That said, these stable levels of bias within individuals are possible to change. Participants in experiments who watched training videos and played debiasing games showed medium to large reductions both immediately and up to three months later in the extent to which they exhibited susceptibility to six cognitive biases: anchoring, bias blind spot, confirmation bias, fundamental attribution error, projection bias, and representativeness. Individual differences in cognitive bias have also been linked to varying levels of cognitive abilities and functions. The Cognitive Reflection Test (CRT) has been used to help understand the connection between cognitive biases and cognitive ability. There have been inconclusive results when using the Cognitive Reflection Test to understand ability. However, there does seem to be a correlation; those who gain a higher score on the Cognitive Reflection Test, have higher cognitive ability and rational-thinking skills. This in turn helps predict the performance on cognitive bias and heuristic tests. Those with higher CRT scores tend to be able to answer more correctly on different heuristic and cognitive bias tests and tasks. Age is another individual difference that has an effect on one's ability to be susceptible to cognitive bias. Older individuals tend to be more susceptible to cognitive biases and have less cognitive flexibility. However, older individuals were able to decrease their susceptibility to cognitive biases throughout ongoing trials. These experiments had both young and older adults complete a framing task. Younger adults had more cognitive flexibility than older adults. Cognitive flexibility is linked to helping overcome preexisting biases. Criticism Criticism against theories of cognitive biases is usually founded in the fact that both sides of a debate often claim the other's thoughts to be subject to human nature and the result of cognitive bias, while claiming their own point of view to be above the cognitive bias and the correct way to "overcome" the issue. This rift ties to a more fundamental issue that stems from a lack of consensus in the field, thereby creating arguments that can be non-falsifiably used to validate any contradicting viewpoint. Gerd Gigerenzer is one of the main opponents to cognitive biases and heuristics. Gigerenzer believes that cognitive biases are not biases, but rules of thumb, or as he would put it "gut feelings" that can actually help us make accurate decisions in our lives. His view shines a much more positive light on cognitive biases than many other researchers. Many view