The mathematical theory of a contrario detection formalizes the non-accidentalness principle and attempts to predict ideal perception thresholds. Thus, it is natural to reconsider from a computational perspective, classic and new psychophysical experiments evaluating the human perception performance. To this aim, we chose the psychophysical experiments by Wagemans et al. where subjects are presented with Gabor-rendered outlines of real world objects. In these experiments, orientation jitter was added to the elements with the aim of determining its effect on human object detection performance. Using the a contrario theory, the human detection thresholds can be compared rationally to the algorithmic ones. To allow a broader experimentation, we built an online web facility where users can perform object detection experiments, and compare their detection curves to the ones predicted analytically by the computational model.