The planning fallacy: Inside/outside views
Description
This study provides empirical support for Kahneman and Tversky's (1979) claim that people rely far more on singular information (inside view) than on distributional information (outside view) when estimating the completion time of a task. This claim, which describes the cognitive process of Kahneman and Tversky's 'planning fallacy' theory, is tested by analyzing participants' tendencies to prefer information belonging to the inside or the outside view of the task presented to them as they prepared the task's planning schedule. During the experiment, some participants were biased toward the inside view and others to the outside view of the task to study the effects that this manipulation may have in participants' information choices, time estimates, and degree of confidence in their estimates. Participants' individual differences in need for cognition (NC), positive affectivity (PA), and negative affectivity (NA), were related with participants' information choices, times estimates, and degree of confidence in their estimates. Although, because of the hypothetical nature of the scenario presented to them, the accuracy of participants' predictions lies outside the scope of investigation, the study does confirm the basic cognitive process underlying the initial stages of planning, and thus of the cognitive process of the planning fallacy. Overall, experimental participants tended to use more information from the inside than from the outside view of the task. Contrary to expectation, participants who assigned more importance to inside factors estimated longer completion times, and participants who gave greater weight to outside factors showed higher degrees of confidence in their estimates. Participants high in need for cognition tended to show lower degrees of confidence in their time estimates, and participants high in negative affectivity gave greater importance to outside issues and showed higher degrees of confidence. Findings suggest that the importance given to the type of information could have a moderating effect between participants' negative affectivity and their degree of confidence in their time estimates. It was found that participants' manipulation toward the inside or outside view of the task did not have any effect their information choices, time estimates, and degree of confidence