Effects of Visual Anchors in Sequential Presentations of Data Visualization

Nowadays, people need to process a great deal of complex information, and make more elaborate estimations or decisions. One particular concern when handling complex information is that the first piece of information tends to bias cognition and results in estimation deviation, which is referred to as the anchoring effect. Currently, some researchers on information visualization suggest that anchoring effects can not only be found in classical numerical anchors, but in the form of visual anchors. Recent research concerning the anchoring effects in visualization investigated the existence of anchoring effects in a variety of forms and tasks of data visualization. However, these studies seem to focus only on evaluating whether users are subject to anchoring biases in a way similar to previous studies from psychology, and it is still unclear how various sequential presentations of information affect decision-making. The present study is aimed to investigate the effects of different presentations of anchors on the performance of decision-making, thus providing some support for mitigating this kind of cognitive bias.Methods To investigate, two within-subjects experiments were performed. In both experiments, participants were tasked to estimate the value of target stimuli, which presented after anchoring stimuli. In Experiment 1, A 2 (anchor value: higher vs. lower) ×2 (anchor source: experimenter-provided vs. self-generated) experimental design was adopted, to check if these factors of anchoring stimuli play a role in numerical estimation. Based on the results of Experiment 1, showing no anchoring effects under the condition of self-generated anchors, the purpose of Experiment 2 was to evaluate how different presentations of experimenter-provided anchors (with four conditions: control, clockwise, counterclockwise, and vertical) facilitate or hinder visual information processing, thus affecting decision-making. User behavior and performance in decision-making were assessed through multiple behavioral metrics, including an estimation value metrics, an estimation accuracy metric based on the correctness and a time-of-task metrics.Results Evidence of anchoring effects was presented by analyzing a variety of presentations of visual anchors. The data of Experiment 1 revealed that when responding to experimenter-provided anchors, the estimation of the target stimuli was affected by the prior anchoring stimuli, while the same results were not observed under the condition of self-generated anchors. It is shown in the Experiment 2 that these four different types of visual anchors were comparable on most metrics, and there are significant differences between three experimental groups and the control group. Then implications of our results on future work was discussed, such as the need for more physiological and electrophysiological methods to investigate underlying neural mechanisms, and raise concerns on how to alleviate anchoring biases through the design of data visualization. Conclusions To sum up, the existence of anchoring effects in data visualization was uncovered under two sources of anchors. Moreover, the effects of anchors of different presentations on decision-making was evaluated by comparing four types of visual anchors through various behavioral metrics. Our findings of this study open the potential for discovering biased visual information processing and judgements, as well as bring some insights into the design of data visualization, which might be applied to information visual analytic systems.