Perceptual and Motor Skills, 1975,40, 887-893. @ Perceptual and Motor Skills 1975
MCnTIDIMENSIONAL SCALING OF PICTORIAL INFORMATIVENESS1 JAMES R. ANTES A N D LEROY A. STONE University of North Dakota Summary.-The dimensions used in the judgment of the informativeness of piccure sections were investigated by means of a recently proposed methodology, multidimensional similarity analysis. 10 judges (college students) rated the informational similarity of 32 areas within a single picture. The five extracted dimensions accounted for 8 6 % of the judgmental variance and were all readily interpretable. These dimensions were discussed with respect to an earlier study in which eye movements of subjects viewing this picture were recorded.
A major advance in the study of picture perception was made by Mackworth and Morandi (1967) who devised a method of scaling the information value, or "informativeness," of different regions within a single picture. Their method involved cutting a picture into equal sized pieces and presenting them individually to a group of Ss who raced them in terms of informativeness. When different Ss viewed the intact pictures, they tended to concentrate their eye fixations on regions which had been rated as highly informative. Areas rated uninformative received few or no fixations. Subjective ratings were clearly related to visual exploration of the scenes. Because of the inherent complexity of pictures, this method represents an advance over the lines and angles approach of Attneave and Arnoult (1956) and has stimulated renewed interest in the perception of pictures. For example, Pollack and Spence ( 1968) showed search times to be shortest and errors lowest when the searched-for pictorial segments were rated highly informative. Antes (1974) described the time course of Ss' visual exploration of complex scenes employing a subjective rating method. However, another issue should be considered regarding this method of informativeness rating. It is not known what factors comprise Ss' judgments of informativeness. It is certainly conceivable that matters of physical complexity, brightness, meaning, and spatial relationships may all be considered in Ss' ratings. However, S is required to respond using only one dimension. It would thus be desirable to determine what variables constitute the judgment of informativeness, certainly a multidimensional attribuce. Visual exploratory behavior could then be more clearly related to specific aspects of the piccures. Stone and Coles (1970, 1971a; Coles & Stone, 1972; Stone, Coles, & Lindem, 1970) have recently revised a similarity analysis model of multidimensional 'This research was supported in part by a grant from the University Committee on Research, University of North Dakota. Reprint requests should be addressed to James R. Antes, Deparunent of Psychology, University of Notch Dakota, Grand Forks, North Dakota 58201.
888
J. R. ANTES & L. A. STONE
scaling first proposed by Ekman (1954). The method locates percepts on 92 exrracted common hypothetical judgmental-dimensions. Given the assumption (Ekman, 1965 ) that multidimensional percepts are judged to be psychologically similar because they possess, to varying degrees, some of the same basic psychological content, the constructed dimensions may then be viewed as rhe dimensions common to the percepts judged. In the present experiment, ratings of regions within a single picture were subjected to the Stone-Coles similarity analysis. It was expected that the dimensions extracted by this kind of judgmental analysis would represent those variables considered by judges in their rating of pictorial informativeness. Then it was hoped that these judgmental dimensions could be related to visual exploratory behavior.
METHOD Judges (1s) were 10 volunteers ( 3 females) from the introductory psychology course at the University of North Dakota. The stimuli were 32 picture segments from "Morning on the Cape" by Leon Kroll, shown in Fig. 1. This picture has been used in a previous eyemovement experiment (Antes, 1974) and eye fixation records and informativeness ratings for male and female college students are available for each picture segment. Criteria for determining size and shape of the segments are detailed in Antes ( 1974). In general, segment boundaries were decided on the basis of size, uniformity of eye fixation density within a segment, and unity of meaning of each segment. The Stone-Coles similarity analysis (Stone & Coles, 1970) requires that Js estimate the degree of over-all similarity of all pair comparisons of the stimulus set investigated. Since there were 32 pictures seccions to be evaluated, the number of pair comparisons was 496. Each J was given a randomized deck of 496 computer cards, on each card of which were printed the numbers which named the picture sections to be compared. Projected onto a screen in front of 1s was the intact picture and a reproduction.of the picture divided into the 32 numbered sections, as it appears in Fig. 1. The 1s were instructed to rate the degree of over-all similarity in amount of information conveyed for each pair of picture seccions as it immediately came to mind using a percent similarity scale on which 0 indicated complete dissimilarity and 100 indicated identity. Judges wrote their similarity estimates directly on the computer cards, which were punched on a later occasion and submitted for the data analysis. The judgment task was quite long and required three separate sessions of 45 min. duration each to complete. RESULTSAND DISCUSSION To determine the degree of agreement among judges a 10 X 10 interjudge
SCALING OF PICTORIAL INFORMATIVENESS
FIG. 1. "Morning on the Cape" by Leon Kroll as it appeared to Is, both Intact (above) and divided into numbered sections (below). (Reproduced with permission, Museum of Art, Carnegie Institute, Pittsburgh)
Pearsonian correlation matrix was computed on the basis of the 496 estimates made by each I. This matrix was then factor analyzed and three factors were extracted. The first factor accounted for 41% of the interjudge variance and seven of the judges loaded highly on it (loadings of .5 or higher). The second factor accounted for 11% and had high loadings from two of the remaining judges. The final factor accounted for 10% of the variance and the remaining judge loaded greater than .5 on it. Since it appeared that the 10 Is did not exhibit a single judgmental approach, only the seven Js.with high loadings on the first factor were included in the subsequent analysis. The 496 judgments of each J were averaged across the
j. R. ANTES &
890
L. A. STONE
seven Is and cast into a 32 X 32 full symmetric matrix of mean estimates of similarity. Consistent with the method of Stone and Coles (1970), the columns of this mean similarity matrix were intercorrelated to produce a new 32 X 32 matrix of correlational similarities. The matrix was then factor analyzed with the limiting eigenvalue set at 1.0. Five orthogonal judgment factors were extracted and rotated to a varimax criterion. These five rotated factors, shown with factor loadings in Table 1, accounted for 86% of the common variance of the mean estimations of similarity. The factor loadings on each factor were examined to determine if the psyTABLE 1 ROTATEDJUDGMENTAL DIMENSIONS ~~ATRIX Picture Section
1 2 3 4 5 G 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 %
u'
accounted for
I
I1
.90 .92 .95 .91 .92 .93 .92 .49 .20 -.58 -.GO -.03 -.44 .38 -.59 -.I5 .07 -.53 -.30 -.61 -.GO -.27 -.61 -.35 -.I2 -.I3 -.63 -.04 -.66 -.I5 720 -.30 39.9
.15 .13 .08 .lo .13 .09 .15 -.35 .65 .06 .ll .33 .24 .31 .12 .20 -.09 -.59 -.49 -.I4 -.05 .04 -.05 -.I4 -.07 -.08 -.64 .37 -.I5 .19 -.01 .02 23.4
Ill
-.I3 -.lo
-.09 -.I9 -.09 -.lo -.I2 -.09 .23 -.50 -.65 .12 -.I5 -.04 -.49 .12 .01 -.49 -.58 -.I7 -.32 -.08 -.24 .25 .43 .33 -.I7 .82 .01 .91 .91 .85 10.9
IV
V
.29 .27 .23 .29 .27 .26 .30 .41 .12
.04 .08 .OO .06 .02 .09 .02 .51 .31
.Ol
-.GO
.09 -33 -.70 .14 -.40 -.07
-.30 .72 .31 .73 -.07 .87 .91 -.I7 -.I8 -.57 -.GI -.08 -.30 -.I3 .40 .45 -,I6 -.I3 -.57 .06 .05 .18 4.8
.I0
.09 -.07 .15 .I9 -.83 -.54 -.81 -.69 -.68 .12 -.06 .23 -.04 -.I6 -.09 6.6
ha .94 .95 .98 .96 .94 .96 .98 .80 .63 .95 .89 .75 .86 .80 .78 .83 .84 .91 .71 .77 .87 .78 .8 1 .88 .84 .79 .87 .83 .84 .90 .90 .85 86
SCALING OF PICTORIAL INFORMATIVENESS
891
chological nature of each dimension could be readily labeled or reified. T o aid this identification process and to relate the extracted dimensions to behavior the factor loadings were correlated with density of eye-fixations, mean duration of eye fixation and individual ratings of informativeness for each segment of this picture, previously obtained from another sample of Ss (Antes, 1973). These correlations are displayed in Table 2.
TABLE 2 CORRELATIONS OF FACTOR LOADINGSWITH DATAFROMANTES (1973) Factor
Density of Eye-fixation
I 11 111
-.20 .23 -.44* -.24 .23
IV V
*p
< .05.
tp
Duration per Eye-fixation -. 16 -.35* -.47
.15 -.I4
t
Rating of Informativeness -.70t -.23 -.46t
-.39* -.I5
< .01.
Factor I, accounting for 39.9% of the variance following rotation, was apparently a bipolar dimension which was tentatively labeled presence vs absence of information. Receiving positive loadings were segments containing sky or objects in the background with few identifiable features. Sections containing elements which were more readily identifiable and more clearly conveying information received negative loadings. As might be expected, the factor loadings on this dimension correlated highly with informativeness ratings of the picture segments (Table 2 ) . Also, the segments having negative factor loadings tended to receive the greater density of eye fixations and greater average duration per eye fixation, however these relationships did not reach statistical significance. Factor I1 accounted for 23.4% of the judgmental variance following totation. Loadings on this dimension were seemingly related to location of the segments and was labeled as left vs right. Receiving the highest positive loading was section 9, on the left border of the picture, while sections 18, 19, and 27, which form the right border, received the highest negative loadings. The point-biserial correlation between factor loadings and section location (left vs right) was .50 ( p < .01). Table 2 shows that, when correlated with the data from Antes (1973), loadings on this dimension were unrelated to density of eye-fixations or ratings of informativeness, however displayed a slight relationship with duration of fixation. Mean duration for *eye-fixations tended to be higher for sections with negative loadings, in general, those on the right side of the picture. Factor-dimension I11 accounted for 10.9% of the mean similarity variance following rotation and was labeled meaningfulness. Of those segments with
892
J. R. ANTES
&
L. A. STONE
readily identifiable features (and receiving negative loadings on Factor I ) , those segments clearly conveying meaning regarding understanding of the picture (Sections 10, 11, 15, 18, and 19) received the highest negative loadings. Receiving high positive loadings were those segments with identifiable features which were apparently unrelated to understanding the meaning of the picture (Sections 28, 30, 31, and 32). "Meaningful" segments (negative loadings) received a higher density of fixation, greater duration per fixation and higher ratings of informativeness than segments with positive loadings (Table 2 ) . Dimension IV, accounting for 6.6% of the judgmental variance following rotation, was apparently another location dimension and was tentatively labeled inner vs outer. High negative loadings were received by those segments in the center part of the picture (Sections 13, 22, 23, 24, 25, and 26). The pointbiserial correlation between factor loadings and location (border segment vs non-border segment) was .52 ( p < .01). Although unrelated to density or duration of eye-fixations, this factor bore a slight relationship to ratings of informativeness. Center sections (negative loadings) were rated more highly informative than sections with positive factor loadings. Factor V accounted for 4.8% of the mean similarity variance. This dimension also was apparently related to pictorial location and was labeled foreground us background. Sections whose elements were clearly in the foreground of the picture (numbers 10, 20, 21 and 29) received high negative loadings. Sections which formed the horizon of the picture (12, 14, 16 and 17) received high positive loadings. Factor loadings did not significantly correlate with density of eye-fixations, duration of eye-fixations, or ratings of informativeness of Antes (1973). These five factors seemed to be readily interpretable and collectively they accounted for 86% of the mean common variance of the similarity estimations. Factors I and 111 were apparently related to content of the picture and the other three factors were related to physical location within the picture. In this regard it is interesting to note that Schissler (1969) reported no difference in ratings of picture-informativeness if the intact picture was viewed or not viewed prior to rating individual pieces. In the present experiment, had the Js not viewed the intact picture and had rated pairs of sections individually then only minimal location information would have been available and presumably Factors 11, IV and V would not have emerged. As Table 2 suggests, however, the clearest relationship to informativeness ratings is with the "picture content" factors ( I and III), implying that, while similarity judgments may be based on content and location, ratings of informativeness are based primarily on the presence of identifiable features and the meaningfulness of these elements. By far the strongest relationship to visual exploratory behavior (density and duration of eye-fixations) was with Factor 111 labeled meaningfulness. Sig-
SCALING OF PICTORIAL INFORMATIVENESS
893
nificant correlations should have been expected with Factor I; however, such were not obtained. This might be due to the negative loadings of Factor I (information present) not showing sufficient variability necessary to be sensitive to variation in eye-fixations. This experiment has demonstrated the potential fruitfulness of multidimensional scaling methods in examining dimensions used in the judgment of pictorial informativeness. I t should be noted that, although the Stone-Coles method was the multidimensional scaling procedure employed, this particular method has a history of producing judgmental analyses very similar to those produced by other well known "distance" methods (cf. Stone, 1971b; Stone & Coles, 1971). Five readily identifiable factors were extracted which were related to other independently determined measures of informativeness and visual exploration. It remains a task for future research to determine the relationship of the presently extracted kinds of dimensions to other methods of rating informativeness (see Schissler, 1969) and other picture stimuli. REFERENCES ANTES, J. R. Eye fixations as a function of informativeness. Unpublished doctoral dissertation. Iowa State Univer.. 1973. ANTES,J. R. The time course of picture viewing. Journal o f Experimental Psychology, 1974, 103, 62-70. A'ITNEAVE,F., & ARNOULT, M. D. The quantitative study of shape and pattern discrimination. Psychological Bulletin, 1956, 53, 452-47 1. COLES,G . J.. & STONE,L. A. A new methodological revision of Ekman's "content" model of multidimensional similarity analysis. Multivariate Behavioral Resemch, 1972, 7, 85-107. EKMAN,G. Dimensions of color vision. Jorirnul o f Psychology, 1954, 38, 467-474. EKMAN. G. TWOmethods for the analysis of percepmal dimensionality. Psrceptual and Motor Skills, 1965, 20, 557-572. MACKWORTH, N. H., & MORANDI, A. J. The gaze selects informative derails within pictures. Perception d Psychophysics, 1967, 2, 547-551. POLLACK, I., & SPENCE, D. Subjective pictorial information and visual search. Perception & Psychophysicr, 1968, 3, 41-44. SCHISSLER, D. R. Analysis of piccures by subjective ratings and by eye fixations. journal o f General Psychology, 1969, 81, 83-94. STONE,L. A. Congruent multidimensional scaling results obtained using the halo-model and the Stone-Coles method-model. Perceptual and Motor Skills, 1971. 33, 525526. STONE,L. A,. & COLES,G. J. Correlational similarity: the basis for a new revised method of similarity analysis. Studia Psychologica (Bsatislava), 1970, 12, 258264. STONE, L. A., & COLES,G. J. Dimensions of color revisited. Journal o f Psychology, 1971, 77, 79-87. ( a ) STONE,L. A., & COLES,G. J. Psychology graduate students' multidimensional perceptions of their psychology faculty. Acta Psychologica, 1971, 35, 364-377. ( b ) STONE,L. A., COLES,G. J., & LINDEM,A. C. Multidimensional evaluation structure analysis ( M E S A ) : a complete scaling system usable for a multiplicity of purposes. Grand Forks, N . D.: Judgmetrics, 1970.
Accepted Mmch 25, 1975.
MCnTIDIMENSIONAL SCALING OF PICTORIAL INFORMATIVENESS1 JAMES R. ANTES A N D LEROY A. STONE University of North Dakota Summary.-The dimensions used in the judgment of the informativeness of piccure sections were investigated by means of a recently proposed methodology, multidimensional similarity analysis. 10 judges (college students) rated the informational similarity of 32 areas within a single picture. The five extracted dimensions accounted for 8 6 % of the judgmental variance and were all readily interpretable. These dimensions were discussed with respect to an earlier study in which eye movements of subjects viewing this picture were recorded.
A major advance in the study of picture perception was made by Mackworth and Morandi (1967) who devised a method of scaling the information value, or "informativeness," of different regions within a single picture. Their method involved cutting a picture into equal sized pieces and presenting them individually to a group of Ss who raced them in terms of informativeness. When different Ss viewed the intact pictures, they tended to concentrate their eye fixations on regions which had been rated as highly informative. Areas rated uninformative received few or no fixations. Subjective ratings were clearly related to visual exploration of the scenes. Because of the inherent complexity of pictures, this method represents an advance over the lines and angles approach of Attneave and Arnoult (1956) and has stimulated renewed interest in the perception of pictures. For example, Pollack and Spence ( 1968) showed search times to be shortest and errors lowest when the searched-for pictorial segments were rated highly informative. Antes (1974) described the time course of Ss' visual exploration of complex scenes employing a subjective rating method. However, another issue should be considered regarding this method of informativeness rating. It is not known what factors comprise Ss' judgments of informativeness. It is certainly conceivable that matters of physical complexity, brightness, meaning, and spatial relationships may all be considered in Ss' ratings. However, S is required to respond using only one dimension. It would thus be desirable to determine what variables constitute the judgment of informativeness, certainly a multidimensional attribuce. Visual exploratory behavior could then be more clearly related to specific aspects of the piccures. Stone and Coles (1970, 1971a; Coles & Stone, 1972; Stone, Coles, & Lindem, 1970) have recently revised a similarity analysis model of multidimensional 'This research was supported in part by a grant from the University Committee on Research, University of North Dakota. Reprint requests should be addressed to James R. Antes, Deparunent of Psychology, University of Notch Dakota, Grand Forks, North Dakota 58201.
888
J. R. ANTES & L. A. STONE
scaling first proposed by Ekman (1954). The method locates percepts on 92 exrracted common hypothetical judgmental-dimensions. Given the assumption (Ekman, 1965 ) that multidimensional percepts are judged to be psychologically similar because they possess, to varying degrees, some of the same basic psychological content, the constructed dimensions may then be viewed as rhe dimensions common to the percepts judged. In the present experiment, ratings of regions within a single picture were subjected to the Stone-Coles similarity analysis. It was expected that the dimensions extracted by this kind of judgmental analysis would represent those variables considered by judges in their rating of pictorial informativeness. Then it was hoped that these judgmental dimensions could be related to visual exploratory behavior.
METHOD Judges (1s) were 10 volunteers ( 3 females) from the introductory psychology course at the University of North Dakota. The stimuli were 32 picture segments from "Morning on the Cape" by Leon Kroll, shown in Fig. 1. This picture has been used in a previous eyemovement experiment (Antes, 1974) and eye fixation records and informativeness ratings for male and female college students are available for each picture segment. Criteria for determining size and shape of the segments are detailed in Antes ( 1974). In general, segment boundaries were decided on the basis of size, uniformity of eye fixation density within a segment, and unity of meaning of each segment. The Stone-Coles similarity analysis (Stone & Coles, 1970) requires that Js estimate the degree of over-all similarity of all pair comparisons of the stimulus set investigated. Since there were 32 pictures seccions to be evaluated, the number of pair comparisons was 496. Each J was given a randomized deck of 496 computer cards, on each card of which were printed the numbers which named the picture sections to be compared. Projected onto a screen in front of 1s was the intact picture and a reproduction.of the picture divided into the 32 numbered sections, as it appears in Fig. 1. The 1s were instructed to rate the degree of over-all similarity in amount of information conveyed for each pair of picture seccions as it immediately came to mind using a percent similarity scale on which 0 indicated complete dissimilarity and 100 indicated identity. Judges wrote their similarity estimates directly on the computer cards, which were punched on a later occasion and submitted for the data analysis. The judgment task was quite long and required three separate sessions of 45 min. duration each to complete. RESULTSAND DISCUSSION To determine the degree of agreement among judges a 10 X 10 interjudge
SCALING OF PICTORIAL INFORMATIVENESS
FIG. 1. "Morning on the Cape" by Leon Kroll as it appeared to Is, both Intact (above) and divided into numbered sections (below). (Reproduced with permission, Museum of Art, Carnegie Institute, Pittsburgh)
Pearsonian correlation matrix was computed on the basis of the 496 estimates made by each I. This matrix was then factor analyzed and three factors were extracted. The first factor accounted for 41% of the interjudge variance and seven of the judges loaded highly on it (loadings of .5 or higher). The second factor accounted for 11% and had high loadings from two of the remaining judges. The final factor accounted for 10% of the variance and the remaining judge loaded greater than .5 on it. Since it appeared that the 10 Is did not exhibit a single judgmental approach, only the seven Js.with high loadings on the first factor were included in the subsequent analysis. The 496 judgments of each J were averaged across the
j. R. ANTES &
890
L. A. STONE
seven Is and cast into a 32 X 32 full symmetric matrix of mean estimates of similarity. Consistent with the method of Stone and Coles (1970), the columns of this mean similarity matrix were intercorrelated to produce a new 32 X 32 matrix of correlational similarities. The matrix was then factor analyzed with the limiting eigenvalue set at 1.0. Five orthogonal judgment factors were extracted and rotated to a varimax criterion. These five rotated factors, shown with factor loadings in Table 1, accounted for 86% of the common variance of the mean estimations of similarity. The factor loadings on each factor were examined to determine if the psyTABLE 1 ROTATEDJUDGMENTAL DIMENSIONS ~~ATRIX Picture Section
1 2 3 4 5 G 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 %
u'
accounted for
I
I1
.90 .92 .95 .91 .92 .93 .92 .49 .20 -.58 -.GO -.03 -.44 .38 -.59 -.I5 .07 -.53 -.30 -.61 -.GO -.27 -.61 -.35 -.I2 -.I3 -.63 -.04 -.66 -.I5 720 -.30 39.9
.15 .13 .08 .lo .13 .09 .15 -.35 .65 .06 .ll .33 .24 .31 .12 .20 -.09 -.59 -.49 -.I4 -.05 .04 -.05 -.I4 -.07 -.08 -.64 .37 -.I5 .19 -.01 .02 23.4
Ill
-.I3 -.lo
-.09 -.I9 -.09 -.lo -.I2 -.09 .23 -.50 -.65 .12 -.I5 -.04 -.49 .12 .01 -.49 -.58 -.I7 -.32 -.08 -.24 .25 .43 .33 -.I7 .82 .01 .91 .91 .85 10.9
IV
V
.29 .27 .23 .29 .27 .26 .30 .41 .12
.04 .08 .OO .06 .02 .09 .02 .51 .31
.Ol
-.GO
.09 -33 -.70 .14 -.40 -.07
-.30 .72 .31 .73 -.07 .87 .91 -.I7 -.I8 -.57 -.GI -.08 -.30 -.I3 .40 .45 -,I6 -.I3 -.57 .06 .05 .18 4.8
.I0
.09 -.07 .15 .I9 -.83 -.54 -.81 -.69 -.68 .12 -.06 .23 -.04 -.I6 -.09 6.6
ha .94 .95 .98 .96 .94 .96 .98 .80 .63 .95 .89 .75 .86 .80 .78 .83 .84 .91 .71 .77 .87 .78 .8 1 .88 .84 .79 .87 .83 .84 .90 .90 .85 86
SCALING OF PICTORIAL INFORMATIVENESS
891
chological nature of each dimension could be readily labeled or reified. T o aid this identification process and to relate the extracted dimensions to behavior the factor loadings were correlated with density of eye-fixations, mean duration of eye fixation and individual ratings of informativeness for each segment of this picture, previously obtained from another sample of Ss (Antes, 1973). These correlations are displayed in Table 2.
TABLE 2 CORRELATIONS OF FACTOR LOADINGSWITH DATAFROMANTES (1973) Factor
Density of Eye-fixation
I 11 111
-.20 .23 -.44* -.24 .23
IV V
*p
< .05.
tp
Duration per Eye-fixation -. 16 -.35* -.47
.15 -.I4
t
Rating of Informativeness -.70t -.23 -.46t
-.39* -.I5
< .01.
Factor I, accounting for 39.9% of the variance following rotation, was apparently a bipolar dimension which was tentatively labeled presence vs absence of information. Receiving positive loadings were segments containing sky or objects in the background with few identifiable features. Sections containing elements which were more readily identifiable and more clearly conveying information received negative loadings. As might be expected, the factor loadings on this dimension correlated highly with informativeness ratings of the picture segments (Table 2 ) . Also, the segments having negative factor loadings tended to receive the greater density of eye fixations and greater average duration per eye fixation, however these relationships did not reach statistical significance. Factor I1 accounted for 23.4% of the judgmental variance following totation. Loadings on this dimension were seemingly related to location of the segments and was labeled as left vs right. Receiving the highest positive loading was section 9, on the left border of the picture, while sections 18, 19, and 27, which form the right border, received the highest negative loadings. The point-biserial correlation between factor loadings and section location (left vs right) was .50 ( p < .01). Table 2 shows that, when correlated with the data from Antes (1973), loadings on this dimension were unrelated to density of eye-fixations or ratings of informativeness, however displayed a slight relationship with duration of fixation. Mean duration for *eye-fixations tended to be higher for sections with negative loadings, in general, those on the right side of the picture. Factor-dimension I11 accounted for 10.9% of the mean similarity variance following rotation and was labeled meaningfulness. Of those segments with
892
J. R. ANTES
&
L. A. STONE
readily identifiable features (and receiving negative loadings on Factor I ) , those segments clearly conveying meaning regarding understanding of the picture (Sections 10, 11, 15, 18, and 19) received the highest negative loadings. Receiving high positive loadings were those segments with identifiable features which were apparently unrelated to understanding the meaning of the picture (Sections 28, 30, 31, and 32). "Meaningful" segments (negative loadings) received a higher density of fixation, greater duration per fixation and higher ratings of informativeness than segments with positive loadings (Table 2 ) . Dimension IV, accounting for 6.6% of the judgmental variance following rotation, was apparently another location dimension and was tentatively labeled inner vs outer. High negative loadings were received by those segments in the center part of the picture (Sections 13, 22, 23, 24, 25, and 26). The pointbiserial correlation between factor loadings and location (border segment vs non-border segment) was .52 ( p < .01). Although unrelated to density or duration of eye-fixations, this factor bore a slight relationship to ratings of informativeness. Center sections (negative loadings) were rated more highly informative than sections with positive factor loadings. Factor V accounted for 4.8% of the mean similarity variance. This dimension also was apparently related to pictorial location and was labeled foreground us background. Sections whose elements were clearly in the foreground of the picture (numbers 10, 20, 21 and 29) received high negative loadings. Sections which formed the horizon of the picture (12, 14, 16 and 17) received high positive loadings. Factor loadings did not significantly correlate with density of eye-fixations, duration of eye-fixations, or ratings of informativeness of Antes (1973). These five factors seemed to be readily interpretable and collectively they accounted for 86% of the mean common variance of the similarity estimations. Factors I and 111 were apparently related to content of the picture and the other three factors were related to physical location within the picture. In this regard it is interesting to note that Schissler (1969) reported no difference in ratings of picture-informativeness if the intact picture was viewed or not viewed prior to rating individual pieces. In the present experiment, had the Js not viewed the intact picture and had rated pairs of sections individually then only minimal location information would have been available and presumably Factors 11, IV and V would not have emerged. As Table 2 suggests, however, the clearest relationship to informativeness ratings is with the "picture content" factors ( I and III), implying that, while similarity judgments may be based on content and location, ratings of informativeness are based primarily on the presence of identifiable features and the meaningfulness of these elements. By far the strongest relationship to visual exploratory behavior (density and duration of eye-fixations) was with Factor 111 labeled meaningfulness. Sig-
SCALING OF PICTORIAL INFORMATIVENESS
893
nificant correlations should have been expected with Factor I; however, such were not obtained. This might be due to the negative loadings of Factor I (information present) not showing sufficient variability necessary to be sensitive to variation in eye-fixations. This experiment has demonstrated the potential fruitfulness of multidimensional scaling methods in examining dimensions used in the judgment of pictorial informativeness. I t should be noted that, although the Stone-Coles method was the multidimensional scaling procedure employed, this particular method has a history of producing judgmental analyses very similar to those produced by other well known "distance" methods (cf. Stone, 1971b; Stone & Coles, 1971). Five readily identifiable factors were extracted which were related to other independently determined measures of informativeness and visual exploration. It remains a task for future research to determine the relationship of the presently extracted kinds of dimensions to other methods of rating informativeness (see Schissler, 1969) and other picture stimuli. REFERENCES ANTES, J. R. Eye fixations as a function of informativeness. Unpublished doctoral dissertation. Iowa State Univer.. 1973. ANTES,J. R. The time course of picture viewing. Journal o f Experimental Psychology, 1974, 103, 62-70. A'ITNEAVE,F., & ARNOULT, M. D. The quantitative study of shape and pattern discrimination. Psychological Bulletin, 1956, 53, 452-47 1. COLES,G . J.. & STONE,L. A. A new methodological revision of Ekman's "content" model of multidimensional similarity analysis. Multivariate Behavioral Resemch, 1972, 7, 85-107. EKMAN,G. Dimensions of color vision. Jorirnul o f Psychology, 1954, 38, 467-474. EKMAN. G. TWOmethods for the analysis of percepmal dimensionality. Psrceptual and Motor Skills, 1965, 20, 557-572. MACKWORTH, N. H., & MORANDI, A. J. The gaze selects informative derails within pictures. Perception d Psychophysics, 1967, 2, 547-551. POLLACK, I., & SPENCE, D. Subjective pictorial information and visual search. Perception & Psychophysicr, 1968, 3, 41-44. SCHISSLER, D. R. Analysis of piccures by subjective ratings and by eye fixations. journal o f General Psychology, 1969, 81, 83-94. STONE,L. A. Congruent multidimensional scaling results obtained using the halo-model and the Stone-Coles method-model. Perceptual and Motor Skills, 1971. 33, 525526. STONE,L. A,. & COLES,G. J. Correlational similarity: the basis for a new revised method of similarity analysis. Studia Psychologica (Bsatislava), 1970, 12, 258264. STONE, L. A., & COLES,G. J. Dimensions of color revisited. Journal o f Psychology, 1971, 77, 79-87. ( a ) STONE,L. A., & COLES,G. J. Psychology graduate students' multidimensional perceptions of their psychology faculty. Acta Psychologica, 1971, 35, 364-377. ( b ) STONE,L. A., COLES,G. J., & LINDEM,A. C. Multidimensional evaluation structure analysis ( M E S A ) : a complete scaling system usable for a multiplicity of purposes. Grand Forks, N . D.: Judgmetrics, 1970.
Accepted Mmch 25, 1975.
