SCIENCE 



NEW YORK, MAY 6, 1892. 



PEELIMINAEY NOTE ON THE RELATIONS OF THE 

 MOTOR MUSCLES OF THE EYES TO CERTAIN 

 FACIAL EXPRESSIONS. 



In the course of some years of close obs>ervation of the 

 anomalies of the muscles which govern the movements of 

 the eyes, the fact that remarkable changes often follow the 

 modification of the conditions of these muscles led me not 

 Only to regard with greater care these facial changes, but to 

 bring to the subject the aid of photography, by which means 

 only these expressions could be accurately registered. Pho- 

 tographic portraits giving a direct front-view of more than 

 two thousand persons have thus been made. In each case 

 a record, as full and as accurate as I have been able to ob- 

 tain, of the state of these eye muscles has been made, and in 

 the majority of the cases careful observations have been re- 

 peated many times during some weeks or months. 



We have thus, for the first time, a series of observations 

 in which the facial expressions are registered by photography, 

 while painstaking determinations of the ocular-muscle condi- 

 tions are faithfully recorded. 



Beyond this, in a great number of instances, photographs 

 have been taken at various stages of modification of these 

 muscles, thus affording a comparative study of the face under 

 varying conditions of the eye muscles. 



The result of this study has been to demonstrate that cer- 

 tain well-defined types of facial expression are not only asso- 

 ciated with but are dependent upon certain relative tensions 

 of the oculo motor muscles. 



An elementary knowledge of the conditions of these mus- 

 cles, as commonly presenting themselves in practice, is neces- 

 sary to an understanding of what follows. 



In an ideal condition of the eye muscles, they should, 

 when the minimum of effort of all the opposing forces is 

 exercised, so adjust the eyes that the lines of vision will be 

 practically parallel. More exactly, the adjustments should 

 be such that the visual lines would meet only at a point 

 situated at a very considerable distance in front of the eyes. 



This condition of perfect equilibrium of all the opposing 

 eye-muscles does not always exist. Indeed, such a condition 

 is the exception. (In this statement no reference to the condi- 

 tions known as strabismus or squint is intended; in fact, 

 in this connection all such exaggerated anomalies are left 

 absolutely out of consideration, the purpose being to con- 

 sider only the conditions in which single vision with the 

 two eyes is maintained). 



The condition of equilibrium above described is known as 

 orthophoria. 



In case of a normal excess of tension on the part of the 

 muscles which rotate the eyes inward, the visual lines, should 

 no restraining force be brought into action, would drift to- 

 ward each other and visual confusion would result. In that 

 case, by means of a voluntary but unconscious effort on the 

 part of the opposing muscles, the lines of vision might be 

 properly adjusted. This condition, in which there is a nor- 

 mal tendency of the visual lines to approach, but in which 



there is ability to restrain that tendency, is known as eso- 

 phoria. 



The opposite condition, in which the normal tension of 

 the muscles which rotate the eyes outward predominates and 

 which, if unrestrained, would cause the visual lines to di- 

 verge, is known as exophoria, 



Another condition, in which a tendency of one of the 

 visual lines to rise above its fellow is found, is known as 

 hyperphoria. 



Compound conditions called hyperesophoria and hyper- 

 exophoria are also found. The terms suggest the elements 

 of these conditions. 



In the great majority of persons, some one of these so- 

 called anomalies is to be found. While the condition of 

 absolute orthophoria is, perhaps, not to be expected, that of 

 a near approach to it is sometimes, although exceptionally, 

 found. 



The conditions of esophoria and of exophoria are much 

 more common. Hyperphoria would appear to be somewhat 

 less common than the last two. 



With each of these conditions of relative tensions of the 

 eye muscles is commonly associated a type of expression 



sometimes slightly but often extremely well marked. That 

 there are found apparent exceptions to this rule, as to most 

 other rules, is true. Yet the law is so generally prevalent 

 as to enable us to classify nearly all faces by its assistance. 



The great elasticity of muscles, together with the peculiar 

 characteristics of the sub-dermal tissues in childhood and 

 early youth, and the loose and wrinkled character of the 

 skin in advanced age, to a greater or less degree disguise the 

 characteristic expressions arising from these various muscu- 

 lar tensions. The types are therefore most conspicuous in 

 early adult and in middle age. 



In the accompanying diagrams, I have endeavored to illus- 

 trate the peculiarities of four principal types of facial expres- 

 sion as governed by the eye muscles. 



With the state of equilibrium of these muscles, ortho- 

 phoria (Fig. 1), the expression is one of greater repose than 

 with any of the other states of the eye muscles. The eye- 

 brows, which constitute one of the most striking of all the 

 facial features, form each a moderate and regular curve, 

 marking the border of the orbit, the lower border of the brow 

 corresponding to the orbital border. The inner extremity 

 descends towards the nose, but does not turn downward into 

 the depression bounded by the nose and the orbit. There is 



