, environmental) within social representations. We also observed that representational elements including a specific stake were the most efficient to explain attitudes. A synthesis of the four studies allowed modeling the different variables. We understood that space appropriation and personal implication also contribute to attitude construction. Discussion exposes some conditions for a good integration of transport infrastructures in the social and economic context of the studied regions, taking some critical distance with "NIMBY" conceptions. Our conclusions include proximity with the field of social geography, revealing an interesting interdisciplinary potential.
