Abstract

A contact-lens technique was used to record eye movements made by two subjects attempting to maintain fixation at the center of concentric round targets of several sizes (1.9′–87.2′ diam) and luminances (2.8, 7.8, and 21.5 mL). Fixation of red, blue, and white 1.9′-diam targets was also examined. Analysis-of-variance designs were employed to remove variability arising from sources other than these stimulus variables. Statistically reliable differences in mean fixation position were found with targets of different size, luminance, and color. The largest difference observed was less than 4′ and under most conditions was less than 2′. The bivariate dispersion of the eye about its mean position varied in a complex manner with the size and luminance of the target object. No statistically reliable effects of stimulus variables were found on drifts. Saccade frequency was considerably reduced with the largest targets. Results are discussed in terms of a “fixed error-signal system” for the control of eye position.

© 1965 Optical Society of America

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References

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  1. T. N. Cornsweet, J. Opt. Soc. Am. 46, 987 (1956).
    [CrossRef] [PubMed]
  2. J. Nachmias, J. Opt. Soc. Am. 49, 901 (1959).
    [CrossRef] [PubMed]
  3. J. Nachmias, J. Opt. Soc. Am. 51, 761 (1961).
    [CrossRef] [PubMed]
  4. K. Gaarder, Science 132, 471 (1960).
    [CrossRef] [PubMed]
  5. D. H. Fender, Brit. J. Ophthalmol. 39, 294 (1955).
    [CrossRef]
  6. F. Ratliff and L. A. Riggs, J. Exptl. Psychol. 40, 687 (1950).
    [CrossRef]
  7. R. W. Ditchburn and B. L. Ginsborg, J. Physiol. 119, 1 (1953).
  8. Approximately 6% of the records were measured twice. The second measurements were made throughout the several months of film reading without access to prior data. The variance attributable to measurement error is: SF, 0.074 saccades; mean horizontal position, 0.049′; mean vertical position, 0.012′; DM, 0.087′, and logAp, 0.001 (min arc)2.
  9. To illustrate, the standard deviation of the horizontal component of rotation might not be affected by changes in luminance while along some other meridian large effects do, in fact, occur. Since such directional nonuniformitics along various meridians within and between individuals have been shown, a measure of dispersion which includes all directions of rotation was used.2,3An alternative approach would be to find the meridian along which maximum and minimum treatment effects do occur for each subject.
  10. W. Cochran and G. Cox, Experimental Designs (John Wiley & Sons, Inc., New York, 1957).
  11. These effects could be of two kinds: a somewhat mysterious effect of after-images of small targets which aids in the fixation of larger ones; or practice effects, relatively stable fixation of large targets requiring periodic trials with smaller ones.
  12. See R. M. Steinman, Ph.D. dissertation (University Microfilms, Ann Arbor, Michigan, 1964) for the complete analyses of variance and tabled data.
  13. J. Krauskopf, T. N. Cornsweet, and L. A. Riggs, J. Opt. Soc. Am. 50, 572 (1960).
    [CrossRef] [PubMed]
  14. “Local sign” refers only to a signal which can be used to guide the direction and size of corrective eye movements. Such “motor local signs” may be related to other “local signs” which lead to the perceived direction or movement of an object in space relative to the observer. See J. Bruel and G. Albee, Psychol. Rev. 62, 391 (1955) for a discussion of the possible relationship of eye position and eye movements to the perception of direction and movement.
    [CrossRef]
  15. S. L. Polyak, The Retina (The Universitv of Chicago Press, Chicago, 1941).

1961 (1)

1960 (2)

1959 (1)

1956 (1)

1955 (2)

“Local sign” refers only to a signal which can be used to guide the direction and size of corrective eye movements. Such “motor local signs” may be related to other “local signs” which lead to the perceived direction or movement of an object in space relative to the observer. See J. Bruel and G. Albee, Psychol. Rev. 62, 391 (1955) for a discussion of the possible relationship of eye position and eye movements to the perception of direction and movement.
[CrossRef]

D. H. Fender, Brit. J. Ophthalmol. 39, 294 (1955).
[CrossRef]

1953 (1)

R. W. Ditchburn and B. L. Ginsborg, J. Physiol. 119, 1 (1953).

1950 (1)

F. Ratliff and L. A. Riggs, J. Exptl. Psychol. 40, 687 (1950).
[CrossRef]

Albee, G.

“Local sign” refers only to a signal which can be used to guide the direction and size of corrective eye movements. Such “motor local signs” may be related to other “local signs” which lead to the perceived direction or movement of an object in space relative to the observer. See J. Bruel and G. Albee, Psychol. Rev. 62, 391 (1955) for a discussion of the possible relationship of eye position and eye movements to the perception of direction and movement.
[CrossRef]

Bruel, J.

“Local sign” refers only to a signal which can be used to guide the direction and size of corrective eye movements. Such “motor local signs” may be related to other “local signs” which lead to the perceived direction or movement of an object in space relative to the observer. See J. Bruel and G. Albee, Psychol. Rev. 62, 391 (1955) for a discussion of the possible relationship of eye position and eye movements to the perception of direction and movement.
[CrossRef]

Cochran, W.

W. Cochran and G. Cox, Experimental Designs (John Wiley & Sons, Inc., New York, 1957).

Cornsweet, T. N.

Cox, G.

W. Cochran and G. Cox, Experimental Designs (John Wiley & Sons, Inc., New York, 1957).

Ditchburn, R. W.

R. W. Ditchburn and B. L. Ginsborg, J. Physiol. 119, 1 (1953).

Fender, D. H.

D. H. Fender, Brit. J. Ophthalmol. 39, 294 (1955).
[CrossRef]

Gaarder, K.

K. Gaarder, Science 132, 471 (1960).
[CrossRef] [PubMed]

Ginsborg, B. L.

R. W. Ditchburn and B. L. Ginsborg, J. Physiol. 119, 1 (1953).

Krauskopf, J.

Nachmias, J.

Polyak, S. L.

S. L. Polyak, The Retina (The Universitv of Chicago Press, Chicago, 1941).

Ratliff, F.

F. Ratliff and L. A. Riggs, J. Exptl. Psychol. 40, 687 (1950).
[CrossRef]

Riggs, L. A.

Steinman, R. M.

See R. M. Steinman, Ph.D. dissertation (University Microfilms, Ann Arbor, Michigan, 1964) for the complete analyses of variance and tabled data.

Brit. J. Ophthalmol. (1)

D. H. Fender, Brit. J. Ophthalmol. 39, 294 (1955).
[CrossRef]

J. Exptl. Psychol. (1)

F. Ratliff and L. A. Riggs, J. Exptl. Psychol. 40, 687 (1950).
[CrossRef]

J. Opt. Soc. Am. (4)

J. Physiol. (1)

R. W. Ditchburn and B. L. Ginsborg, J. Physiol. 119, 1 (1953).

Psychol. Rev. (1)

“Local sign” refers only to a signal which can be used to guide the direction and size of corrective eye movements. Such “motor local signs” may be related to other “local signs” which lead to the perceived direction or movement of an object in space relative to the observer. See J. Bruel and G. Albee, Psychol. Rev. 62, 391 (1955) for a discussion of the possible relationship of eye position and eye movements to the perception of direction and movement.
[CrossRef]

Science (1)

K. Gaarder, Science 132, 471 (1960).
[CrossRef] [PubMed]

Other (6)

S. L. Polyak, The Retina (The Universitv of Chicago Press, Chicago, 1941).

Approximately 6% of the records were measured twice. The second measurements were made throughout the several months of film reading without access to prior data. The variance attributable to measurement error is: SF, 0.074 saccades; mean horizontal position, 0.049′; mean vertical position, 0.012′; DM, 0.087′, and logAp, 0.001 (min arc)2.

To illustrate, the standard deviation of the horizontal component of rotation might not be affected by changes in luminance while along some other meridian large effects do, in fact, occur. Since such directional nonuniformitics along various meridians within and between individuals have been shown, a measure of dispersion which includes all directions of rotation was used.2,3An alternative approach would be to find the meridian along which maximum and minimum treatment effects do occur for each subject.

W. Cochran and G. Cox, Experimental Designs (John Wiley & Sons, Inc., New York, 1957).

These effects could be of two kinds: a somewhat mysterious effect of after-images of small targets which aids in the fixation of larger ones; or practice effects, relatively stable fixation of large targets requiring periodic trials with smaller ones.

See R. M. Steinman, Ph.D. dissertation (University Microfilms, Ann Arbor, Michigan, 1964) for the complete analyses of variance and tabled data.

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Figures (5)

F. 1
F. 1

Schematic diagram of the fixation (dashed line) and recording (solid lines) apparatus. S1 and 2 recording and fixation sources; L1–5 lenses; SA and WA apertures; TA automatic device for changing target apertures; CA and NDA automatic devices for changing color and neutral density filters; M1–4 first-surface mirrors; CLM small first-surface mirror attached to a contact lens worn on the right eye RE; P circular polarizer; O opal diffuser; SH shutter. The insert shows the image of WA on a horizontal slit in front of the film. The arrow indicates the direction of film motion.

F. 2
F. 2

Mean bivariate dispersion (logAp) as a function of the logarithm of the area of the fixation target averaged over three luminance levels. The line connects the five data points from Experiment 1 where target size was the within-session variable. Squares enclose points from Experiment 2 where only three target sizes were employed, each at different recording sessions. Circles enclose points from Experiment 3 where red (R), blue (B), and white (W) 1.9′-diam targets were presented 8 dB above a 100% visibility threshold. The crosses are for subject RS; the filled circles, subject MH.

F. 3
F. 3

Mean bivariate dispersion (logAp) as a function of the luminance of the fixation target (log mL), averaged over three target sizes (1.9′, 27.9′, and 87.2′ diam). The line connects the data points from Experiment 2 where luminance was the within-session variable. Points from Experiment 1 for the same size targets are also plotted. Experimental luminances were 2.8, 7.8, and 21.5 mL.

F. 4
F. 4

Mean saccade frequency (SF) as a function of the logarithm of the area of the fixation target (logAT) averaged over three luminance levels. The significance of the symbols is the same as in Fig. 2.

F. 5
F. 5

Cumulative percentage (%) of normalized position vectors of different vector magnitudes (2k). Bivariate normal, solid curve. See Sec. 3.3 for an explanation of this graph.

Tables (4)

Tables Icon

Table I Means of the relative horizontal (H) and vertical (V) trial mean fixation positions in minutes of arc. The negative signs indicate that the mean position of the eye was to the right on the horizontal component or above on the vertical component relative to the smallest, least luminous, and white target in Experiments 1, 2, and 3, respectively. The targets were concentric to less than 1′.

Tables Icon

Table II Partial summary of the analyses of variance of horizontal (H) and vertical (V) trial mean position.

Tables Icon

Table III Partial summary of the analyses of variance of bivariate dispersion (logAp).

Tables Icon

Table IV Partial summary of the analyses of variance of saccade frequency (SF).

Equations (2)

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A = 2 k σ H σ V ( 1 ρ 2 ) 1 2
P = 1 e k ,