There are several reasons people bite their nails. With careful observation, you can accurately determine which, and ultimately open the door to much more revealing personality information. The scientific term for the serious condition of chronic nail-biting is called onychophagia.
The three main reasons people bite their nails are self-soothing behavior, stimulation and compulsive hygienic perfectionism.
Self-soothers bite their nails in order to pacify anxiety, stress or general heightened nerves. Identifying self-soothing nail biters is relatively easy. The nails will have a general appearance of being bitten and will usually be accompanied by recently picked cuticles and will not be symmetrical and perfect. The appearance of the nails on the dominant hand will usually have more recent bite marks and the fingers more accessible to the mouth (index, thumb and middle fingers) will have been bitten more than the others. This is the key difference in distinguishing between habitual perfectionism nail-biting and self-soothers. The non-dominant hand will be less bitten, have less self-inflicted cuticle damage from picking. Some say self-soothing nail biting is directly related to thumb-sucking and others assert it's unrelated. For our purposes, however, it's absolutely irrelevant. This form of nail biting is, however, a form of stress-induced self mutilation. In people who do this behavior, those who also have mild to moderate self confidence issues and social fears will feel self-conscious about this behavior and it will often induce even more nail-biting as a tension-release. Because this habit is a repetitive disorder, if it is a condition that causes lifestyle impairment, it may be classified as an OCD-type behavior, which will run in families. Use this to read and make assumptions about parents and siblings as well.
Males are more likely than females to continue biting nails into adulthood, probably due to their being less concerned about manicures, perfection of appearance and nail polish.
Stimulation nail-biters will bite nails to pass the time. Reading the difference between self-soothing and stimulators is relatively easy if you have the chance to make an observation longer than a momentary glimpse. Stimulators will bite both hands more readily and will not likely have picked cuticles.
Hygienic-perfectionist biters will continuously bite nails in order to smooth rough edges, search for any asymmetry or 'defect' and will keep biting in order to 'correct' what they believe are unsightly imperfections in the nail edges and cuticles. Perfectionists will have smoother, but obviously bitten nails. Cuticles may be picked at, but will not usually have skin fragments protruding, as they will have bitten them off in an attempt to correct imperfections. When reading perfectionists, it is pretty common to also see hair-pulling and other hygienic gestures. These people are also more likely to pick lint from clothing, pick at 'imperfections' like pimples and whiteheads on the face. Perfectionists will leave evidence of their habits in the form of reddening of the cuticles, nails bitten too close to the quick and excessive makeup covering blemishes that have been 'corrected' on the face and neck.
There is a fourth reason that is somewhat unremarkable that you will see nail-biting. Simple laziness, or not having access to a nail trimmer. These people will be less concerned about evenness, symmetry and appearance. You will be able to easily see the nails are bitten and the non-dominant hand will be visibly less even and manicured.
As a note in this section, when you have the opportunity to witness a nail-biter in action, pay close attention to the associated behaviors. If they don't look at the nails after each bite, they are likely soothing or stimulating. If they are looking after each bite, especially when you see them turn their hand at different angles so they can be sure to see their nails from a similar angle others will, you know they are in the perfectionist bracket.
Now, what do they do with the nails themselves after they have been bitten? Some will save them in a pile to toss into the trash later, some will simply spit them out regardless of where they are and some will put them in their pockets or purse. The revealed personality traits with each of these nail-disposal behaviors is dramatically different in terms of extroversion, agreeableness and compassion. The ones who save a pile to toss later will be more conscientious and agreeable. The 'spitters' will usually be more extroverted and have much less compassion, while the ones who stash nails in pockets will show to be very reserved and introverted, scoring high on the compassion scale.
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