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The study aims to replicate the findings of Christman and Butler (2011, DOI: 10.1016/j.bandc.2011.07.003) who found difference in memory performance between consistent right handed (cRH) and mixed handed (MH) individual in relation to the level-processing effect of memory. That is, the authors report better performance in MH than cRH after semantic and intentional encoding of words, while no differences were found after judging structural features or phonemic (rhyming) properties of words. Thus, differences between the groups were found after deep but not after shallow processing of the items, resulting in a statistical interaction of handedness with memory encoding. Here, we attempt a conceptual replication of these findings in an online experiment. In contrast to the original study, we utilize a within participant (as opposed to a between design) and realize two of the for encoding condition (i.e. incidental phonemic and semantic encoding).

Face perception is largely processed in the right hemisphere. Pareidolia is the phenomenon in which we see faces in inanimate objects. The question is whether these illusionary faces are being processed like real faces, also in the right hemisphere, remains unanswered. This will be answered by a behavioral experiment using repetition priming in a visual half-field stimulation set-up.

The study builds upon Alan Paivio’s observation that the instruction to use visual imagery while encoding words improves recollection of these words compared with a situation in which the words were only encoded by reading. Seamon & Gazzaniga (1973) postulate that these two “encoding strategies” rely on different processing systems located in different hemispheres. That is, a verbal processing system, which is specialized for speech and reading, may be seen to be primarily located in the left hemisphere, while a visual-spatial processing system, which deals with spatial relations of objects, is considered to be situated in the right hemisphere. Thus, the superiority of using visual imagery could be partially explained by utilizing right hemispheric visual-spatial processing in addition to the left hemispheric verbal processing. While these findings nicely illustrate the potential relevance of hemispheric specialisation for the understanding of cognitive phenomena like the dual-coding theory. The original study suffered from several shortcomings. Small sample size (N=6) and low number of trials per condition as well as technical limitations of the then available equipment, might be taken to question the reliability of the findings. Literature search yielded only two sources which indicated a replication of the original findings. Metzger & Antes (1976) replicate the findings (at least when using pictures a probe material, Experiment II), while also having small sample size and trial number. Bersted (1983) claims replication of the strategy effect (in a footnote) but the results are not presented in the citing article, and the original poster presentation/abstract is not available. At the same time, the literature search also did not reveal any failed replication attempts. Objective of the present study is to replicate the strategy effect in a large sample and using modern equipment.

Historically, a series of influential articles has suggested a direct relationship between callosal morphology and consistency in hand preference (Witelson, 1985, doi: 10.1126/science.4023705; and 1989; doi: 10.1093/brain/112.3.799). That is, it was shown that individuals of mixed hand preference (MH) have a larger corpus callosum than consistent right-handers (cRH). Witelson interpreted these findings to indicate that a less-lateralized hemispheric organization for hand preference was associated with stronger or more efficient callosal connectivity than a strongly lateralised organization. However, a meta-analysis by Westerhausen & Papadatou-Pastou (2021; doi: 10.1101/2021.04.27.441635) was unable to confirm Witelson’s influential findings. They argue for the need for studies of brain-size difference as a confounding variable for handedness to be replicated with larger samples than in previous studies. In the present study, hand preference assessed via the Edinburgh Inventory (EHI) will be related to the size of the corpus callosum on the midsagittal surface of the brain, assessed from structural (T1-weighted) MRI images; data which is collected from the Human Connectome Project (HCP). The goal of this study is to attempt a powerful replication of Witelson's seminal finding, both considering the raw measure of midsagittal corpus callosum area as well as it's ratio to brain size. Additionally, explorative analyses are designed to test for regional differences of a potential hand preference effect (by analysing measures of callosal thickness), model the shape of the association of the degree of hand preference and callosal measures (using general-additive modelling), and explore hand-preference effects on callosal micro-architecture (based on diffusion-tensor imaging).

Functional differences between the cerebral hemispheres are a fundamental characteristic of the human brain. Researchers interested in studying these differences often infer underlying hemispheric dominance for a certain function (e.g., language) from laterality indices calculated from observed performance or brain activation measures . However, any inference from observed measures to latent (unobserved) classes has to consider the antecedent probability of class membership in the population. The present project provides a Bayesian model for valid inferences as well as scripts designed to facilitate the application of the model in research.

The OptDL project aims to establish an optimal dichotic listening paradigm for the assessment of hemispheric specialisation for language. The paradigm design aims to minimize the effect of both experimental parameters and higher cognitive functions (e.g., working-memory or cognitive-control process) on task performance to achieve reliable measures of perceptual laterality. A recent literature review (Westerhausen, 2019, Laterality, DOI: 10.1080/1357650X.2019.1598426) served as basis for the design of the paradigm.

The present study aims to examine whether the prevalence of left handedness is increased in individuals engaged in visual artistic activities. The study will determine the hand preference of artists who present their work as short video clips on the social media platform Instagram and comparing the proportion with recent meta-analytic data. Additionally, it will study whether left- as compared with right-handed artists produce art that is considered higher quality (more appealing) by the public.