Sequential processing of information from multiple sources

Hypotheses dealing with human sequential processing of information are derived to test an anchoring-and-adjustment mechanism of information processing and contrast-inertia models of H.J. Enhorn and R.M. Hogarth (1987). A computer-based research paradigm loosely modeled after a missile warning officer´s activity was developed for the experimental effort. Results show that the order in which pieces of evidence are submitted to the decision-makers has a critical effect on their belief, often resulting in contradictory opinions as to the presence or absence of an enemy attack. This effect, predicted by the contrast-inertia model, is especially important when mixed evidence (confirming/disconfirming) is presented to the subjects. In addition it is hypothesized that a possible framing effect causes a bias in the subjects´ beliefs, revealing an asymmetric preference for the attack hypothesis. The simple contrast-inertia model predicts the empirical data reasonably well, although its sensitivity coefficients may be complex functions of the initial anchor strength and direction, and of the number of stages in the belief-updating sequence