Some animals can communicate via color patches on their skin. For example, everybody knows what is going on with you when you suddenly blush. Just kidding. Of course, I don’t talk about humans. The paper of the day is about the common chameleon. In color communication (which you also find in insects, birds,…) there are two different strategies: I) adapt your color to different situations, II) have a color pattern which you just show in specific situations and otherwise hide/conceal it. Chameleon colors belong to the first type: they change them according to the season, background and social signaling, instead of concealing them. But what about the lateral white stripes? (see figure) Tammy Keren-Rotem, et al. (2018) analyzed the appearance of white spots in chameleons in different situations (season and social context). They showed that male and female chameleons consistently display the white badges, while body colors and patterns change. However, while mating, the white badges are concealed. What is the meaning of this? It could be that the white badges are used to identify individuals, as they are stable in shape within individuals but vary between individuals. It could also be, that the fact, that the white badges are proportional to the total body size, allows conclusions about individual quality, fighting ability and/or dominance. The authors explain their findings by the multitasking hypothesis: The information transfer in one color pattern is constrained by the presence of another color pattern. That means, when I would be a chameleon, the white stripes may help to show my quality. However, my lack of multitasking ability restricts my communication when I use stripes and color and I can not clearly transmit my mating intentions. Therefore, I get rid of the white stripes when I find a nice mate. That is the idea. Proof is still needed.
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The magic of a break. For a short time put your work aside and do something else. At least while struggling with verbal learning tasks, such breaks should be helpful and improve your memory. The “spacing effect” as it is called in memory literature, refers to the fact that spatial learning (with temporal lags between the learning session) results in greater retention accuracy and less forgetting compared to massed learning (no lags). There are many different theories why “spatial learning” works. Maybe it works because that the cues which are present in the different learning session variate (a different environment, a different mood) and improve learning. And/or it is just this cycle between forgetting (in the lags) and recall (during the session) which strength the memory. Whatever it is: does it work for any type of learning? Most experiments focus on verbal learning. For motor learning the studies show variating results. Melody Wiseheart (great name by the way) and colleagues analysed if there is a spacing effect while learning to play the piano. They asked students with varying music education to perform two tasks: One focuses on the “translation” from music sheets to the right finger movement on the piano keyboard, the other on the auditory feedback to reproduce a certain melody with right volume and rhythm. Interestingly, massed learning and spatial learning strategy showed both the same learning performance in both tests. Maybe the time lags (max 15min) were to short. But at least it shows, that the spacing effect may vary with the learning task. “Lack of spacing effects during piano learning”
Wiseheart M, D’Souza AA, Chae J (2017) PLoS ONE 12(8): e0182986. The todays paper of the day is about stuttering. When I googled stuttering I found a funny quote: “Stuttering is Ok. Because what I say is worth repeating”. This quote highlights already the most prominent feature of stuttering: the involuntary repetitions of sounds and words which disturb the fluency of speech. Moreover, involuntary prolongations of sounds and involuntary silent pauses in which the person is unable to say anything, are also characteristics of stuttering. Sometimes people stutter in uncomfortable stressful situations, sometimes the stuttering is a persistant disease (also called chronic perseverative stuttering - CPS). The latter is the focus of the paper of Jolanta Góral-Półrola et al. (2015). The neurodevelopmental hypothesis of fluency of speech “suggests that the main symptoms in stuttering disorders are the result of integrated genetic, developmental, neurological, and social factors.” Based on this hypothesis, Góral-Półrola et al. (2015) looked at the gene expression of a 26 years old CPS patient. The focus was on stress related genes. Interestingly, “the expression of almost all tested genes, with the exception of IL1, in patient’s leukocytes were lower than in the control group.” This either means a lower stress load of this patient or insufficient stress response and protection of the cells. Of course, a single patient is not enough for significant study results, but having in mind that the most of us were already in a stressfull situation in which they started stutering, it seems quite logical that chronic stuttering may be connected to an decreased stress tolerance due to low stress gene expression. Just as remark: "Changes in gene expression associated with cell stress in the patient with chronic persevarative stuttering"
Góral-Półrola et al. (2015). Leeches are fascinating animals. They can be found everywhere, from ponds to streams, from polar seas to desert oases. Many of the about 300 species of leeches feed on small invertebrates, only some species are parasitic blood suckers. The leech’s spittle does not only contain enzymes which prevent blood clotting but also an anesthetic. So the host is not aware of the attack by the blade-like jaws or secreted enzymes that digest a hole through the skin. It is no accident that the most famous leech species is called Hirudo medicinalis. Leeches have a long tradition in medical treatment. Before using it for treatment, the leech needs to be washed and the gut content needs to be squeezed, because leeches just “attack” when their gut is empty. Interestingly, H.medicinalis does not produce any gut enzymes. Symbiotic bacteria, principally Aeromonas hydrophila, which are living in the leech’s gut, carry out the digestion. The medical treatment with leeches is a sort of improvement of the much older tradition of bloodletting, which origins are suspected to go back as far as the Stone Age. The advantage of leeches is that it is less painful and easier to use for body parts which are hard/dangerous to access with blades like eyes and rectum. This usage of leeches in medicine in mind, it seems logical that, in the past, the word “leech” had a second meaning as medical practitioner. However, as Robert N. Mory et al. (2000) pointed out, this is an example of folk etymology: a “type of linguistic development, in which an apparently logical connection is used to explain (or is understood as) the development of one meaning from another”. In reality, "leech" and "leech", the worm and the physician, have two different origins. Both are based on the Old English word “leace”. However, while the worm “leech” came from the Middle Dutch lieke, the physician “leech” has its origin in Germanic languages including Old Frisian letza, Old Saxon laki, and Old High German lakki. So, even if leeches and leeches worked together in the past, the origins of their names are not connected. Today the word “leech” for physician is outdated. Today, “leech” is used to describe people which download from file-sharing sites without uploading anything. There the logical connection to the worm “leech” is obvious. Both are parasites: taking without giving something back. "The leech and the physician: biology, etymology, and medical practice with Hirudinea medicinalis."
Robert N. Mory, David Mindell, and David A. Bloom World journal of surgery 24.7 (2000): 878-883. Everybody knows this feeling: you are looking for a specific word. It is floating in your mind but you can not grab it. You know what it means, are able to recall synonyms. Sometimes you also have a clue how it sounds like… the initial letter, the syllable length. Although you are not able to immediately find the right word you are looking for you know immediately if a word somebody else suggests is the one you are looking for or if it’s not. This mental state in which you can’t recall a familiar word but words of similar form and meaning is called "tip of the tongue" (TOT) phenomenon. In 1966 Roger Brown and David McNeill published a paper in which they tried to analyze the TOT phenomenon. They read the definition of uncommon English words to fifty-six Harvard and Radcliffe undergraduates and asked them to recall the word fitting to the definition before reading the target word. Sometimes this procedures created TOT states in single subjects were the person was aware of a word (right or wrong) fitting to the definition. In this case they asked the person to write down what he knows about the word: initial letter, number of syllables, words with similar meaning or words with similar sound. EXAMPLE The process of recalling parts and attributes of a word but not the complete word itself is called "generic recall". The study showed that indeed people in the TOT state can recall with significant success the number of syllables and the initial letter in a target word. Words with similar sound were most likely representing the right letters in the right position in the beginning and the end of the word, supporting the known order of attention in word reading: As long as the first and the last letter are in the right position people are most likely able to read the word even if the other letters in the middle of the word are unsorted. Looking at the “sound like” words which the persons listed up in the TOT state showed that there was a correlation between the similarity of the “sound like” words to the target words and the chance to find the target word on its own. Roger Brown and David McNeill explain this fact by describing the word memory as a keysort cards system. Each word we know is described by cards describing various features of the word. The cards are punched for various features of the words they describe. Therefore, even if the card with the target word is missing some letters or is unreadable, we are able to recall some facts about the word which then can help us to fill the gaps in the target card until we find the word. The “tip of the tongue” phenomenon
Roger Brown and David McNeill Journal of verbal learning and verbal behavior 5.4 (1966): 325-337 |
IdeaI love to increase my general science knowledge by reading papers from different fields of science. Here I share some of them. Archiv
März 2018
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