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<meta name="robots" content="INDEX,FOLLOW,NOARCHIVE" /><meta name="citation_inbook_title" content="Webvision: The Organization of the Retina and Visual System [Internet]" /><meta name="citation_title" content="The Perception of Space" /><meta name="citation_publisher" content="University of Utah Health Sciences Center" /><meta name="citation_date" content="2007/06/06" /><meta name="citation_author" content="Michael Kalloniatis" /><meta name="citation_author" content="Charles Luu" /><meta name="citation_pmid" content="21413400" /><meta name="citation_fulltext_html_url" content="https://www.ncbi.nlm.nih.gov/books/NBK11545/" /><link rel="schema.DC" href="http://purl.org/DC/elements/1.0/" /><meta name="DC.Title" content="The Perception of Space" /><meta name="DC.Type" content="Text" /><meta name="DC.Publisher" content="University of Utah Health Sciences Center" /><meta name="DC.Contributor" content="Michael Kalloniatis" /><meta name="DC.Contributor" content="Charles Luu" /><meta name="DC.Date" content="2007/06/06" /><meta name="DC.Identifier" content="https://www.ncbi.nlm.nih.gov/books/NBK11545/" /><meta name="description" content="When we look at an object with two eyes, we perceive it as singular, like we do other parts of the visual scene stimulating points on our retina that share a common visual direction. These points are termed "retinal corresponding points" and fall on an area called the "horopter". Points outside the horopter fall on slightly different retinal areas and so do not have the identical visual direction and lead to "retinal disparity", the basis of our depth discrimination. This retinal image disparity occurs due to the lateral displacement of the eyes. The region in visual space over which we perceive single vision is known as "Panum's fusional area", with objects in front and behind this area being in physiological diplopia (i.e., double vision). Our visual system suppresses this diplopia, and hence we do not perceive double vision under normal viewing conditions. To understand the discussion on the horopter and Panum's fusional space, the sense of direction will be introduced. 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Our visual system suppresses this diplopia, and hence we do not perceive double vision under normal viewing conditions. To understand the discussion on the horopter and Panum's fusional space, the sense of direction will be introduced. 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<div class="pre-content"><div><div class="bk_prnt"><p class="small">NCBI Bookshelf. A service of the National Library of Medicine, National Institutes of Health.</p><p>Kolb H, Fernandez E, Jones B, et al., editors. Webvision: The Organization of the Retina and Visual System [Internet]. Salt Lake City (UT): University of Utah Health Sciences Center; 1995-. </p></div><div class="iconblock clearfix whole_rhythm no_top_margin bk_noprnt"><a class="img_link icnblk_img" title="Table of Contents Page" href="/books/n/webvision/"><img class="source-thumb" src="/corehtml/pmc/pmcgifs/bookshelf/thumbs/th-webvision-lrg.png" alt="Cover of Webvision" height="100px" width="80px" /></a><div class="icnblk_cntnt eight_col"><h2>Webvision: The Organization of the Retina and Visual System [Internet].</h2><a data-jig="ncbitoggler" href="#__NBK11545_dtls__">Show details</a><div style="display:none" class="ui-widget" id="__NBK11545_dtls__"><div>Kolb H, Fernandez E, Jones B, et al., editors.</div><div>Salt Lake City (UT): <a href="http://webvision.med.utah.edu/" ref="pagearea=page-banner&targetsite=external&targetcat=link&targettype=publisher">University of Utah Health Sciences Center</a>; 1995-.</div></div><div class="half_rhythm"><ul class="inline_list"><li style="margin-right:1em"><a class="bk_cntns" href="/books/n/webvision/">Contents</a></li></ul></div><div class="bk_noprnt"><form method="get" action="/books/n/webvision/" id="bk_srch"><div class="bk_search"><label for="bk_term" class="offscreen_noflow">Search term</label><input type="text" title="Search this book" id="bk_term" name="term" value="" data-jig="ncbiclearbutton" /> <input type="submit" class="jig-ncbibutton" value="Search this book" submit="false" style="padding: 0.1em 0.4em;" /></div></form></div></div><div class="icnblk_cntnt two_col"><div class="pagination bk_noprnt"><a class="active page_link prev" href="/books/n/webvision/ch28kallcolor/" title="Previous page in this title">< Prev</a><a class="active page_link next" href="/books/n/webvision/ch30kalldepth/" title="Next page in this title">Next ></a></div></div></div></div></div>
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<div class="main-content lit-style" itemscope="itemscope" itemtype="http://schema.org/CreativeWork"><div class="meta-content fm-sec"><h1 id="_NBK11545_"><span class="title" itemprop="name">The Perception of Space</span></h1><p class="contrib-group"><span itemprop="author">Michael Kalloniatis</span> and <span itemprop="author">Charles Luu</span>.</p><a data-jig="ncbitoggler" href="#__NBK11545_ai__" style="border:0;text-decoration:none">Author Information and Affiliations</a><div style="display:none" class="ui-widget" id="__NBK11545_ai__"><p class="contrib-group"><h4>Authors</h4><span itemprop="author">Michael Kalloniatis</span> and <span itemprop="author">Charles Luu</span>.</p><h4>Affiliations</h4><div class="affiliation"><sup>1</sup>
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Department of Optometry and Vision Sciences University of Melbourne,
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Australia
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</div></div><p class="small">Created: <span itemprop="datePublished">May 1, 2005</span>; Last Update: <span itemprop="dateModified">June 6, 2007</span>.</p></div><div class="jig-ncbiinpagenav body-content whole_rhythm" data-jigconfig="allHeadingLevels: ['h2'],smoothScroll: false" itemprop="text"><div id="ch29space_perceptio.Retinal_Disparity"><h2 id="_ch29space_perceptio_Retinal_Disparity_">Retinal Disparity</h2><p>When we look at an object with two eyes, we perceive it as singular, like we do other
|
|
parts of the visual scene stimulating points on our retina that share a common
|
|
visual direction. These points are termed "retinal corresponding points" and fall on
|
|
an area called the "horopter". Points outside the horopter fall on slightly
|
|
different retinal areas and so do not have the identical visual direction and lead
|
|
to "retinal disparity", the basis of our depth discrimination. This retinal image
|
|
disparity occurs due to the lateral displacement of the eyes. The region in visual
|
|
space over which we perceive single vision is known as "Panum's fusional area", with
|
|
objects in front and behind this area being in physiological diplopia (i.e., double
|
|
vision). Our visual system suppresses this diplopia, and hence we do not perceive
|
|
double vision under normal viewing conditions. To understand the discussion on the
|
|
horopter and Panum's fusional space, the sense of direction will be introduced. Two
|
|
terms describing direction sense are oculocentric and egocentric visual
|
|
direction.</p><div id="ch29space_perceptio.Oculocentric_Visual_"><h3>Oculocentric Visual Direction</h3><p>The visual direction of an object can be represented by a line that joins the
|
|
object and the fovea called the Principal Visual Direction or visual axis. On
|
|
the basis of the principal visual direction, the direction of all other objects
|
|
in the subject's visual field is determined. This is the called oculocentric
|
|
visual direction. Therefore, each point of the retina can be considered to have
|
|
it own sense of direction. For example, when we look at an object, the object is
|
|
imaged on the fovea. Other objects imaged above the fovea are seen as "below",
|
|
and those imaged below the fovea are seen as "above". Visual sense of direction
|
|
is organized about the fovea. For a given position of the eye, objects having
|
|
superimposed retinal images will be seen as being in alignment in the visual
|
|
field, but at a different distance from the eye (<a class="figpopup" href="/books/NBK11545/figure/ch29space_perceptio.F1/?report=objectonly" target="object" rid-figpopup="figch29spaceperceptioF1" rid-ob="figobch29spaceperceptioF1">Fig.
|
|
1</a>).</p><div class="iconblock whole_rhythm clearfix ten_col fig" id="figch29spaceperceptioF1" co-legend-rid="figlgndch29spaceperceptioF1"><a href="/books/NBK11545/figure/ch29space_perceptio.F1/?report=objectonly" target="object" title="Figure 1" class="img_link icnblk_img figpopup" rid-figpopup="figch29spaceperceptioF1" rid-ob="figobch29spaceperceptioF1"><img class="small-thumb" src="/books/NBK11545/bin/space_perceptionf1.gif" src-large="/books/NBK11545/bin/space_perceptionf1.jpg" alt="Figure 1. Oculocentric visual direction." /></a><div class="icnblk_cntnt" id="figlgndch29spaceperceptioF1"><h4 id="ch29space_perceptio.F1"><a href="/books/NBK11545/figure/ch29space_perceptio.F1/?report=objectonly" target="object" rid-ob="figobch29spaceperceptioF1">Figure 1</a></h4><p class="float-caption no_bottom_margin">Oculocentric visual direction. </p></div></div></div><div id="ch29space_perceptio.Egocentric_Visual_Di"><h3>Egocentric Visual Direction</h3><p>Egocentric visual direction refers to the direction of an object in space
|
|
relative to one self, rather than the eyes. Egocentric direction is determined
|
|
by retinal position, proprioceptive information about the eye, head and body
|
|
position, and the vestibular apparatus. All this information allows us to
|
|
determine whether a change in retinal position is due to object movement or due
|
|
to eye or head movement. In <a class="figpopup" href="/books/NBK11545/figure/ch29space_perceptio.F2/?report=objectonly" target="object" rid-figpopup="figch29spaceperceptioF2" rid-ob="figobch29spaceperceptioF2">Fig. 2</a>a, a stationary object is
|
|
imaged on the fovea with the head and the body stationary. When the eye moves,
|
|
the stationary object is then imaged on a new retinal position. Therefore,
|
|
oculocentric direction has changed, but the egocentric direction has not changed
|
|
as the object has remained stationary. In another example, the eye tracks a
|
|
moving object (<a class="figpopup" href="/books/NBK11545/figure/ch29space_perceptio.F2/?report=objectonly" target="object" rid-figpopup="figch29spaceperceptioF2" rid-ob="figobch29spaceperceptioF2">Fig.
|
|
2</a>b). As the object is imaged on the fovea at all times, the oculocentric
|
|
direction is the same, but the egocentric direction is changing.</p><div class="iconblock whole_rhythm clearfix ten_col fig" id="figch29spaceperceptioF2" co-legend-rid="figlgndch29spaceperceptioF2"><a href="/books/NBK11545/figure/ch29space_perceptio.F2/?report=objectonly" target="object" title="Figure 2" class="img_link icnblk_img figpopup" rid-figpopup="figch29spaceperceptioF2" rid-ob="figobch29spaceperceptioF2"><img class="small-thumb" src="/books/NBK11545/bin/space_perceptionf2.gif" src-large="/books/NBK11545/bin/space_perceptionf2.jpg" alt="Figure 2. (a) Different oculocentric direction but the same egocentric direction as the object is stationary." /></a><div class="icnblk_cntnt" id="figlgndch29spaceperceptioF2"><h4 id="ch29space_perceptio.F2"><a href="/books/NBK11545/figure/ch29space_perceptio.F2/?report=objectonly" target="object" rid-ob="figobch29spaceperceptioF2">Figure 2</a></h4><p class="float-caption no_bottom_margin">(a) Different oculocentric direction but the same egocentric
|
|
direction as the object is stationary. (b) Same oculocentric direction but
|
|
egocentric direction is changing because the object is moving. </p></div></div><p>In binocular vision, the idea of corresponding retinal points has been used to
|
|
describe the principle visual direction. Corresponding retinal points are points
|
|
stimulated on the retina that give rise to the same visual direction. When
|
|
objects stimulate non-corresponding points, this gives rise to different visual
|
|
directions. These retinal points are called disparate points. Therefore,
|
|
corresponding points have the same principle visual direction, and
|
|
non-corresponding points have different visual directions (<a class="figpopup" href="/books/NBK11545/figure/ch29space_perceptio.F3/?report=objectonly" target="object" rid-figpopup="figch29spaceperceptioF3" rid-ob="figobch29spaceperceptioF3">Fig.
|
|
3</a>).</p><div class="iconblock whole_rhythm clearfix ten_col fig" id="figch29spaceperceptioF3" co-legend-rid="figlgndch29spaceperceptioF3"><a href="/books/NBK11545/figure/ch29space_perceptio.F3/?report=objectonly" target="object" title="Figure 3" class="img_link icnblk_img figpopup" rid-figpopup="figch29spaceperceptioF3" rid-ob="figobch29spaceperceptioF3"><img class="small-thumb" src="/books/NBK11545/bin/space_perceptionf3.gif" src-large="/books/NBK11545/bin/space_perceptionf3.jpg" alt="Figure 3. Corresponding points of the two eyes." /></a><div class="icnblk_cntnt" id="figlgndch29spaceperceptioF3"><h4 id="ch29space_perceptio.F3"><a href="/books/NBK11545/figure/ch29space_perceptio.F3/?report=objectonly" target="object" rid-ob="figobch29spaceperceptioF3">Figure 3</a></h4><p class="float-caption no_bottom_margin">Corresponding points of the two eyes. </p></div></div><p>As we see the world single and not double, binocular vision can be represented by
|
|
a single eye, the cyclopean eye. The cyclopean eye is an imaginary eye situated
|
|
midway between the two eyes (<a class="figpopup" href="/books/NBK11545/figure/ch29space_perceptio.F4/?report=objectonly" target="object" rid-figpopup="figch29spaceperceptioF4" rid-ob="figobch29spaceperceptioF4">Fig. 4</a>). Disparate points give
|
|
rise to physiological diplopia (double vision). In <a class="figpopup" href="/books/NBK11545/figure/ch29space_perceptio.F5/?report=objectonly" target="object" rid-figpopup="figch29spaceperceptioF5" rid-ob="figobch29spaceperceptioF5">Fig.
|
|
5</a>, it can be seen that point A stimulates disparate points
|
|
(non-corresponding retinal points).</p><div class="iconblock whole_rhythm clearfix ten_col fig" id="figch29spaceperceptioF4" co-legend-rid="figlgndch29spaceperceptioF4"><a href="/books/NBK11545/figure/ch29space_perceptio.F4/?report=objectonly" target="object" title="Figure 4" class="img_link icnblk_img figpopup" rid-figpopup="figch29spaceperceptioF4" rid-ob="figobch29spaceperceptioF4"><img class="small-thumb" src="/books/NBK11545/bin/space_perceptionf4.gif" src-large="/books/NBK11545/bin/space_perceptionf4.jpg" alt="Figure 4. The cyclopean eye is used to determine the direction of point A and point B." /></a><div class="icnblk_cntnt" id="figlgndch29spaceperceptioF4"><h4 id="ch29space_perceptio.F4"><a href="/books/NBK11545/figure/ch29space_perceptio.F4/?report=objectonly" target="object" rid-ob="figobch29spaceperceptioF4">Figure 4</a></h4><p class="float-caption no_bottom_margin">The cyclopean eye is used to determine the direction of point A and
|
|
point B. Point A stimulating the temporal retina of right eye and the nasal
|
|
retina of the left eye, that is, stimulates a retinal point to the right of
|
|
the fovea. </p></div></div><div class="iconblock whole_rhythm clearfix ten_col fig" id="figch29spaceperceptioF5" co-legend-rid="figlgndch29spaceperceptioF5"><a href="/books/NBK11545/figure/ch29space_perceptio.F5/?report=objectonly" target="object" title="Figure 5" class="img_link icnblk_img figpopup" rid-figpopup="figch29spaceperceptioF5" rid-ob="figobch29spaceperceptioF5"><img class="small-thumb" src="/books/NBK11545/bin/space_perceptionf5.gif" src-large="/books/NBK11545/bin/space_perceptionf5.jpg" alt="Figure 5. Point A and point B stimulating disparate points." /></a><div class="icnblk_cntnt" id="figlgndch29spaceperceptioF5"><h4 id="ch29space_perceptio.F5"><a href="/books/NBK11545/figure/ch29space_perceptio.F5/?report=objectonly" target="object" rid-ob="figobch29spaceperceptioF5">Figure 5</a></h4><p class="float-caption no_bottom_margin">Point A and point B stimulating disparate points. Point A
|
|
stimulates the nasal retina of both eyes. </p></div></div><p>Using the cyclopean eye, crossed and uncrossed diplopia can be explored. For an
|
|
object closer than the fixation point such as point B in <a class="figpopup" href="/books/NBK11545/figure/ch29space_perceptio.F6/?report=objectonly" target="object" rid-figpopup="figch29spaceperceptioF6" rid-ob="figobch29spaceperceptioF6">Fig.
|
|
6</a>a, crossed diplopia occurs as the point B is imaged on the temporal
|
|
retina of both eyes. This is termed crossed diplopia because the image in the
|
|
left eye is seen on the right side. For an object located further than the
|
|
fixation point, the image of the object falls on the nasal retina of both eyes,
|
|
producing uncrossed diplopia. This is termed uncrossed diplopia because the
|
|
image in the left eye is seen on the left side (<a class="figpopup" href="/books/NBK11545/figure/ch29space_perceptio.F6/?report=objectonly" target="object" rid-figpopup="figch29spaceperceptioF6" rid-ob="figobch29spaceperceptioF6">Fig. 6</a>b).</p><div class="iconblock whole_rhythm clearfix ten_col fig" id="figch29spaceperceptioF6" co-legend-rid="figlgndch29spaceperceptioF6"><a href="/books/NBK11545/figure/ch29space_perceptio.F6/?report=objectonly" target="object" title="Figure 6" class="img_link icnblk_img figpopup" rid-figpopup="figch29spaceperceptioF6" rid-ob="figobch29spaceperceptioF6"><img class="small-thumb" src="/books/NBK11545/bin/space_perceptionf6.gif" src-large="/books/NBK11545/bin/space_perceptionf6.jpg" alt="Figure 6. Demonstrating crossed (a) and uncrossed (b) diplopia using the cyclopean eye." /></a><div class="icnblk_cntnt" id="figlgndch29spaceperceptioF6"><h4 id="ch29space_perceptio.F6"><a href="/books/NBK11545/figure/ch29space_perceptio.F6/?report=objectonly" target="object" rid-ob="figobch29spaceperceptioF6">Figure 6</a></h4><p class="float-caption no_bottom_margin">Demonstrating crossed (a) and uncrossed (b) diplopia using the
|
|
cyclopean eye. </p></div></div><p>The principle of the cyclopean eye can be applied to patients with strabismus (a
|
|
turned eye). Patients with strabismus are usually classified according to the
|
|
direction of the eye turn. Two common types of strabismus are patients with an
|
|
esotropia, their eye(s) turned in, and patients with exotropia, their eye(s)
|
|
turned out. Patients with an exotropia will have crossed diplopia, whereas
|
|
patients with an esotropia will have uncrossed diplopia (<a class="figpopup" href="/books/NBK11545/figure/ch29space_perceptio.F7/?report=objectonly" target="object" rid-figpopup="figch29spaceperceptioF7" rid-ob="figobch29spaceperceptioF7">Fig.
|
|
7</a>).</p><div class="iconblock whole_rhythm clearfix ten_col fig" id="figch29spaceperceptioF7" co-legend-rid="figlgndch29spaceperceptioF7"><a href="/books/NBK11545/figure/ch29space_perceptio.F7/?report=objectonly" target="object" title="Figure 7" class="img_link icnblk_img figpopup" rid-figpopup="figch29spaceperceptioF7" rid-ob="figobch29spaceperceptioF7"><img class="small-thumb" src="/books/NBK11545/bin/space_perceptionf7.gif" src-large="/books/NBK11545/bin/space_perceptionf7.jpg" alt="Figure 7. (a) Uncrossed diplopia with an esotropia." /></a><div class="icnblk_cntnt" id="figlgndch29spaceperceptioF7"><h4 id="ch29space_perceptio.F7"><a href="/books/NBK11545/figure/ch29space_perceptio.F7/?report=objectonly" target="object" rid-ob="figobch29spaceperceptioF7">Figure 7</a></h4><p class="float-caption no_bottom_margin">(a) Uncrossed diplopia with an esotropia. (b) Crossed diplopia with
|
|
an exotropia. </p></div></div></div></div><div id="ch29space_perceptio.The_Horopter"><h2 id="_ch29space_perceptio_The_Horopter_">The Horopter</h2><p>Our visual world is composed of multiple points, hence the need to develop concepts
|
|
to deal with the whole visual space. This concept is called the horopter. The
|
|
horopter is the locus of points in space that stimulates corresponding points, that
|
|
is, a multitude of points in visual space that lead to single vision.</p><div id="ch29space_perceptio.The_ViethMuller_Circ"><h3>The Vieth-Muller Circle</h3><p>The Vieth-Muller circle is a theoretical horopter. All points on this circle
|
|
should stimulate corresponding points on the retina and lead to single vision,
|
|
provided that the fixation point lies on the center of the circle and the eyes
|
|
rotate about its nodal point (instead of their center of rotation). The
|
|
Vieth-Muller circle assumes there is angular symmetry of the corresponding
|
|
points (<a class="figpopup" href="/books/NBK11545/figure/ch29space_perceptio.F8/?report=objectonly" target="object" rid-figpopup="figch29spaceperceptioF8" rid-ob="figobch29spaceperceptioF8">Fig. 8</a>).</p><div class="iconblock whole_rhythm clearfix ten_col fig" id="figch29spaceperceptioF8" co-legend-rid="figlgndch29spaceperceptioF8"><a href="/books/NBK11545/figure/ch29space_perceptio.F8/?report=objectonly" target="object" title="Figure 8" class="img_link icnblk_img figpopup" rid-figpopup="figch29spaceperceptioF8" rid-ob="figobch29spaceperceptioF8"><img class="small-thumb" src="/books/NBK11545/bin/space_perceptionf8.gif" src-large="/books/NBK11545/bin/space_perceptionf8.jpg" alt="Figure 8. Vieth-Muller circle." /></a><div class="icnblk_cntnt" id="figlgndch29spaceperceptioF8"><h4 id="ch29space_perceptio.F8"><a href="/books/NBK11545/figure/ch29space_perceptio.F8/?report=objectonly" target="object" rid-ob="figobch29spaceperceptioF8">Figure 8</a></h4><p class="float-caption no_bottom_margin">Vieth-Muller circle. The circle represents the theoretical locus of
|
|
points in space that stimulates corresponding retinal points. </p></div></div></div><div id="ch29space_perceptio.Measuring_the_Horopt"><h3>Measuring the Horopter</h3><p>The horopter can be measured through several methods. These methods include:</p><ul><li id="A4186" class="half_rhythm"><div>Haplopic method</div></li><li id="A4187" class="half_rhythm"><div>Nonius method</div></li><li id="A4188" class="half_rhythm"><div>Apparent front-parallel plane (AFPP) method</div></li></ul><p>The Nonius and AFPP methods directly determine the longitudinal horopter, whereas
|
|
the haplopic method does not. Instead, the haplopic method determines the inner
|
|
and outer boundaries of single binocular vision, and the horopter is taken as
|
|
the midline.</p><div id="ch29space_perceptio.Haplopic_Method"><h4>Haplopic Method</h4><p>The haplopic method (method of the region of singular binocular vision) is
|
|
based on the primary definition of corresponding points; retinal points that
|
|
correspond give rise to identical visual directions and, as a consequence,
|
|
single vision. Thus, if diplopia is observed, disparate points are being
|
|
stimulated. Therefore, the method involves determining the boundaries of
|
|
single binocular vision (<a class="figpopup" href="/books/NBK11545/figure/ch29space_perceptio.F9/?report=objectonly" target="object" rid-figpopup="figch29spaceperceptioF9" rid-ob="figobch29spaceperceptioF9">Fig. 9</a>).</p><div class="iconblock whole_rhythm clearfix ten_col fig" id="figch29spaceperceptioF9" co-legend-rid="figlgndch29spaceperceptioF9"><a href="/books/NBK11545/figure/ch29space_perceptio.F9/?report=objectonly" target="object" title="Figure 9" class="img_link icnblk_img figpopup" rid-figpopup="figch29spaceperceptioF9" rid-ob="figobch29spaceperceptioF9"><img class="small-thumb" src="/books/NBK11545/bin/space_perceptionf9.gif" src-large="/books/NBK11545/bin/space_perceptionf9.jpg" alt="Figure 9. Result of the horopter determined by the haplopic method at a viewing distance of 40 cm." /></a><div class="icnblk_cntnt" id="figlgndch29spaceperceptioF9"><h4 id="ch29space_perceptio.F9"><a href="/books/NBK11545/figure/ch29space_perceptio.F9/?report=objectonly" target="object" rid-ob="figobch29spaceperceptioF9">Figure 9</a></h4><p class="float-caption no_bottom_margin">Result of the horopter determined by the haplopic method at a
|
|
viewing distance of 40 cm. From Moses and Hart (1) and Ogle (2). </p></div></div></div><div id="ch29space_perceptio.Nonius_Method"><h4>Nonius Method</h4><p>Because corresponding points give rise to identical visual directions, the
|
|
position of an object that stimulates a pair of corresponding points can be
|
|
located if each eye sees a different part of the object. If the two parts
|
|
are seen in the same direction, then the objects are in that position where
|
|
they stimulate corresponding points. This is the basis of the Nonius method
|
|
(method of equating visual directions) (<a class="figpopup" href="/books/NBK11545/figure/ch29space_perceptio.F10/?report=objectonly" target="object" rid-figpopup="figch29spaceperceptioF10" rid-ob="figobch29spaceperceptioF10">Fig.
|
|
10</a>).</p><div class="iconblock whole_rhythm clearfix ten_col fig" id="figch29spaceperceptioF10" co-legend-rid="figlgndch29spaceperceptioF10"><a href="/books/NBK11545/figure/ch29space_perceptio.F10/?report=objectonly" target="object" title="Figure 10" class="img_link icnblk_img figpopup" rid-figpopup="figch29spaceperceptioF10" rid-ob="figobch29spaceperceptioF10"><img class="small-thumb" src="/books/NBK11545/bin/space_perceptionf10.gif" src-large="/books/NBK11545/bin/space_perceptionf10.jpg" alt="Figure 10. The horopter as determined by the Nonius method." /></a><div class="icnblk_cntnt" id="figlgndch29spaceperceptioF10"><h4 id="ch29space_perceptio.F10"><a href="/books/NBK11545/figure/ch29space_perceptio.F10/?report=objectonly" target="object" rid-ob="figobch29spaceperceptioF10">Figure 10</a></h4><p class="float-caption no_bottom_margin">The horopter as determined by the Nonius method. From Moses and
|
|
Hart (1)
|
|
and Ogle (2). </p></div></div></div><div id="ch29space_perceptio.The_Apparent_FrontoP"><h4>The Apparent Fronto-Parallel Plane (AFPP) Method</h4><p>The theory of stereopsis holds that stimulation of disparate points is
|
|
necessary for the perception of relative depth by stereopsis. If there is no
|
|
depth difference between an object and the fixation point, then they
|
|
stimulate corresponding points. Thus, if the subject is asked to arrange a
|
|
series of objects so that they appear to be in a fronto-parallel plane
|
|
(i.e., no depth difference between them), then they will lie on the
|
|
horopter. This is the apparent fronto-parallel plane method (<a class="figpopup" href="/books/NBK11545/figure/ch29space_perceptio.F11/?report=objectonly" target="object" rid-figpopup="figch29spaceperceptioF11" rid-ob="figobch29spaceperceptioF11">Fig. 11</a>). Note the change in
|
|
shape of the horopter at different distances.</p><div class="iconblock whole_rhythm clearfix ten_col fig" id="figch29spaceperceptioF11" co-legend-rid="figlgndch29spaceperceptioF11"><a href="/books/NBK11545/figure/ch29space_perceptio.F11/?report=objectonly" target="object" title="Figure 11" class="img_link icnblk_img figpopup" rid-figpopup="figch29spaceperceptioF11" rid-ob="figobch29spaceperceptioF11"><img class="small-thumb" src="/books/NBK11545/bin/space_perceptionf11.gif" src-large="/books/NBK11545/bin/space_perceptionf11.jpg" alt="Figure 11. The horopter as determined by the apparent fronto-parallel plane method at different distances (25 cm, 40 cm, and 1 m)." /></a><div class="icnblk_cntnt" id="figlgndch29spaceperceptioF11"><h4 id="ch29space_perceptio.F11"><a href="/books/NBK11545/figure/ch29space_perceptio.F11/?report=objectonly" target="object" rid-ob="figobch29spaceperceptioF11">Figure 11</a></h4><p class="float-caption no_bottom_margin">The horopter as determined by the apparent fronto-parallel plane
|
|
method at different distances (25 cm, 40 cm, and 1 m). From Ogle (2). </p></div></div></div></div><div id="ch29space_perceptio.Relationship_of_the_"><h3>Relationship of the Horopter to Panum's Fusional Area</h3><p>The haplopic method demonstrates the existence of Panum's fusional area. This
|
|
concept allows for single binocular vision about the point of fixation, even
|
|
when corresponding retinal points are not being stimulated. An image on the
|
|
retina of one eye can be fused (and seen as single) with a similar image on the
|
|
retina of the other eye, although disparity in the retinal image exists. Panum's
|
|
fusional area is needed for stereopsis; if images do not fall in Panum's area,
|
|
then diplopia results—and so Panum's fusional area defines the zone
|
|
of stereovision.</p></div></div><div id="ch29space_perceptio.Aniseikonia"><h2 id="_ch29space_perceptio_Aniseikonia_">Aniseikonia</h2><p>Aniseikonia describes a subject's spatial perception when there is a difference in
|
|
retinal image size of the same object between the two eyes. Anisekonia can be
|
|
investigated by placing an aniseikonic lens placed in front of one eye (to magnify
|
|
the retinal image in one eye) while plotting the horopter using the AFPP method.
|
|
When this is performed, the apparent fronto-parallel plane becomes skewed about the
|
|
fixation point, with the horopter being nearer on the side of the eye having the
|
|
increased magnification (<a class="figpopup" href="/books/NBK11545/figure/ch29space_perceptio.F12/?report=objectonly" target="object" rid-figpopup="figch29spaceperceptioF12" rid-ob="figobch29spaceperceptioF12">Fig. 12</a>). Note that magnification
|
|
cannot be too large, otherwise, diplopia would result because the two retinal images
|
|
would fall outside Panum's fusional area. Aniseikonia identifies reshaping of visual
|
|
space within Panum's fusional area.</p><div class="iconblock whole_rhythm clearfix ten_col fig" id="figch29spaceperceptioF12" co-legend-rid="figlgndch29spaceperceptioF12"><a href="/books/NBK11545/figure/ch29space_perceptio.F12/?report=objectonly" target="object" title="Figure 12" class="img_link icnblk_img figpopup" rid-figpopup="figch29spaceperceptioF12" rid-ob="figobch29spaceperceptioF12"><img class="small-thumb" src="/books/NBK11545/bin/space_perceptionf12.gif" src-large="/books/NBK11545/bin/space_perceptionf12.jpg" alt="Figure 12. Plot of the horopter at 40 cm using the AFPP method with different magnification (2% and 4% magnification) lenses in front of one eye." /></a><div class="icnblk_cntnt" id="figlgndch29spaceperceptioF12"><h4 id="ch29space_perceptio.F12"><a href="/books/NBK11545/figure/ch29space_perceptio.F12/?report=objectonly" target="object" rid-ob="figobch29spaceperceptioF12">Figure 12</a></h4><p class="float-caption no_bottom_margin">Plot of the horopter at 40 cm using the AFPP method with different
|
|
magnification (2% and 4% magnification) lenses in front of one eye. From
|
|
Ogle (2). </p></div></div><p>The importance of these plots with the aniseikonic lens is to demonstrate stable
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corresponding retinal points. As long as the magnification difference between the
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two eyes is not too large, fusion will be maintained, although spatial distortions
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will occur. Once the magnification difference exceeds Panum's fusional space,
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diplopia will result. Aniseikonic symptoms are a common complaint of patients with
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unequal refractive errors or large astigmatic corrections. The magical 2-week rule
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applies, i.e., the time taken for sensory adaptation. If symptoms persist, reducing
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the magnification difference or reducing the correction are two clinical
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options.</p></div><div id="ch29space_perception.AFN1"><h2 id="_ch29space_perception_AFN1_">About the Authors</h2><p>
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<div class="graphic"><img src="/books/NBK11545/bin/psych1fu1.jpg" alt="Image psych1fu1.jpg" /></div>
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Michael Kalloniatis was born in Athens Greece in 1958. He
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received his optometry degree and Master's degree from the University of
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Melbourne. His PhD was awarded from the University of Houston, College of
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Optometry, for studies investigating colour vision processing in the monkey
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visual system. Post-doctoral training continued at the University of Texas
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in Houston with Dr Robert Marc. It was during this period that he developed
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a keen interest in retinal neurochemistry, but he also maintains an active
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research laboratory in visual psychophysics focussing on colour vision and
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visual adaptation. He was a faculty member of the Department of Optometry
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and Vision Sciences at the University of Melbourne until his recent move to
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New Zealand. Dr. Kalloniatis is now the Robert G. Leitl Professor of
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Optometry, Department of Optometry and Vision Science, University of
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Auckland. e-mail: <a href="mailto:dev@null" data-email="ua.ude.wsnu@sitainollak.m" class="oemail">ua.ude.wsnu@sitainollak.m</a></p><p>
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<div class="graphic"><img src="/books/NBK11545/bin/psych1fu2.jpg" alt="Image psych1fu2.jpg" /></div>
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Charles Luu was born in Can Tho, Vietnam in 1974. He was
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educated in Melbourne and received his optometry degree from the University
|
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of Melbourne in 1996 and proceeded to undertake a clinical residency within
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the Victorian College of Optometry. During this period, he completed
|
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post-graduate training and was awarded the post-graduate diploma in clinical
|
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optometry. His areas of expertise include low vision and contact lenses.
|
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During his tenure as a staff optometrist, he undertook teaching of optometry
|
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students as well as putting together the "Cyclopean Eye", in collaboration
|
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with Dr Michael Kalloniatis. The Cyclopean Eye is a Web based interactive
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unit used in undergraduate teaching of vision science to optometry students.
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He is currently in private optometric practice as well as a visiting
|
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clinician within the Department of Optometry and Vision Science, University
|
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of Melbourne.</p></div><div id="ch29space_perceptio.References"><h2 id="_ch29space_perceptio_References_">References</h2><dl class="temp-labeled-list"><dt>1.</dt><dd><div class="bk_ref" id="ch29space_perceptio.EXTYLES.1">Moses RA, Hart WM. <span class="ref-journal">Adler's physiology of the eye. Clinical application.</span> 8th
|
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ed. St. Louis (MO): The C. V. Mosby Company; 1987. </div></dd><dt>2.</dt><dd><div class="bk_ref" id="ch29space_perceptio.EXTYLES.2">Ogle KN. <span class="ref-journal">Researches in binocular vision.</span> London: Saunders; 1950. </div></dd></dl></div><div id="bk_toc_contnr"></div></div></div>
|
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<div class="post-content"><div><div class="half_rhythm"><a href="/books/about/copyright/">Copyright</a>: © 2025 Webvision .<p class="small">All copyright for chapters belongs to the individual authors who created them. However, for non-commercial, academic purposes, images and content from the chapters portion of Webvision may be used with a non-exclusive rights under a Attribution, <a href="https://creativecommons.org/licenses/by-nc/4.0/" ref="pagearea=meta&targetsite=external&targetcat=link&targettype=uri">Noncommercial 4.0 International (CC BY-NC) Creative Commons license</a>. Cite Webvision, http://webvision.med.utah.edu/ as the source. Commercial applications need to obtain license permission from the administrator of Webvision and are generally declined unless the copyright owner can/wants to donate or license material. Use online should be accompanied by a link back to the original source of the material. All imagery or content associated with blog posts belong to the authors of said posts, except where otherwise noted.</p></div><div class="small"><span class="label">Bookshelf ID: NBK11545</span><span class="label">PMID: <a href="https://pubmed.ncbi.nlm.nih.gov/21413400" title="PubMed record of this page" ref="pagearea=meta&targetsite=entrez&targetcat=link&targettype=pubmed">21413400</a></span></div><div style="margin-top:2em" class="bk_noprnt"><a class="bk_cntns" href="/books/n/webvision/">Contents</a><div class="pagination bk_noprnt"><a class="active page_link prev" href="/books/n/webvision/ch28kallcolor/" title="Previous page in this title">< Prev</a><a class="active page_link next" href="/books/n/webvision/ch30kalldepth/" title="Next page in this title">Next ></a></div></div></div></div>
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<div id="ncbi_share_book"><a href="#" class="ncbi_share" data-ncbi_share_config="popup:false,shorten:true" ref="id=NBK11545&db=books">Share</a></div>
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<div xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"></div><div class="portlet"><div class="portlet_head"><div class="portlet_title"><h3><span>Views</span></h3></div><a name="Shutter" sid="1" href="#" class="portlet_shutter" title="Show/hide content" remembercollapsed="true" pgsec_name="PDF_download" id="Shutter"></a></div><div class="portlet_content"><ul xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="simple-list"><li><a href="/books/NBK11545/?report=reader">PubReader</a></li><li><a href="/books/NBK11545/?report=printable">Print View</a></li><li><a data-jig="ncbidialog" href="#_ncbi_dlg_citbx_NBK11545" data-jigconfig="width:400,modal:true">Cite this Page</a><div id="_ncbi_dlg_citbx_NBK11545" style="display:none" title="Cite this Page"><div class="bk_tt">Kalloniatis M, Luu C. The Perception of Space. 2005 May 1 [Updated 2007 Jun 6]. In: Kolb H, Fernandez E, Jones B, et al., editors. Webvision: The Organization of the Retina and Visual System [Internet]. Salt Lake City (UT): University of Utah Health Sciences Center; 1995-. <span class="bk_cite_avail"></span></div></div></li><li><a href="/books/NBK11545/pdf/Bookshelf_NBK11545.pdf">PDF version of this page</a> (835K)</li><li><a href="/books/n/webvision/pdf/">PDF version of this title</a> (235M)</li></ul></div></div><div class="portlet"><div class="portlet_head"><div class="portlet_title"><h3><span>In this Page</span></h3></div><a name="Shutter" sid="1" href="#" class="portlet_shutter" title="Show/hide content" remembercollapsed="true" pgsec_name="page-toc" id="Shutter"></a></div><div class="portlet_content"><ul xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="simple-list"><li><a href="#ch29space_perceptio.Retinal_Disparity" ref="log$=inpage&link_id=inpage">Retinal Disparity</a></li><li><a href="#ch29space_perceptio.The_Horopter" ref="log$=inpage&link_id=inpage">The Horopter</a></li><li><a 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