if you let mind play over some of the  tactiturn people you know , you will realize that their abnormal disinclination to conversation makes them seem morose ,sullen and unfriendly.cal Coolidge,s was world  famous and no oneiam sure ever conceived bof him as cheerful overfriendly ,or particularly sociable

There are doughtless many possible causes

of such verbal rejection of the word ..parhaps lack of self assurance ,feeling inadequacy or hostity ,exceeessive seriousness or introspection or just plain heaving nothing to say .maybe in coolidge,s case ,he was saving of the words

after he did not chose to run,,  in 1928,he wrotea daily colummfor the New york heraid tribune ata rumored price of two dollars a word , and accordingto most critics ,he had seemed wiser when he kept silent

coolidge hailed from new England and taciturnity ,in that part of the country ,so some people say ,is considered  a virtue . who knows the cause may be geographical  and climatic ,rather then phycological ,