{"id":194,"date":"2019-06-04T13:15:22","date_gmt":"2019-06-04T17:15:22","guid":{"rendered":"https:\/\/pressbooks.library.ryerson.ca\/iwacc\/?post_type=chapter&#038;p=194"},"modified":"2019-07-30T11:22:12","modified_gmt":"2019-07-30T15:22:12","slug":"2-3-seizures-and-physical-reactions-level-aaa","status":"publish","type":"chapter","link":"https:\/\/pressbooks.library.torontomu.ca\/iwacc\/chapter\/2-3-seizures-and-physical-reactions-level-aaa\/","title":{"raw":"2.3 Seizures and Physical Reactions (Level AAA)","rendered":"2.3 Seizures and Physical Reactions (Level AAA)"},"content":{"raw":"<div style=\"margin: 1em 0;padding: 1em;border: 1px solid #ddd;border-left: 10px solid #ffcb05\">\r\n<h3><strong><a id=\"2.3.2\"><\/a>Success Criterion 2.3.2<\/strong> Three Flashes<\/h3>\r\nLevel AAA\r\n\r\n<a href=\"https:\/\/www.w3.org\/TR\/WCAG21\/#dfn-web-page-s\">Web pages<\/a> do not contain anything that <a href=\"https:\/\/www.w3.org\/TR\/WCAG21\/#dfn-flashes\">flashes<\/a> more than three times in any one second period.\r\n\r\n<\/div>\r\n<h4>Three Flashes Explained<\/h4>\r\nSome people are so sensitive that it is not possible to completely prevent them from having seizures. However, by eliminating all flashing between three and 50 flashes per second everywhere on the screen, the chances of a person having a seizure are reduced.\r\n\r\n<strong>SC 2.3.1<\/strong> Three Flashes or Below Threshold (Level A) allows flashing if it is dim enough or is confined to a small enough area. <strong>SC 2.3.2<\/strong>\u00a0(Level AAA) does not allow flashing at all between three and 50 flashes per second, regardless of brightness or size.\r\n\r\nEven a single flashing pixel violates this criterion. The intent is to guard against flashing areas that are larger than a single pixel; but, since an individual may require magnification or high contrast settings, the prohibition is against any flashing.\r\n<div style=\"margin: 1em 0;padding: 1em;border: 1px solid #ddd;border-left: 10px solid #b9f\">\r\n<h4><strong><a id=\"Try This: What Does Three Flashes Per Second Look Like?\u00a0\"><\/a>Try This: What Does Three Flashes Per Second Look Like?\u00a0<\/strong><\/h4>\r\n<div class=\"textbox\"><strong>Warning:<\/strong> If you are sensitive to flashing, don\u2019t do this activity.<\/div>\r\n<a href=\"http:\/\/moodlight.org\/#18204\">MoodLight<\/a>\r\n\r\nTo experience three flashes per second, open the MoodLight at the link above; choose two opposing colours that contrast well, like red and green; adjust the slider to \u201c3 times per second\u201d then press the \u201cTurn On\u201d button. Also, try flashing between 10 and 25 times per second \u2014 the range where the greatest sensitivity occurs \u2014 to experience what these frequencies look like.\r\n\r\n<strong>Note:<\/strong> The script that controls the flash rate does not work well at higher rates, so it isn\u2019t currently possible to experience the point at which the flashing becomes solid (at about 50 hz).\r\n\r\n<\/div>\r\n<div style=\"margin: 1em 0;padding: 1em;border: 1px solid #ddd;border-left: 10px solid #0000ff\">\r\n\r\n<strong>Suggested Reading: <\/strong>\r\n<ul>\r\n \t<li><a href=\"https:\/\/www.w3.org\/WAI\/WCAG21\/Understanding\/three-flashes.html\">Understanding Success Criterion 2.3.2 Three Flashes<\/a><\/li>\r\n \t<li><a href=\"https:\/\/www.w3.org\/WAI\/WCAG21\/quickref\/#three-flashes\">How to Meet Three Flashes<\/a><\/li>\r\n<\/ul>\r\n<\/div>\r\n<div style=\"margin: 1em 0;padding: 1em;border: 1px solid #ddd;border-left: 10px solid #ffcb05\">\r\n<h3><strong><a id=\"2.3.3\"><\/a>Success Criterion 2.3.3<\/strong> Animation from Interactions<\/h3>\r\n<span style=\"background-color: #00ff00;border: thin solid green;padding: 0.2em\"><strong>WCAG 2.1<\/strong><\/span>\r\n\r\nLevel AAA\r\n\r\n<a href=\"https:\/\/www.w3.org\/TR\/WCAG21\/#dfn-motion-animation\">Motion animation<\/a> triggered by interaction can be disabled, unless the animation is <a href=\"https:\/\/www.w3.org\/TR\/WCAG21\/#dfn-essential\">essential<\/a> to the functionality or the information being conveyed.\r\n\r\n<\/div>\r\n<h4>Animation from Interactions Explained<\/h4>\r\nWhile <strong>SC 2.2.2 <\/strong>Pause, Stop, Hide (Level A) addresses animation that is part of web content, <strong>SC 2.3.3 <\/strong>Animation from Interactions (Level AAA) addresses cases where movement occurs on the screen as a result of the user interacting with the content.\r\n\r\nPeople with <strong>vestibular disorders<\/strong>, which affect eye movement and balance control, may become dizzy (vertigo) or experience nausea or headaches when encountering content of significant size moving across their visual field. Rapidly paging through an ebook mimics the effect. A similar effect is motion sickness caused by looking out a side window of a moving car. Effects can be quite severe, potentially causing vomiting and requiring bed rest to reduce the symptoms.\r\n\r\nAs a result, any user-initiated animation should be avoided, or users should be provided with a way to disable such animations.\r\n\r\nThis success criteria does not apply to essential user-initiated animation. Scrolling, for example, is essential. In this case, users are in control and can adjust their scrolling speed to avoid any motion-related symptoms.\r\n\r\nOne form of motion in web content that is known to initiate vestibular dysfunction is parallax scrolling. This occurs when, while scrolling, the foreground and background scroll at different rates. If there is a significant difference in the scrolling rate, vestibular symptoms can be brought on.\r\n<div style=\"margin: 1em 0;padding: 1em;border: 1px solid #ddd;border-left: 10px solid #b9f\">\r\n<h4><strong><a id=\"Try This: Animation and Motion Sickness\"><\/a>Try This: Animation and Motion Sickness<\/strong><\/h4>\r\n<div class=\"textbox\"><strong>Warning<\/strong>: If you know you are sensitive to motion sickness be careful with this activity or avoid it altogether.<\/div>\r\nIf you have not experienced motion sickness before, this activity may not affect you. For many, though, animations like the following, when stared at for a period of time, can make them feel queasy. For those with a significant vestibular disorder, it may not take long before they start to feel sick. Scan through the following animations and choose one of the larger ones, with motion across the whole image. Stare at the image for a minute or two. Stop if or when you begin to feel off.\r\n\r\nDid you experience any reaction?\r\n\r\nPage with <a href=\"http:\/\/patakk.tumblr.com\/tagged\/gif\">motion GIFs<\/a> (click on an image to view it on its own, or choose one below):\r\n<ul>\r\n \t<li><a href=\"http:\/\/patakk.tumblr.com\/post\/22167608991\">Motion GIF 1<\/a><\/li>\r\n \t<li><a href=\"http:\/\/patakk.tumblr.com\/post\/33304597365\">Motion GIF 2<\/a><\/li>\r\n \t<li><a href=\"http:\/\/patakk.tumblr.com\/post\/15957100497\">Motion GIF 3<\/a><\/li>\r\n<\/ul>\r\n<\/div>\r\n<div style=\"margin: 1em 0;padding: 1em;border: 1px solid #ddd;border-left: 10px solid #0000ff\">\r\n\r\n<strong>Suggested Reading: <\/strong>\r\n<ul>\r\n \t<li><a href=\"https:\/\/www.w3.org\/WAI\/WCAG21\/Understanding\/animation-from-interactions.html\">Understanding Success Criterion 2.3.3 Animation from Interactions<\/a><\/li>\r\n \t<li><a href=\"https:\/\/www.w3.org\/WAI\/WCAG21\/quickref\/#animation-from-interactions\">How to Meet Animation from Interactions<\/a><\/li>\r\n \t<li><a href=\"https:\/\/webdesign.tutsplus.com\/tutorials\/a-guide-to-creating-accessible-animations--cms-32038\">A Guide to Creating Accessible Animation<\/a><\/li>\r\n<\/ul>\r\n<\/div>","rendered":"<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_80 counter-hierarchy ez-toc-counter ez-toc-grey ez-toc-container-direction\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">Contents<\/p>\n<label for=\"ez-toc-cssicon-toggle-item-69e8a9a0a55c7\" class=\"ez-toc-cssicon-toggle-label\"><span class=\"\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #999;color:#999\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewBox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #999;color:#999\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewBox=\"0 0 24 24\" version=\"1.2\" baseProfile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/span><\/label><input type=\"checkbox\"  id=\"ez-toc-cssicon-toggle-item-69e8a9a0a55c7\"  aria-label=\"Toggle\" \/><nav><ul class='ez-toc-list ez-toc-list-level-1 ' ><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/pressbooks.library.torontomu.ca\/iwacc\/chapter\/2-3-seizures-and-physical-reactions-level-aaa\/#Success_Criterion_232_Three_Flashes\" >Success Criterion 2.3.2 Three Flashes<\/a><ul class='ez-toc-list-level-4' ><li class='ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/pressbooks.library.torontomu.ca\/iwacc\/chapter\/2-3-seizures-and-physical-reactions-level-aaa\/#Three_Flashes_Explained\" >Three Flashes Explained<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/pressbooks.library.torontomu.ca\/iwacc\/chapter\/2-3-seizures-and-physical-reactions-level-aaa\/#Try_This_What_Does_Three_Flashes_Per_Second_Look_Like\" >Try This: What Does Three Flashes Per Second Look Like?\u00a0<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/pressbooks.library.torontomu.ca\/iwacc\/chapter\/2-3-seizures-and-physical-reactions-level-aaa\/#Success_Criterion_233_Animation_from_Interactions\" >Success Criterion 2.3.3 Animation from Interactions<\/a><ul class='ez-toc-list-level-4' ><li class='ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/pressbooks.library.torontomu.ca\/iwacc\/chapter\/2-3-seizures-and-physical-reactions-level-aaa\/#Animation_from_Interactions_Explained\" >Animation from Interactions Explained<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/pressbooks.library.torontomu.ca\/iwacc\/chapter\/2-3-seizures-and-physical-reactions-level-aaa\/#Try_This_Animation_and_Motion_Sickness\" >Try This: Animation and Motion Sickness<\/a><\/li><\/ul><\/li><\/ul><\/nav><\/div>\n<div style=\"margin: 1em 0;padding: 1em;border: 1px solid #ddd;border-left: 10px solid #ffcb05\">\n<h3><span class=\"ez-toc-section\" id=\"Success_Criterion_232_Three_Flashes\"><\/span><strong><a id=\"2.3.2\"><\/a>Success Criterion 2.3.2<\/strong> Three Flashes<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>Level AAA<\/p>\n<p><a href=\"https:\/\/www.w3.org\/TR\/WCAG21\/#dfn-web-page-s\">Web pages<\/a> do not contain anything that <a href=\"https:\/\/www.w3.org\/TR\/WCAG21\/#dfn-flashes\">flashes<\/a> more than three times in any one second period.<\/p>\n<\/div>\n<h4><span class=\"ez-toc-section\" id=\"Three_Flashes_Explained\"><\/span>Three Flashes Explained<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<p>Some people are so sensitive that it is not possible to completely prevent them from having seizures. However, by eliminating all flashing between three and 50 flashes per second everywhere on the screen, the chances of a person having a seizure are reduced.<\/p>\n<p><strong>SC 2.3.1<\/strong> Three Flashes or Below Threshold (Level A) allows flashing if it is dim enough or is confined to a small enough area. <strong>SC 2.3.2<\/strong>\u00a0(Level AAA) does not allow flashing at all between three and 50 flashes per second, regardless of brightness or size.<\/p>\n<p>Even a single flashing pixel violates this criterion. The intent is to guard against flashing areas that are larger than a single pixel; but, since an individual may require magnification or high contrast settings, the prohibition is against any flashing.<\/p>\n<div style=\"margin: 1em 0;padding: 1em;border: 1px solid #ddd;border-left: 10px solid #b9f\">\n<h4><strong><a><\/a>Try This: What Does Three Flashes Per Second Look Like?\u00a0<\/strong><\/h4>\n<div class=\"textbox\"><strong>Warning:<\/strong> If you are sensitive to flashing, don\u2019t do this activity.<\/div>\n<p><a href=\"http:\/\/moodlight.org\/#18204\">MoodLight<\/a><\/p>\n<p>To experience three flashes per second, open the MoodLight at the link above; choose two opposing colours that contrast well, like red and green; adjust the slider to \u201c3 times per second\u201d then press the \u201cTurn On\u201d button. Also, try flashing between 10 and 25 times per second \u2014 the range where the greatest sensitivity occurs \u2014 to experience what these frequencies look like.<\/p>\n<p><strong>Note:<\/strong> The script that controls the flash rate does not work well at higher rates, so it isn\u2019t currently possible to experience the point at which the flashing becomes solid (at about 50 hz).<\/p>\n<\/div>\n<div style=\"margin: 1em 0;padding: 1em;border: 1px solid #ddd;border-left: 10px solid #0000ff\">\n<p><strong>Suggested Reading: <\/strong><\/p>\n<ul>\n<li><a href=\"https:\/\/www.w3.org\/WAI\/WCAG21\/Understanding\/three-flashes.html\">Understanding Success Criterion 2.3.2 Three Flashes<\/a><\/li>\n<li><a href=\"https:\/\/www.w3.org\/WAI\/WCAG21\/quickref\/#three-flashes\">How to Meet Three Flashes<\/a><\/li>\n<\/ul>\n<\/div>\n<div style=\"margin: 1em 0;padding: 1em;border: 1px solid #ddd;border-left: 10px solid #ffcb05\">\n<h3><span class=\"ez-toc-section\" id=\"Success_Criterion_233_Animation_from_Interactions\"><\/span><strong><a id=\"2.3.3\"><\/a>Success Criterion 2.3.3<\/strong> Animation from Interactions<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p><span style=\"background-color: #00ff00;border: thin solid green;padding: 0.2em\"><strong>WCAG 2.1<\/strong><\/span><\/p>\n<p>Level AAA<\/p>\n<p><a href=\"https:\/\/www.w3.org\/TR\/WCAG21\/#dfn-motion-animation\">Motion animation<\/a> triggered by interaction can be disabled, unless the animation is <a href=\"https:\/\/www.w3.org\/TR\/WCAG21\/#dfn-essential\">essential<\/a> to the functionality or the information being conveyed.<\/p>\n<\/div>\n<h4><span class=\"ez-toc-section\" id=\"Animation_from_Interactions_Explained\"><\/span>Animation from Interactions Explained<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<p>While <strong>SC 2.2.2 <\/strong>Pause, Stop, Hide (Level A) addresses animation that is part of web content, <strong>SC 2.3.3 <\/strong>Animation from Interactions (Level AAA) addresses cases where movement occurs on the screen as a result of the user interacting with the content.<\/p>\n<p>People with <strong>vestibular disorders<\/strong>, which affect eye movement and balance control, may become dizzy (vertigo) or experience nausea or headaches when encountering content of significant size moving across their visual field. Rapidly paging through an ebook mimics the effect. A similar effect is motion sickness caused by looking out a side window of a moving car. Effects can be quite severe, potentially causing vomiting and requiring bed rest to reduce the symptoms.<\/p>\n<p>As a result, any user-initiated animation should be avoided, or users should be provided with a way to disable such animations.<\/p>\n<p>This success criteria does not apply to essential user-initiated animation. Scrolling, for example, is essential. In this case, users are in control and can adjust their scrolling speed to avoid any motion-related symptoms.<\/p>\n<p>One form of motion in web content that is known to initiate vestibular dysfunction is parallax scrolling. This occurs when, while scrolling, the foreground and background scroll at different rates. If there is a significant difference in the scrolling rate, vestibular symptoms can be brought on.<\/p>\n<div style=\"margin: 1em 0;padding: 1em;border: 1px solid #ddd;border-left: 10px solid #b9f\">\n<h4><strong><a><\/a>Try This: Animation and Motion Sickness<\/strong><\/h4>\n<div class=\"textbox\"><strong>Warning<\/strong>: If you know you are sensitive to motion sickness be careful with this activity or avoid it altogether.<\/div>\n<p>If you have not experienced motion sickness before, this activity may not affect you. For many, though, animations like the following, when stared at for a period of time, can make them feel queasy. For those with a significant vestibular disorder, it may not take long before they start to feel sick. Scan through the following animations and choose one of the larger ones, with motion across the whole image. Stare at the image for a minute or two. Stop if or when you begin to feel off.<\/p>\n<p>Did you experience any reaction?<\/p>\n<p>Page with <a href=\"http:\/\/patakk.tumblr.com\/tagged\/gif\">motion GIFs<\/a> (click on an image to view it on its own, or choose one below):<\/p>\n<ul>\n<li><a href=\"http:\/\/patakk.tumblr.com\/post\/22167608991\">Motion GIF 1<\/a><\/li>\n<li><a href=\"http:\/\/patakk.tumblr.com\/post\/33304597365\">Motion GIF 2<\/a><\/li>\n<li><a href=\"http:\/\/patakk.tumblr.com\/post\/15957100497\">Motion GIF 3<\/a><\/li>\n<\/ul>\n<\/div>\n<div style=\"margin: 1em 0;padding: 1em;border: 1px solid #ddd;border-left: 10px solid #0000ff\">\n<p><strong>Suggested Reading: <\/strong><\/p>\n<ul>\n<li><a href=\"https:\/\/www.w3.org\/WAI\/WCAG21\/Understanding\/animation-from-interactions.html\">Understanding Success Criterion 2.3.3 Animation from Interactions<\/a><\/li>\n<li><a href=\"https:\/\/www.w3.org\/WAI\/WCAG21\/quickref\/#animation-from-interactions\">How to Meet Animation from Interactions<\/a><\/li>\n<li><a href=\"https:\/\/webdesign.tutsplus.com\/tutorials\/a-guide-to-creating-accessible-animations--cms-32038\">A Guide to Creating Accessible Animation<\/a><\/li>\n<\/ul>\n<\/div>\n","protected":false},"author":100,"menu_order":7,"template":"","meta":{"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-194","chapter","type-chapter","status-publish","hentry"],"part":28,"_links":{"self":[{"href":"https:\/\/pressbooks.library.torontomu.ca\/iwacc\/wp-json\/pressbooks\/v2\/chapters\/194","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pressbooks.library.torontomu.ca\/iwacc\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/pressbooks.library.torontomu.ca\/iwacc\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/pressbooks.library.torontomu.ca\/iwacc\/wp-json\/wp\/v2\/users\/100"}],"version-history":[{"count":13,"href":"https:\/\/pressbooks.library.torontomu.ca\/iwacc\/wp-json\/pressbooks\/v2\/chapters\/194\/revisions"}],"predecessor-version":[{"id":1147,"href":"https:\/\/pressbooks.library.torontomu.ca\/iwacc\/wp-json\/pressbooks\/v2\/chapters\/194\/revisions\/1147"}],"part":[{"href":"https:\/\/pressbooks.library.torontomu.ca\/iwacc\/wp-json\/pressbooks\/v2\/parts\/28"}],"metadata":[{"href":"https:\/\/pressbooks.library.torontomu.ca\/iwacc\/wp-json\/pressbooks\/v2\/chapters\/194\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/pressbooks.library.torontomu.ca\/iwacc\/wp-json\/wp\/v2\/media?parent=194"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/pressbooks.library.torontomu.ca\/iwacc\/wp-json\/pressbooks\/v2\/chapter-type?post=194"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/pressbooks.library.torontomu.ca\/iwacc\/wp-json\/wp\/v2\/contributor?post=194"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/pressbooks.library.torontomu.ca\/iwacc\/wp-json\/wp\/v2\/license?post=194"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}