Hello. If the child sucks his finger when he is nervous, then, first of all, it is necessary to eliminate the reason for which he is anxious. The fact is that the sucking reflex, given to children from birth, provides them with emotional calm and stability. Sucking is often associated with a sense of security; this is precisely the period when a child sucks mother’s breast.
With age, children learn to calm themselves differently. With your child, either this did not happen, or after some kind of stress, it renewed again. You need to carefully watch your daughter and track the moments that lead to finger sucking. Understand that it is in these situations that may disturb the child. Also try to talk to her about her experiences right away in these situations. "Are you troubled right now? What exactly is bothering you and how can I help?" Children suck their fingers to feel the psychological comfort.
If your child could not get rid of such addiction before they reach the age of 5, it is still fraught with the formation of the wrong bite. Among preschool children and children of primary school age, the owners of this habit are no longer so many. But those children who have not had time to get rid of it may experience problems in communicating with their peers. The reasons for which he sucks his finger at this age are no longer associated with the physiological processes in his body. They should be sought, rather, emotional and psychological overtones. Sometimes this is one of the symptoms of the disease of the central nervous system, so consultation and treatment of a neurologist is necessary.
The child either feels uncomfortable or lacks your parental attention. Maybe he has difficulty communicating with peers at school. Then thumb sucking becomes his personal sedative. Of course, you can put anything on his hands, and he will “forget” how to suck a finger. But his problems will result in the fact that he will bite, for example, nails to the blood. Or twist the hair and pull the strands.
There are many ways to get rid of this habit. The most popular one is to smear a finger with mustard or something else so unpleasant to the child - for example, there is a special varnish, “Nekusayka”. Also with younger children usually use fairy tale therapy and sand therapy.
You can go to a psychologist at classes and try to eliminate the cause and get rid of this habit forever, if it is not neurology. All the best!