While interactivity is regarded as a distinguishing characteristic of computer technology, the explanation on its impact remains in its infancy. The present research investigates what it means to provide a more (or less) interactive computer interface design by attempting to uncover its cognitive influences on the user's expectation of outcome and decision confidence. Drawing on theories of control, we proposed seven hypotheses. The results of the three experimental surveys lent support to the hypotheses that Perceived Interactivity (PI) manipulated by three technological interactivity features--modality, source, and message-interactivity--is positively associated with Outcome Expectation (OE) and Decision Confidence (DC). Our analyses further revealed that these PI-OE and PI-DC links were fully mediated by Cognitive Absorption (CA). Amongst the five factors that constitute CA, it was the "perception of Control" that played the determining role in the identified mediation processes. Although both DC and OE were positively influenced by PI (and the perception of control associated with it), unlike our hypothesis (H7), the DC-OE link was not significant. PI's impact on OE was a direct consequence of the Illusion of Control elicited by the skill-cue associated with user involvement and choices inherent in the interactive process. While PI also positively affected DC, this impact was less predictable as DC reflects the combined result of many factors: sense of control over the information flow, rationale construction, direct experience effect and illusion of validity. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]