When engaging in data transactions, it has consistently been observed that individuals' behaviour does not correspond with individuals' theoretically stated preferences about privacy and the importance of personal data. This paper considers this 'paradox'. First, through an analysis of selected surveys, we elaborate a picture of how the public perceives the data environment and their interaction with it. We find that, whilst the public places significant weight on the values of privacy and data protection and has a formal understanding of the features of the data environment, there is a significant knowledge deficit relating to the specifics of data flows and processing. Although the public felt that they were being forced into engaging in an ever increasing number of data transactions, they lacked the clarity and understanding to evaluate the significance of these transactions either at the individual or social level. We then consider how these findings relate to specific transactions involving personal data transfer. Acquisti and Grossklags theorise that decision making may be unbalanced by limited information, bounded rationality issues, psychological distortions and ideology and personal attitudes. Using the findings from our selected survey analysis, we add substance to these claims. The lack of understanding of the data environment coupled with the necessity to act in this environment accounts for impacts on each limiting factor and reduces the ability for the individual to 'rationally' balance each transaction. Awareness of issues (and the importance allocated to personal data) on an abstract scale does not translate to the apparently corresponding action in concrete situations.