{"id":406,"date":"2023-03-02T20:16:36","date_gmt":"2023-03-02T20:16:36","guid":{"rendered":"https:\/\/content.one.lumenlearning.com\/introductiontopsychology\/chapter\/sensation-versus-perception\/"},"modified":"2026-02-04T17:54:35","modified_gmt":"2026-02-04T17:54:35","slug":"sensation-versus-perception","status":"publish","type":"chapter","link":"https:\/\/content.one.lumenlearning.com\/introductiontopsychology\/chapter\/sensation-versus-perception\/","title":{"raw":"Sensation and Perception: Learn it 1\u2014What is Sensation?","rendered":"Sensation and Perception: Learn it 1\u2014What is Sensation?"},"content":{"raw":"<section class=\"textbox learningGoals\">\r\n<ul>\r\n\t<li>Define sensation<\/li>\r\n\t<li>Define perception<\/li>\r\n<\/ul>\r\n<\/section>\r\n<h2><b>Sensation and Perception<\/b><\/h2>\r\n<p>You have probably known from a young age that we have five senses: vision, hearing (audition), smell (olfaction), taste (gustation), and touch (somatosensation). It turns out that this notion of five senses is oversimplified\u2014we also have sensory systems that provide information about balance (the vestibular sense), body position and movement (proprioception and kinesthesia), pain (nociception), and temperature (thermoception).<\/p>\r\n<h3><b>What Is Sensation?<\/b><\/h3>\r\n<section class=\"textbox keyTakeaway\">\r\n<h3>sensation<\/h3>\r\n<p><span class=\"s2\"><b>Sensation<\/b><\/span> occurs when <span class=\"s2\">specialized neurons<b> called sensory receptors<\/b><\/span> respond to specific kinds of stimuli in our environment.<\/p>\r\n<p>&nbsp;<\/p>\r\n<p class=\"p1\">When sensory information is detected by these receptors, a sensation has taken place.<br \/>\r\n<br \/>\r\n<\/p>\r\n<p class=\"p1\">This sensory input is then converted into <span class=\"s1\"><b>electrical signals (action potentials)<\/b><\/span> that travel to the <span class=\"s1\"><b>central nervous system<\/b><\/span> for processing\u2014a process called <span class=\"s1\"><b>transduction<\/b><\/span>. In other words, transduction transforms physical energy (like light waves or sound vibrations) into neural messages that your brain can interpret.<\/p>\r\n<\/section>\r\n<h3><b>Thresholds of Sensation<\/b><\/h3>\r\n<p class=\"p3\">Not all stimuli are strong enough for us to detect. Psychologists use several key concepts to explain our sensory limits.<\/p>\r\n<section class=\"textbox keyTakeaway\">\r\n<h3>absolute threshold<\/h3>\r\n<p><strong>Absolute threshold<\/strong> refers to the minimum amount of stimulus energy that must be present for the stimulus to be detected 50% of the time. Another way to think about this is by asking how dim can a light be or how soft can a sound be and still be detected half of the time. <br \/>\r\n<br \/>\r\nA stimulus reaches a physiological threshold when it is strong enough to excite sensory receptors and send nerve impulses to the brain: this is an absolute threshold.<\/p>\r\n<\/section>\r\n<p>The sensitivity of our sensory receptors can be quite amazing. It has been estimated that on a clear night, the most sensitive sensory cells in the back of the eye can detect a candle flame 30 miles away (Okawa &amp; Sampath, 2007). Under quiet conditions, the hair cells (the receptor cells of the inner ear) can detect the tick of a clock 20 feet away (Galanter, 1962).<\/p>\r\n<h3><b>Below Awareness: Subliminal Messages<\/b><\/h3>\r\n<p class=\"p3\"><span class=\"s2\">Sometimes, stimuli are presented <\/span>below the threshold of conscious awareness<span class=\"s2\">\u2014these are called <\/span><b>subliminal messages<\/b><span class=\"s2\">.<\/span><\/p>\r\n<section class=\"textbox keyTakeaway\">\r\n<h3>subliminal messages<\/h3>\r\n<p><strong>Subliminal messages<\/strong> register below the threshold\u2014they are not strong enough to excite sensory receptors and send nerve impulses to the brain. The message is received, but we are not consciously aware of it, and for whatever reason, it has not been selected for processing in working or short-term memory.<\/p>\r\n<\/section>\r\n<p class=\"p1\">Over the years, subliminal messages have been a source of fascination in advertising, music, and self-help media.<\/p>\r\n<p class=\"p1\">Research shows that people can process and even respond to some information <span class=\"s1\"><b>outside of awareness<\/b><\/span>, but these effects are typically <span class=\"s1\"><b>very small and short-lived<\/b><\/span>. Hidden messages do <span class=\"s1\"><b>not<\/b><\/span> control behavior (Kunst-Wilson &amp; Zajonc, 1980; Rensink, 2004; Nelson, 2008; Radel et al., 2009; Loersch, Durso, &amp; Petty, 2013).<\/p>\r\n<section class=\"textbox connectIt\">\r\n<h3>Dig Deeper: Nonconscious[footnote]Note that the term \"conscious\" generally refers to processing that occurs when we are awake. \"Nonconscious\" processing also occurs while awake, but below the level of awareness. This is similar to \"unconscious\" processing, which also occurs below the awareness threshold, but is more often used to describe those who are also not awake, as in, \"She was unconscious after the car crash.\" The terms nonconscious and unconscious are sometimes used interchangeably, however.[\/footnote] Perception<\/h3>\r\n<p class=\"p1\">Much of our mental processing happens <span class=\"s1\">nonconsciously<\/span>\u2014that is, while we are awake but unaware of it.<\/p>\r\n<p class=\"p1\">For example, we can form <span class=\"s1\">attitudes<\/span> toward things simply through <span class=\"s1\">repeated exposure<\/span>, even without realizing it. This phenomenon is known as the <span class=\"s1\"><b>mere exposure effect<\/b><\/span> (Zajonc, 1968).<\/p>\r\n<p class=\"p1\">People often develop positive feelings toward stimuli they\u2019ve encountered multiple times, even when those exposures were <span class=\"s1\">subliminal or extremely brief<\/span> (Kunst-Wilson &amp; Zajonc, 1980).<\/p>\r\n<\/section>\r\n<p>Absolute thresholds are generally measured under incredibly controlled conditions in situations that are optimal for sensitivity. Sometimes, we are more interested in how much difference in stimuli is required to detect a difference between them.<\/p>\r\n<section class=\"textbox keyTakeaway\">\r\n<h3><strong>just noticeable difference (jnd)<\/strong> or <strong>difference threshold<\/strong><\/h3>\r\n<p><strong>Just noticeable difference (jnd)<\/strong> or <strong>difference threshold <\/strong>is the difference in stimuli required to detect a difference between them. <br \/>\r\n<br \/>\r\nUnlike the absolute threshold, the difference threshold changes depending on the stimulus intensity. While there are estimations of humans' ability to detect differences in stimuli, the jnd can differ between individuals.<\/p>\r\n<\/section>\r\n<p class=\"p1\">For instance, a phone lighting up in a dark theater is obvious, but in a brightly lit gym, the same phone might go unnoticed.<\/p>\r\n<p class=\"p1\">The brightness doesn\u2019t change\u2014but our ability to detect it does.<\/p>\r\n<p>Ernst Weber proposed this theory of change in difference threshold in the 1830s, and it has become known as Weber's law.<\/p>\r\n<section class=\"textbox keyTakeaway\">\r\n<h3>Weber's law<\/h3>\r\n<p><strong>Weber\u2019s law <\/strong>states that the difference threshold is a constant fraction of the original stimulus; it is the idea that bigger stimuli require larger differences to be noticed. <br \/>\r\n<br \/>\r\nFor example, you might easily tell the difference between 1 and 2 pounds, but not between 10 and 11 pounds<\/p>\r\n<\/section>\r\n<section class=\"textbox tryIt\">[ohm2_question height=\"450\"]3983[\/ohm2_question]<\/section>","rendered":"<section class=\"textbox learningGoals\">\n<ul>\n<li>Define sensation<\/li>\n<li>Define perception<\/li>\n<\/ul>\n<\/section>\n<h2><b>Sensation and Perception<\/b><\/h2>\n<p>You have probably known from a young age that we have five senses: vision, hearing (audition), smell (olfaction), taste (gustation), and touch (somatosensation). It turns out that this notion of five senses is oversimplified\u2014we also have sensory systems that provide information about balance (the vestibular sense), body position and movement (proprioception and kinesthesia), pain (nociception), and temperature (thermoception).<\/p>\n<h3><b>What Is Sensation?<\/b><\/h3>\n<section class=\"textbox keyTakeaway\">\n<h3>sensation<\/h3>\n<p><span class=\"s2\"><b>Sensation<\/b><\/span> occurs when <span class=\"s2\">specialized neurons<b> called sensory receptors<\/b><\/span> respond to specific kinds of stimuli in our environment.<\/p>\n<p>&nbsp;<\/p>\n<p class=\"p1\">When sensory information is detected by these receptors, a sensation has taken place.<\/p>\n<p class=\"p1\">This sensory input is then converted into <span class=\"s1\"><b>electrical signals (action potentials)<\/b><\/span> that travel to the <span class=\"s1\"><b>central nervous system<\/b><\/span> for processing\u2014a process called <span class=\"s1\"><b>transduction<\/b><\/span>. In other words, transduction transforms physical energy (like light waves or sound vibrations) into neural messages that your brain can interpret.<\/p>\n<\/section>\n<h3><b>Thresholds of Sensation<\/b><\/h3>\n<p class=\"p3\">Not all stimuli are strong enough for us to detect. Psychologists use several key concepts to explain our sensory limits.<\/p>\n<section class=\"textbox keyTakeaway\">\n<h3>absolute threshold<\/h3>\n<p><strong>Absolute threshold<\/strong> refers to the minimum amount of stimulus energy that must be present for the stimulus to be detected 50% of the time. Another way to think about this is by asking how dim can a light be or how soft can a sound be and still be detected half of the time. <\/p>\n<p>A stimulus reaches a physiological threshold when it is strong enough to excite sensory receptors and send nerve impulses to the brain: this is an absolute threshold.<\/p>\n<\/section>\n<p>The sensitivity of our sensory receptors can be quite amazing. It has been estimated that on a clear night, the most sensitive sensory cells in the back of the eye can detect a candle flame 30 miles away (Okawa &amp; Sampath, 2007). Under quiet conditions, the hair cells (the receptor cells of the inner ear) can detect the tick of a clock 20 feet away (Galanter, 1962).<\/p>\n<h3><b>Below Awareness: Subliminal Messages<\/b><\/h3>\n<p class=\"p3\"><span class=\"s2\">Sometimes, stimuli are presented <\/span>below the threshold of conscious awareness<span class=\"s2\">\u2014these are called <\/span><b>subliminal messages<\/b><span class=\"s2\">.<\/span><\/p>\n<section class=\"textbox keyTakeaway\">\n<h3>subliminal messages<\/h3>\n<p><strong>Subliminal messages<\/strong> register below the threshold\u2014they are not strong enough to excite sensory receptors and send nerve impulses to the brain. The message is received, but we are not consciously aware of it, and for whatever reason, it has not been selected for processing in working or short-term memory.<\/p>\n<\/section>\n<p class=\"p1\">Over the years, subliminal messages have been a source of fascination in advertising, music, and self-help media.<\/p>\n<p class=\"p1\">Research shows that people can process and even respond to some information <span class=\"s1\"><b>outside of awareness<\/b><\/span>, but these effects are typically <span class=\"s1\"><b>very small and short-lived<\/b><\/span>. Hidden messages do <span class=\"s1\"><b>not<\/b><\/span> control behavior (Kunst-Wilson &amp; Zajonc, 1980; Rensink, 2004; Nelson, 2008; Radel et al., 2009; Loersch, Durso, &amp; Petty, 2013).<\/p>\n<section class=\"textbox connectIt\">\n<h3>Dig Deeper: Nonconscious<a class=\"footnote\" title=\"Note that the term &quot;conscious&quot; generally refers to processing that occurs when we are awake. &quot;Nonconscious&quot; processing also occurs while awake, but below the level of awareness. This is similar to &quot;unconscious&quot; processing, which also occurs below the awareness threshold, but is more often used to describe those who are also not awake, as in, &quot;She was unconscious after the car crash.&quot; The terms nonconscious and unconscious are sometimes used interchangeably, however.\" id=\"return-footnote-406-1\" href=\"#footnote-406-1\" aria-label=\"Footnote 1\"><sup class=\"footnote\">[1]<\/sup><\/a> Perception<\/h3>\n<p class=\"p1\">Much of our mental processing happens <span class=\"s1\">nonconsciously<\/span>\u2014that is, while we are awake but unaware of it.<\/p>\n<p class=\"p1\">For example, we can form <span class=\"s1\">attitudes<\/span> toward things simply through <span class=\"s1\">repeated exposure<\/span>, even without realizing it. This phenomenon is known as the <span class=\"s1\"><b>mere exposure effect<\/b><\/span> (Zajonc, 1968).<\/p>\n<p class=\"p1\">People often develop positive feelings toward stimuli they\u2019ve encountered multiple times, even when those exposures were <span class=\"s1\">subliminal or extremely brief<\/span> (Kunst-Wilson &amp; Zajonc, 1980).<\/p>\n<\/section>\n<p>Absolute thresholds are generally measured under incredibly controlled conditions in situations that are optimal for sensitivity. Sometimes, we are more interested in how much difference in stimuli is required to detect a difference between them.<\/p>\n<section class=\"textbox keyTakeaway\">\n<h3><strong>just noticeable difference (jnd)<\/strong> or <strong>difference threshold<\/strong><\/h3>\n<p><strong>Just noticeable difference (jnd)<\/strong> or <strong>difference threshold <\/strong>is the difference in stimuli required to detect a difference between them. <\/p>\n<p>Unlike the absolute threshold, the difference threshold changes depending on the stimulus intensity. While there are estimations of humans&#8217; ability to detect differences in stimuli, the jnd can differ between individuals.<\/p>\n<\/section>\n<p class=\"p1\">For instance, a phone lighting up in a dark theater is obvious, but in a brightly lit gym, the same phone might go unnoticed.<\/p>\n<p class=\"p1\">The brightness doesn\u2019t change\u2014but our ability to detect it does.<\/p>\n<p>Ernst Weber proposed this theory of change in difference threshold in the 1830s, and it has become known as Weber&#8217;s law.<\/p>\n<section class=\"textbox keyTakeaway\">\n<h3>Weber&#8217;s law<\/h3>\n<p><strong>Weber\u2019s law <\/strong>states that the difference threshold is a constant fraction of the original stimulus; it is the idea that bigger stimuli require larger differences to be noticed. <\/p>\n<p>For example, you might easily tell the difference between 1 and 2 pounds, but not between 10 and 11 pounds<\/p>\n<\/section>\n<section class=\"textbox tryIt\"><iframe loading=\"lazy\" id=\"ohm3983\" class=\"resizable\" src=\"https:\/\/ohm.one.lumenlearning.com\/multiembedq.php?id=3983&theme=lumen&iframe_resize_id=ohm3983&source=tnh&show_question_numbers\" width=\"100%\" height=\"450\"><\/iframe><\/section>\n<hr class=\"before-footnotes clear\" \/><div class=\"footnotes\"><ol><li id=\"footnote-406-1\">Note that the term \"conscious\" generally refers to processing that occurs when we are awake. \"Nonconscious\" processing also occurs while awake, but below the level of awareness. This is similar to \"unconscious\" processing, which also occurs below the awareness threshold, but is more often used to describe those who are also not awake, as in, \"She was unconscious after the car crash.\" The terms nonconscious and unconscious are sometimes used interchangeably, however. <a href=\"#return-footnote-406-1\" class=\"return-footnote\" aria-label=\"Return to footnote 1\">&crarr;<\/a><\/li><\/ol><\/div>","protected":false},"author":20,"menu_order":4,"template":"","meta":{"_candela_citation":"[{\"type\":\"cc\",\"description\":\"Sensation versus Perception\",\"author\":\"OpenStax College\",\"organization\":\"\",\"url\":\"https:\/\/openstax.org\/books\/psychology-2e\/pages\/5-1-sensation-versus-perception\",\"project\":\"\",\"license\":\"cc-by\",\"license_terms\":\"Download for free at https:\/\/openstax.org\/books\/psychology-2e\/pages\/1-introduction\"},{\"type\":\"original\",\"description\":\"Modification, adaptation, addition of Dig Deeper\",\"author\":\"\",\"organization\":\"Lumen Learning\",\"url\":\"\",\"project\":\"\",\"license\":\"cc-by\",\"license_terms\":\"\"},{\"type\":\"cc\",\"description\":\"Dig Deeper on the Unconscious and image\",\"author\":\"Ap Dijksterhuis Radboud\",\"organization\":\"University Nijmegen\",\"url\":\"http:\/\/nobaproject.com\/modules\/the-unconscious\",\"project\":\"The Noba Project\",\"license\":\"cc-by-nc-sa\",\"license_terms\":\"\"},{\"type\":\"cc\",\"description\":\"Sensation and Perception, last example on Weber\\'s Law\",\"author\":\"Adam John Privitera \",\"organization\":\"Chemeketa Community College\",\"url\":\"http:\/\/nobaproject.com\/modules\/sensation-and-perception\",\"project\":\"The Noba Project\",\"license\":\"cc-by-nc-sa\",\"license_terms\":\"\"},{\"type\":\"cc\",\"description\":\"Candle in the dark\",\"author\":\"pratanti\",\"organization\":\"\",\"url\":\"https:\/\/www.flickr.com\/photos\/pratanti\/3631956828\",\"project\":\"Flickr\",\"license\":\"cc-by\",\"license_terms\":\"\"},{\"type\":\"original\",\"description\":\"Details on nonconsciousness\",\"author\":\"Cynthia Golledge\",\"organization\":\"Portland Community College\",\"url\":\"\",\"project\":\"\",\"license\":\"cc-by\",\"license_terms\":\"\"}]","pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"part":402,"module-header":"learn_it","content_attributions":null,"internal_book_links":[],"video_content":null,"cc_video_embed_content":{"cc_scripts":"","media_targets":[]},"try_it_collection":null,"_links":{"self":[{"href":"https:\/\/content.one.lumenlearning.com\/introductiontopsychology\/wp-json\/pressbooks\/v2\/chapters\/406"}],"collection":[{"href":"https:\/\/content.one.lumenlearning.com\/introductiontopsychology\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/content.one.lumenlearning.com\/introductiontopsychology\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/content.one.lumenlearning.com\/introductiontopsychology\/wp-json\/wp\/v2\/users\/20"}],"version-history":[{"count":14,"href":"https:\/\/content.one.lumenlearning.com\/introductiontopsychology\/wp-json\/pressbooks\/v2\/chapters\/406\/revisions"}],"predecessor-version":[{"id":7617,"href":"https:\/\/content.one.lumenlearning.com\/introductiontopsychology\/wp-json\/pressbooks\/v2\/chapters\/406\/revisions\/7617"}],"part":[{"href":"https:\/\/content.one.lumenlearning.com\/introductiontopsychology\/wp-json\/pressbooks\/v2\/parts\/402"}],"metadata":[{"href":"https:\/\/content.one.lumenlearning.com\/introductiontopsychology\/wp-json\/pressbooks\/v2\/chapters\/406\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/content.one.lumenlearning.com\/introductiontopsychology\/wp-json\/wp\/v2\/media?parent=406"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/content.one.lumenlearning.com\/introductiontopsychology\/wp-json\/pressbooks\/v2\/chapter-type?post=406"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/content.one.lumenlearning.com\/introductiontopsychology\/wp-json\/wp\/v2\/contributor?post=406"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/content.one.lumenlearning.com\/introductiontopsychology\/wp-json\/wp\/v2\/license?post=406"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}