René Westerhausen

Tag: laterality

  • “Use Your Nice Hand!” – The Retraining of Left-Handers in 20th-Century Germany

    “Use Your Nice Hand!” – The Retraining of Left-Handers in 20th-Century Germany

    Based on historic documents and recently published survey data, the post explores the history of the retraining of left-handers in Germany during the 20th century.

    Whenever I read about the retraining of left-handers, I am transported back to this one episode from my childhood. Sitting at the kitchen table at my grandparents’ house, I was busying myself by with a colouring book. I must have been only about three years old, but I remember how my grandmother joined me. Sitting down next to me in her light blue apron, she gently instructed me with a “use your nice hand!”, as I, according to her opinion, was holding the crayons in the wrong, left hand [1].

    There was no explanation for why the right hand was deemed “nicer”, and had I asked her for a reason, she likely would have shrugged. For her generation, born and raised in rural Germany in the 1920s, it was just obvious that writing or drawing had to be done with the right hand.

    The practise of training left-handed children to write with their right-hand, arguably, has a long tradition in Germany [2], like it has in most, if not all, other countries. Caregivers at home or teachers at school would instruct children, sometimes even using rather ungentle measures, to use their right hand. The personal accounts of many “first-hand victims” of this strange practise can easily be found in the various online forums dedicated to the topic [3]. And whenever you find a SoMe post concerning left handedness, you can be almost certain to also find comments below it that report such retraining experience. Yet, as the saying goes, times change, and this practice – while not complete overcome – has gone increasingly out of fashion. The continuously rising number of left-handers across the globe can be seen as evidence for this development [4].

    While handedness retraining in Germany is well-documented by countless anecdotal reports, it is much more difficult to find reliable information on how frequent it actual was, or until when exactly it was systematically practised. A bit of “snooping” through publicly available political and pedagogical archives [5] reveals that handedness – or its retraining – only very rarely appears as a concern in these texts. And were it does, it is promoting tolerance of left-handed writing rather than the opposite. I was not able to find a single serious document instructing pedagogues to retrain their left-handed students.

    For example, already in 1920, the Minster for Education of Prussia, Konrad Haenisch, explicitly advised teachers in the states’ schools to allow left-handed writing [6]. He ordered that, after carefully confirming a student’s left handedness, it should be left up to the student’s own choice whether they prefer to write with their left or right hand. Or, to quote the German original:

    “[Es] ist den Schülern freizustellen, ob sie beim Schreiben von der linken oder rechten Hand Gebrauch machen wollen.”

    Such a progressive policy in the by far largest federal state of the young German republic could be predicted to have a huge impact, potentially leading to a significant increase in left-handed writers in subsequent generations. However, the available data does not really support this expectation. Instead, it did not have any measurable immediate effect.

    This conclusion is based on a recent study on this topic [7], which analysed data from a representative survey on the economic situation of German households, incorporating handedness information from approximately 13,000 men and women born between 1920 and 1997. Recognising that overall handedness and writing hand are not necessarily the same, the designers of the survey had included the two simple handedness questions: “Are you a natural right- or left-hander?” and “With which hand do you actually write?“

    The graph below shows how the participants of the study answered these questions by featuring two key plots. The first, represented by the bold solid line at the top, shows the proportion of participants from each birth cohort who identify as “natural left-handers.” The second – the bold dashed line – shows the proportion of participants who actually write with their left hand.

    Graph illustrating the data as described in the the text.
    Figure adapted from Guber (2019) [6]. The graph shows the proportion of individuals indicating that they are natural left-handers (bold solid curve) and left-handed writers (dashed solid). The thinner dashed lines represent “error margins” for the fitting of the curves into the available data. The closer they are to the fitted curve, the more confident one can be in the fitted value.

    If there had been no retraining at all, all natural left-handers would also write with their left hand. That is, we would expect the two plots to overlap almost entirely. As can be seen, however, this is not the case for most of the cohorts. There is a significant gap between the two lines, which persists until the 1990s. So, it appears that until then, handedness retraining was practised in Germany, if not nationwide so at least in a few classrooms or around some kitchen tables.

    The proportion of left-handed writers did, however, steadily increase across the generations, with a noticeable acceleration starting with those cohorts born from around the 1960s. As a result, the “retraining gap” between the two curves was successively closing. Eyeballing the graph, one can also guess that from the 1970s cohorts onwards less than 50% of the left-handers experienced retraining attempts of lasting “success”, while this number seems below 25% for those born in the 1980s.

    Interesting is also what this graph does not show. There are no noticeable dips or bumps in the curve representing the proportion of left-handed writers. For example, the aforementioned 1920 directive by the Prussian Ministry of Education – allowing students to write with their left hand – did not result in the expected increase in left-handed writing rates. Also, other historical changes in German government with their dramatic shifts in political ideology, seem not have left a noticeable mark in these curves.

    Taken together, it has taken Germany at least 70 years – from the first federal state endorsing left-handed writing in schools to a virtually stop of the practise of retraining in the 1990s. It was a slow but steady societal shift toward greater tolerance of left-handedness rather than a sudden jump caused by political decisions. Of note, the members of Gen Z might well be the first Germans not to learn from others which of their two hands is supposed to be the “nicer” one.

    [1] I am not sure what effect this and similar episodes had on my own hand preference. Likely none, as I am strongly right handed today, and I am quite certain that I also without this early intervention by my grandmother would have turned out be a boring right-hander.

    [2] see also evidence from the 19th century, shown here: https://westerhausen.dk/retraining-of-left-handers-evidence-from-a-mid-19th-century-caricature/

    [3] Take, for example, the subreddit on handedness: https://www.reddit.com/r/handedness/

    [4] McManus, I. C., Moore, J., Freegard, M., & Rawles, R. (2010). Science in the Making: Right Hand, Left Hand. III: Estimating historical rates of left-handedness. Laterality, 15(1-2), 186-208. https://doi.org/10.1080/13576500802565313

    [5] one excellent source is https://scripta.bbf.dipf.de/viewer/index/

    [6] It is a directive targeted at regional school administrations; published on page 322-323 in: Ministerium für Wissenschaft, Kunst und Volksbildung (1920). Zentralblatt für die gesamte Unterrichtsverwaltung in Preußen. Weidmannsche Buchhandlung, Berlin

    [7] Guber, R. (2019). Making it right? Social norms, handwriting and human capital. Labour Economics, 56, 44-57. https://doi.org/10.1016/j.labeco.2018.11.005

  • What the Hell is Dichotic Listening? A Beginner’s Guide With Useful Links.

    What the Hell is Dichotic Listening? A Beginner’s Guide With Useful Links.

    The article provides a brief introduction to dichotic listening with helpful links for interested researchers and curious others.

    Dichotic listening is a classical test used by neuropsychologists to determine a person’s brain lateralisation for language functions. Its main appeal is that it is suitable in almost all settings as it is accessible to participants of all ages and abilities. The used speech stimuli are very simple and the instructions are easily understood and followed. Yet, despite its simplicity, the paradigm is a powerful tool to learn about the brain’s functional organisation.

    At the core of the paradigm is the dichotic presentation: two sounds are presented simultaneously via headphones (as shown in the cartoon above), with one sound being played to the left ear and the other one to the right ear.

    Various stimulus sounds have been used by researchers. My favourite version uses short consonant-vowel syllables, like Ka and Pa. These syllables are acoustically very similar to each other, and participants often believe they hear only one stimulus, even though two different stimuli are presented. So, when asked to report what they heard, participants typically just report one of the two stimuli.

    Importantly, however, the reported stimulus is more often the stimulus played to the right ear than the one played to the left ear. This phenomenon is called the right-ear advantage and is linked to how, or better, where the brain typically processes speech and language.

    In most people, speech processing is primarily a function of the left hemisphere, while only in small minority of the population (about 15%) the opposite is the case. We know this from clinical observations, where identifying the location of language processing is essential; for example, when planning brain surgery. Here, the location of the brain’s language centers has traditionally been determined by briefly anaesthetising one hemisphere at a time. If the anaesthesia prevents the patient from speaking, the “sedated” hemisphere is obviously the one responsible for speech processing.

    Intriguingly, studies in the 1960s [1], that were conducted on these patients, showed that those with left-hemispheric dominance for language also prefer to report stimuli from the right ear when tested with dichotic listening. Reversely, those with dominance of the right hemisphere, preferred the left-ear stimuli. The hemisphere opposite to the preferred ear, was the one dominant for language. That is, the ear preference shown in dichotic listening was a pretty good predictor of which hemisphere was processing language in these patients.

    But, how could this oddly “crossed” association be explained? One influential theoretical model [2] explains this by pointing out that each ear is predominantly connected to the opposite hemisphere. So, if the relevant language centers are, as typically is the case, located in the left hemisphere, the stimulus from the right ear will be the first to get access to language processing. This “first” stimulus will consequently dominante the subjective perception, which leads to the right-ear advantage. For a comprehensive discussion of this model and competing theoretical explanations can be found in an article published a few years ago [3] (which can be found here).

    Today, dichotic‑listening paradigms are widely used to determine which hemisphere supports language processing. However, over the six decades since the paradigm was first introduced, numerous versions of the paradigm have emerged, and not all are equally suitable for this purpose. Design choices – such as the type of stimuli, the number of trials, or the instructions given – can substantially influence the outcome. At the same time, the extensive body of evidence that is available can be used to inform on how to design an optimal paradigm. A guide to support researchers in designing their own dichotic‑listening protocols has recently been published [4](and can be found here).

    Naturally, we also designed an own optimal version of a dichotic-listening paradigm following these guidelines [5] (link). The empirical testing of the paradigm looked promising suggesting an excellent reliability. The paradigm (EPrime version) and stimulus material can be downloaded from the accompanying OSF page (here). It also includes some additional recommendation concerning the testing equipment as well as the data collected when first testing the new paradigm.

    [1] Kimura, D. (1961). Cerebral dominance and the perception of verbal stimuli”. Canadian Journal of Psychology.,15(3), 166–171. https://psycnet.apa.org/doi/10.1037/h0083219

    [2] Kimura, D. (1967). Functional Asymmetry of the Brain in Dichotic Listening. Cortex, 3 (2), 163–178. https://doi.org/10.1016/S0010-9452(67)80010-8

    [3] Westerhausen, R. & Kompus, K. (2018). How to get a left-ear advantage: A technical review of assessing brain asymmetry with dichotic listening. Scandinavian Journal of Psychology, 59 (1): 66–73. https://doi.org/10.1111/sjop.12408

    [4] Westerhausen, R. (2019). A primer on dichotic listening as a paradigm for the assessment of hemispheric asymmetry. Laterality, 24(6), 740–71. https://doi.org/10.1080/1357650X.2019.1598426

    [5] Westerhausen, R., & Samuelsen, F. (2020). An optimal dichotic-listening paradigm for the assessment of hemispheric dominance for speech processing. PLoS ONE, 15(6), e0234665. https://doi.org/10.1371/journal.pone.0234665

  • Retraining of left handers: evidence from 19th century caricature

    Retraining of left handers: evidence from 19th century caricature

    A caricature from 1856 reveals that the retraining of left handers was a recognised practise in 19th‑century Germany.

    On one of my virtual excursions into the excellent digital historical library of the University of Heidelberg [1], I came across the weekly Bavarian-German magazine called Fliegende Blätter, so, Flying Pages. Founded in 1844, the magazine ran for more than 100 years, and was widely appreciated for its sure‑footed, satirical portrayal of the German bourgeoisie.

    The caricature above, which I found in a 1856 issue [2], nicely reflects this sentiment. It is drawn by the physician and artist Ferdinand Schröder and entitled Das Mutterauge, the eye of a mother. And with this eye, the mother observes how her dear little boy Emil is about to hit his (likely) nanny with a stick. The mother does not like what she sees and, as every good mother would, decides to intervene, although for slightly different reason than expected.

    “Aber lieber Emil, wie oft soll ich es Dir denn sagen?!“, she exclaims, “Schlägst Du schon wieder mit der linken Hand!!“

    Translated:

    “But dear Emil, how often do I have to tell you?! Again you are hitting with your left hand!!“

    The dear son is using the wrong hand! He should rather hit the poor nanny with the stick in his right hand! This unexpected reason for the intervention is obviously meant as a social criticism. The servants do not really matter to those wealthy people. The seemingly trivial matter of the son’s hand preference is more important than the well being of the nanny. A moral bankruptcy.

    The caricature does also show, however, that the retraining of left handers — the forced conversion of children to use their right instead of their preferred left hand — was “a thing” in mid-19th century Germany. Using it as a topic for mocking the rich people assumes that the reader is familiar with the concept. And indeed, it can be expected that retraining was quite frequently done at this time, and not only in Germany.

    Today, we know that left handedness is at least partly determined by genetic factors [3], letting it appear barbaric to retrain a child against its innate preference. In the 19th century, however, it was usually assumed that handedness is just a matter of education and upbringing. And a person brought up well, so the common opinion, was to be right handed. A rule of proper etiquette. Real or want-to-be bourgeoisie parents had to train their children to write with their right hands. Raising a left-handed child, or being openly left handed, would have been a social embarrassment.

    The retraining has luckily increasingly gone out of fashion, and left-handed members of Gen Z living in Europe or North-America will likely not have suffered through it. But many left handers of earlier generations[4] or of different cultural origin [5] have certainly experienced retraining. So, unfortunately, there are still too many out there with a first-hand experience of retraining.

    [1] Heidelberg historic literature – digitized;

    [2] source of caricature: https://doi.org/10.11588/diglit.2122#0021

    [3] review by Paracchini, S. (2021); https://doi.org/10.3390/sym13101792

    [4] example from Germany: Guber, R. (2019). https://doi.org/10.1016/j.labeco.2018.11.005

    [5] example from Africa: Alhassan, A.B. (2018).http://dx.doi.org/10.19080/GJAA.2018.07.555713