The Technology Acceptance Model (TAM) proposed by Davis (1986) has been tested in a number of studies, and has received considerable support. The model is parsimonious, easy to understand, and provides reasonable explanatory value under a variety of conditions. As part of a larger study, two factors (Motivation to complete the task and Social Factors) were added to the TAM model, and tested with two data samples. In the first test, Motivation and Social Factors exerted much stronger direct influences on Intentions than the TAM constructs, and the amount of variance explained in Intentions increased significantly (26 % with TAM alone; 47% with Motivation and Social Factors added). Motivation and Social Factors alone explained over 40% of the variance in Intentions. In the second test, the results were less dramatic. Differences between the samples are used to interpret the observed results. Specifically, in the context where respondents had no choice over the selection of technology, Motivation and Social Factors played a very strong part in influencing Intentions. When a choice of tools was offered, the Attitude toward using the tool exerted the strongest influence on Intentions.
Thompson, Ron, "Extending the Technology Acceptance Model with Motivation and Social Factors" (1998). AMCIS 1998 Proceedings. 254.