Perceptual and Motor Skills, 1978,47, 727-734. @) Perceptual and Motor Skills 1978
ASYMMETRY IN PERCEPTION OF THE SIDES OF THE HUMAN FACE GREGORY R. KARCH AND CLAUDE W. GRANT University o f Utah Summary.-The objective of this research was to determine if systematic differences occur in the way people ascribe meaning to right and left sides of the human face. Twenty-two faces, bilaterally symmetrical, were constructed from 11 phbtographs. These left- and right-constructed faces were rated 1 wk apart by 26 raters o n nine bipolar adjective scales selected for the evaluative, potency, and activity dimensions of the semantic differential (Osgood, 1961). Multivariate F tests indicated that on seven of the nine bipolar scales the leftand right-sided faces received significantly different ratings. Left facial constructions were rated as healthier, stronger, harder, more active, more excitable, and in the direction of bad on the good-bad scale. Right facial constructions were rated more sickly, weaker, more feminine, softer, more passive, calmer, and in die good direction on the good-bad scale.
There are many examples of bilateral asymmetry in nature (Gardner, 1964). Asymmetry has been documented in man in smdies of hand, eye, leg, and. ear dominance (Broadbent, 1954; Hildreth, 1949). Asymmetry is a curious fact in the functioning of the hemispheres of the human brain (Milner, 1961; Sperry, 1964). Asymmetry in the human face has been studied by Wolff (1933), McCurdy (1947), Lindzey (1752), and Gilbert and Bakan (1973). These researchers investigated the notion from folklore that one side of the face usually looks more like the person than the other side. In Wolff's (1933) studies it was determined that the right side of the face looked more like the full face of the person. From this observation he inferred that the right side of the face contained the more individual conscious, expressive or "public" character, while the left side was more private and unconscious. McCurdy (1949) and Lindzey (1952) replicated Wolff's findings and also found that the subjects said the right side more closely resembled the person than the left side. Gilbert and Bakan (1973) questioned that the resemblance was a function of the characteristics of the face itself. They thought it might be due to a perceptual bias in the observer. By photographically reversing the face with which the left and right bilateral constructions were compared they determined that the observed effect derives from asymmetrical left-field perceptual bias rather than the qualities in the faces themselves. They hypothesized that the perceptual bias might be due to a "right-hemisphered specialization for facial recognition, coupled with more direct image transfer from the left visual field to the right hemisphere." The "right-hemisphered specialization for facial
728
G. R. KARCH
&
C. W. GRANT
recognition" has been supported by work with patients who have suffered injuries to their right hemispheres (Milner, 1968; Yin, 1970). Oltman, Ehrlichman, and Cox ( 1977) further refined the parameters involved in perceptual biases related to the left and right sides of the human face. Rating subjects o n t h e e indices of field dependence they determined that those subjects in the most field-dependent quartile showed no significant degree of bias one way or the other towards the left or right visual fields; however, those in the most field-independent quartile showed a significant left-visual-field bias. A separate line of investigation on the perception of the face has been in the area of measurement of emotion and personality attributes of the face. Osgood (1966) reviewed the literature o n attempts to judge facial expression and concluded that expression can be more reliably judged by asking raters to use dimensional scaling rather than single word ascription. Hurwitz, Wiggins, and Jones (1975) have attempted to derive a semancic differential scale for facial attribution by having raters associate 2400 adjectives descriptive of personality to slides of 10 black and 1 0 white male faces. A set of 27 bipolar adjectives scales was selected as appropriate for the study of personality attribution to faces on the basis of ( a ) frequency of association, ( b ) judged relevance of adjective to faces, ( c ) judged commonness of opposite, and ( d ) judged commonness of adjective. The concern of this study was to investigate perceived systematic differences in the sides of the face, not as the sides compared with the natural face, but as they were rated in comparison with each other. Wolff's procedure (Wolff, 1933; Gilbert & Bakan, 1973) of splitting the face in half and splicing the left and right halves with their mirror images to form two separate, bilaterally symmetrical faces was followed. These faces were then rated on 9 bipolar semantic differential scales. The scales were chosen on the basis of their ability to assess dominant, aggressive, active, healthy, etc., traits. Four of the nine semantic differential scales were identical to those on the list developed by Hurwitz, Wiggins, and Jones (1975) in their "Face Differential." The semancic differential seems to be a natural instrument for making "polar" judgments related to the sides of the face. I n tradition and folklore throughout the world the left and right sides of the body have been "polarized." Many customs and observances have allocated different roles to the left and right sides based on beliefs about the respective sides (Hertz, 1960; Wile, 1934; Barsley, 1966; Lloyd, 1962; Needham, 1973). Usually the right side of the body is thought to be more proper, just., correct, equitable, fair, true, upright, righteous, advantageous, appropriate, and desirable than the left side. How such value-laden ascriptions came to be associated with the right and left sides of the body is difficult to say. But given the polar nature of language upon which the allocation of meaning in the semantic differential
ASYMMETRY IN PERCEPTION
729
is based (Osgood, 1961), given the tendency o i societies to polarize opposites such as left and right (Hertz, 1960; Lloyd, 1962), given the potency of the face as an object which conveys meaning (Osgood, 1966; Hurwitz, Wiggins, & Jones, 1975 ) , given that faces are less bilaterally symmetrical than they first appear (Gilbert, 1973), it makes sense to test whether systematic perceived differences between the left and right are present in the human face. Investigation of innate differences in facial laterality has additional significance in light of the Oltman, Ehrlichman, and Cox (1977) study. If there are biases toward the left visual field in the field-independent subjects, it would be important to determine if the side most often perceived has different affective information than the other side.
METHOD Photographs were taken of 37 male naval science cadets. Each was bilaterally symmetrical to the left side or the right side (Wolff, 1933; McCurdy, 1949; Lindzey, et al., 1952; Gilbert & Bakan, 1973). Each cadet was asked to sit in a chair and look straight ahead at the camera with a neutral facial expression. Care was taken to make sure that the subjects looked straight ahead because any lateral deviation produced distortions in the symmetricality of the facial constructions. The 11 photographs that were most symmetrical in construction were selected as stimuli. The left and right bilateral constructions of each face were made into slide form. All subjects whose photographs were used as stimuli reported that they were right-handed. The instrument used to rate the faces consisted of 9 bipolar adjective scales (see Table I ) , taken from the semantic differential (Osgood, 1361). Three bipolar adjective scales with high factor loadings were chosen from each of the evaluative, potency, and activity dimensions of the semantic differential. Procedure Left and right slide-constructions of the 11 faces were shown to 26 raters in 2 separate viewings held 1 wk. apart. The first week either the bilaterally symmetrical left or right facial constructions were shown. The order was randomly determined. The next week the other slide was shown. Each left and each right construction was rated on the nine adjective scales of the semantic differential. The order of the scales was randomly determined as was the direction of the poles. The 26 raters were mostly graduate students from two courses in psychology during the summer session. They ranged in age from 22 to 54 yr., with a mean age of 31.35 yr. Thirteen were male and 13 were female. There was no attempt to make any inferences about differences within the group of raters.
Analysis Ratings of the left versus the right bilateral constructions were analyzed by way of a multivariate F test, using a computer program produced by Clyde
730
G.R. KARCH
&
C. W. GRANT
Computing C0mpany.l This program also produced a set of correlations for each adjective. The correlational data are presented for general interest. Because the 9 bipolar adjectives were chosen from three factorial dimensions-activity, potency, and evaluative-it would be expected that each of the three adjectives chosen from within a dimension would be highly correlated. Such items would also be expected to yield similar results on the univariate F tests. Principal components coefficients are indices of the degree to which each univariate effect contributes to the over-all multivariate effect. High principal component coefficients are those which contribute most to the effect. The multivariate F tested differences between left and right facial constructions on the 9 bipolar adjectives of the semantic differential.
RESULTSAND DISCUSSION As shown in Table. 1 all of the potency bipolar adjectives (hard-soft, masculine-feminine, and strong-weak) are significantly correlated (p < .01) with one another; among the three evaluative bipolar adjectives good-bad and sociable-unsociable are significantly correlated (p .01); among the three activity bipolar adjectives, changeable-stable, and active-passive are significantly correlated ( p < .01). There are other significant correlations among the 9 scales. Those with the greatest number of intercorrelations are: strong-weak ( 5 ) , healthy-sickly (4), hard-soft ( 4 ) , masculine-feminine (3), and excitablecalm ( 3 ) . The more positive poles of these scales are descriptive of vibrance, dominance, and aliveness.
ASYMMETRY IN PERCEPTION OF THE SIDES OF THE HUMAN FACE GREGORY R. KARCH AND CLAUDE W. GRANT University o f Utah Summary.-The objective of this research was to determine if systematic differences occur in the way people ascribe meaning to right and left sides of the human face. Twenty-two faces, bilaterally symmetrical, were constructed from 11 phbtographs. These left- and right-constructed faces were rated 1 wk apart by 26 raters o n nine bipolar adjective scales selected for the evaluative, potency, and activity dimensions of the semantic differential (Osgood, 1961). Multivariate F tests indicated that on seven of the nine bipolar scales the leftand right-sided faces received significantly different ratings. Left facial constructions were rated as healthier, stronger, harder, more active, more excitable, and in the direction of bad on the good-bad scale. Right facial constructions were rated more sickly, weaker, more feminine, softer, more passive, calmer, and in die good direction on the good-bad scale.
There are many examples of bilateral asymmetry in nature (Gardner, 1964). Asymmetry has been documented in man in smdies of hand, eye, leg, and. ear dominance (Broadbent, 1954; Hildreth, 1949). Asymmetry is a curious fact in the functioning of the hemispheres of the human brain (Milner, 1961; Sperry, 1964). Asymmetry in the human face has been studied by Wolff (1933), McCurdy (1947), Lindzey (1752), and Gilbert and Bakan (1973). These researchers investigated the notion from folklore that one side of the face usually looks more like the person than the other side. In Wolff's (1933) studies it was determined that the right side of the face looked more like the full face of the person. From this observation he inferred that the right side of the face contained the more individual conscious, expressive or "public" character, while the left side was more private and unconscious. McCurdy (1949) and Lindzey (1952) replicated Wolff's findings and also found that the subjects said the right side more closely resembled the person than the left side. Gilbert and Bakan (1973) questioned that the resemblance was a function of the characteristics of the face itself. They thought it might be due to a perceptual bias in the observer. By photographically reversing the face with which the left and right bilateral constructions were compared they determined that the observed effect derives from asymmetrical left-field perceptual bias rather than the qualities in the faces themselves. They hypothesized that the perceptual bias might be due to a "right-hemisphered specialization for facial recognition, coupled with more direct image transfer from the left visual field to the right hemisphere." The "right-hemisphered specialization for facial
728
G. R. KARCH
&
C. W. GRANT
recognition" has been supported by work with patients who have suffered injuries to their right hemispheres (Milner, 1968; Yin, 1970). Oltman, Ehrlichman, and Cox ( 1977) further refined the parameters involved in perceptual biases related to the left and right sides of the human face. Rating subjects o n t h e e indices of field dependence they determined that those subjects in the most field-dependent quartile showed no significant degree of bias one way or the other towards the left or right visual fields; however, those in the most field-independent quartile showed a significant left-visual-field bias. A separate line of investigation on the perception of the face has been in the area of measurement of emotion and personality attributes of the face. Osgood (1966) reviewed the literature o n attempts to judge facial expression and concluded that expression can be more reliably judged by asking raters to use dimensional scaling rather than single word ascription. Hurwitz, Wiggins, and Jones (1975) have attempted to derive a semancic differential scale for facial attribution by having raters associate 2400 adjectives descriptive of personality to slides of 10 black and 1 0 white male faces. A set of 27 bipolar adjectives scales was selected as appropriate for the study of personality attribution to faces on the basis of ( a ) frequency of association, ( b ) judged relevance of adjective to faces, ( c ) judged commonness of opposite, and ( d ) judged commonness of adjective. The concern of this study was to investigate perceived systematic differences in the sides of the face, not as the sides compared with the natural face, but as they were rated in comparison with each other. Wolff's procedure (Wolff, 1933; Gilbert & Bakan, 1973) of splitting the face in half and splicing the left and right halves with their mirror images to form two separate, bilaterally symmetrical faces was followed. These faces were then rated on 9 bipolar semantic differential scales. The scales were chosen on the basis of their ability to assess dominant, aggressive, active, healthy, etc., traits. Four of the nine semantic differential scales were identical to those on the list developed by Hurwitz, Wiggins, and Jones (1975) in their "Face Differential." The semancic differential seems to be a natural instrument for making "polar" judgments related to the sides of the face. I n tradition and folklore throughout the world the left and right sides of the body have been "polarized." Many customs and observances have allocated different roles to the left and right sides based on beliefs about the respective sides (Hertz, 1960; Wile, 1934; Barsley, 1966; Lloyd, 1962; Needham, 1973). Usually the right side of the body is thought to be more proper, just., correct, equitable, fair, true, upright, righteous, advantageous, appropriate, and desirable than the left side. How such value-laden ascriptions came to be associated with the right and left sides of the body is difficult to say. But given the polar nature of language upon which the allocation of meaning in the semantic differential
ASYMMETRY IN PERCEPTION
729
is based (Osgood, 1961), given the tendency o i societies to polarize opposites such as left and right (Hertz, 1960; Lloyd, 1962), given the potency of the face as an object which conveys meaning (Osgood, 1966; Hurwitz, Wiggins, & Jones, 1975 ) , given that faces are less bilaterally symmetrical than they first appear (Gilbert, 1973), it makes sense to test whether systematic perceived differences between the left and right are present in the human face. Investigation of innate differences in facial laterality has additional significance in light of the Oltman, Ehrlichman, and Cox (1977) study. If there are biases toward the left visual field in the field-independent subjects, it would be important to determine if the side most often perceived has different affective information than the other side.
METHOD Photographs were taken of 37 male naval science cadets. Each was bilaterally symmetrical to the left side or the right side (Wolff, 1933; McCurdy, 1949; Lindzey, et al., 1952; Gilbert & Bakan, 1973). Each cadet was asked to sit in a chair and look straight ahead at the camera with a neutral facial expression. Care was taken to make sure that the subjects looked straight ahead because any lateral deviation produced distortions in the symmetricality of the facial constructions. The 11 photographs that were most symmetrical in construction were selected as stimuli. The left and right bilateral constructions of each face were made into slide form. All subjects whose photographs were used as stimuli reported that they were right-handed. The instrument used to rate the faces consisted of 9 bipolar adjective scales (see Table I ) , taken from the semantic differential (Osgood, 1361). Three bipolar adjective scales with high factor loadings were chosen from each of the evaluative, potency, and activity dimensions of the semantic differential. Procedure Left and right slide-constructions of the 11 faces were shown to 26 raters in 2 separate viewings held 1 wk. apart. The first week either the bilaterally symmetrical left or right facial constructions were shown. The order was randomly determined. The next week the other slide was shown. Each left and each right construction was rated on the nine adjective scales of the semantic differential. The order of the scales was randomly determined as was the direction of the poles. The 26 raters were mostly graduate students from two courses in psychology during the summer session. They ranged in age from 22 to 54 yr., with a mean age of 31.35 yr. Thirteen were male and 13 were female. There was no attempt to make any inferences about differences within the group of raters.
Analysis Ratings of the left versus the right bilateral constructions were analyzed by way of a multivariate F test, using a computer program produced by Clyde
730
G.R. KARCH
&
C. W. GRANT
Computing C0mpany.l This program also produced a set of correlations for each adjective. The correlational data are presented for general interest. Because the 9 bipolar adjectives were chosen from three factorial dimensions-activity, potency, and evaluative-it would be expected that each of the three adjectives chosen from within a dimension would be highly correlated. Such items would also be expected to yield similar results on the univariate F tests. Principal components coefficients are indices of the degree to which each univariate effect contributes to the over-all multivariate effect. High principal component coefficients are those which contribute most to the effect. The multivariate F tested differences between left and right facial constructions on the 9 bipolar adjectives of the semantic differential.
RESULTSAND DISCUSSION As shown in Table. 1 all of the potency bipolar adjectives (hard-soft, masculine-feminine, and strong-weak) are significantly correlated (p < .01) with one another; among the three evaluative bipolar adjectives good-bad and sociable-unsociable are significantly correlated (p .01); among the three activity bipolar adjectives, changeable-stable, and active-passive are significantly correlated ( p < .01). There are other significant correlations among the 9 scales. Those with the greatest number of intercorrelations are: strong-weak ( 5 ) , healthy-sickly (4), hard-soft ( 4 ) , masculine-feminine (3), and excitablecalm ( 3 ) . The more positive poles of these scales are descriptive of vibrance, dominance, and aliveness.
