Delusion-like beliefs and data quality: Are classic cognitive biases artefacts of carelessness?

There is widespread agreement that delusions in clinical populations and delusion-like beliefs in the general population are, in part, caused by cognitive biases. Much of the evidence comes from two influential tasks: the Beads Task and the Bias Against Disconfirmatory Evidence (BADE) Task. However, research using these tasks has been hampered by conceptual and empirical inconsistencies. In an online study, we examined relationships between delusion-like beliefs in the general population and cognitive biases associated with these tasks. Our study had four key strengths: a new animated Beads Task designed to reduce task miscomprehension, several data-quality checks to identify careless responders, a large sample (n = 1,002), and a pre-registered analysis plan. When analyzing the full sample, our results replicated classic relationships between cognitive biases and delusion-like beliefs. However, when we removed 82 careless participants from the analyses (8.2% of the sample) we found that many of these relationships were severely diminished and, in some cases, eliminated outright. These results suggest that some (but not all) seemingly well-established relationships between cognitive biases and delusion-like beliefs might be artifacts of careless responding.