A growing body of evidence is reviewed showing that degree of handedness (consistent versus inconsistent) is a more powerful and appropriate way to classify handedness than the traditional one based on direction (right versus left). Experimental studies from the domains of episodic memory retrieval, belief updating/cognitive flexibility, risk perception, and more are described. These results suggest that inconsistent handedness is associated with increased interhemispheric interaction and increased access to processes localized to the right cerebral hemisphere.

The present study investigated variables potentially associated with a lack of concern about COVID-19 and belief in the conspiracy theory that China is responsible for the virus. In particular, the study looked at Authoritarianism, Conspiracy Beliefs, gender, and consistency of handedness as predictors of nine Likert-type items gauging attitudes, behavior, and beliefs regarding the virus. Initial analyses showed that Authoritarianism predicted less concern about the impact of the virus on health, less mask wearing, and a stronger belief in China’s responsibility for the illness. Conspiracy Beliefs were associated with a stronger belief in China’s responsibility. Women expressed greater degrees of concern about their own and others’ health and about the financial wellbeing of others. In order to reduce the number of dimensions, and thus the number of tests that could yield a type one error, the nine items were then submitted to a principal components analysis which yielded a “Concern about COVID” factor and a “Blame for China” factor. Authoritarianism is generally associated with less concern about the virus. In addition, men showed less concern about the virus overall than women. Both Authoritarianism and Conspiracy Beliefs accounted for unique variance in blame on China for the virus.

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Past research using handedness as a proxy for functional access to the right hemisphere demonstrates that individuals who are mixed/inconsistently handed outperform strong/consistently handed individuals when performing episodic recall tasks. However, research has generally been restricted to stimuli presented in a list format. In the present paper, we present two studies in which participants were presented with paragraph-level material and then asked to recall material from the passages. The first study was based on a classic study looking at retroactive interference with prose materials. The second was modelled on a classic experiment looking at perspective taking and the content of memory. In both studies, the classic effects were replicated and the general finding that mixed/inconsistent-handers outperform strong/consistent-handers was replicated. This suggests that considering degree of handedness may be an empirically useful means of reducing error variance in paradigms looking at memory for prose level material.

A classification of humans into a near 50-50 split of inconsistent-versus consistent-handers is more consistent with behavioral, genetic, and evolutionary considerations than the traditional classification of 90 % right-handed and 10 % left-handed. In addition, inconsistent-versus consistenthandedness is associated with more flexible versus rigid cognitive styles, respectively, and it is argued that this heterogeneity of cognitive styles provided by the inconsistent-handed "willows" versus the consistent-handed "oaks" gives human society a beneficial blend of adaptive flexibility and stability.