Name: measuring visual attention lapses
Uploaded: 2023-04-30T06:46:22.000Z
Duration: 8 min 52 s
Channel: JoVE

K12 Standards

new-york-state-science-learning-standards

New York State Science Learning Standards

High School

Physical Science

HS. Waves and Electromagnetic Radiation

HS-PS4-5.

The Attentional Blink

1. 仪器设备
<ol>
	<li>该实验需要一台计算机以及实验实施软件（如 E-Prime），或编程环境（如 MATLAB 或 PsychoPy）。</li>
</ol>
2. 刺激与实验设计
<ol>
	<li>本实验依赖于一种称为快速序列视觉呈现（Rapid Serial Visual Presentation，简称 RSVP）的通用实验方法。
	<ol>
		<li>RSVP 的基本原理包括实验试次，其中一系列图像以快速连续的方式逐一呈现。每个图像通常在屏幕上停留不到 200 毫秒，随后即被下一个图像取代，从而难以对图像进行深入处理。</li>
	</ol>
	</li>
	<li>首先创建一个基本的 RSVP 程序。设置程序在屏幕中央呈现一串大的黑色小写字母（Helvetica 字体），每个字母仅持续 50 毫秒。字母在垂直方向上约占 2.5 英寸，水平方向约占 1.5 英寸。图 1 示意了一个 RSVP 序列。</li>
</ol>
<img alt="用于认知速度评估的反应时间测试示意图，包含视觉序列 S、V、J、F、D。" src="/files/ftp_upload/10211/10211fig1.jpg" data-altupdatedat="1761830439000" data-alt="图1"> 
图1：快速序列视觉呈现（RSVP）的基本原理。 一系列图像以极快速度连续呈现，在本例中为小写字母，每个字母仅显示50 ms，随后即被下一个字母取代。
<ol start="3">
	<li>现在，要将此程序设置为注意瞬脱程序，请按以下步骤操作：
	<ol>
		<li>进行长度为30张图像的试验-即将显示30个字符，每个字符持续50毫秒，使每次试验总共持续1.5秒。</li>
		<li>每次试验中的28个字符为上述小写字母，但其中有2个是数字。</li>
		<li>每次试验中，随机选择1到9之间的两个数字进行显示，但需确保同一次试验中的两个数字始终不同。</li>
		<li>在8的边界范围内随机选择第一个数字出现的位置th 项目呈现与20th 在每次试验中，将一个数字放置在8之间的某个位置。换句话说，每个项目呈现时th 和 20th 快速序列视觉呈现位置</li>
		<li>第二个数字出现在第一个数字之后，位置间隔从紧随其后到相隔六个位置不等。由于第二个数字的位置是相对于第一个数字定义的，因此这些位置被称为滞后位置。第二个数字的滞后位置范围为1至6。事实上，在整个实验过程中，滞后位置从1到6的每种情况均会出现相同次数。 图2 示意图解了滞后期位置的概念。</li>
		<li>将实验程序设置为共包含180个试验，每个滞后位置（1-6）各30个。</li>
		<li>每次试验结束时，屏幕应显示“第一？第二？”，如图所示 图2，以提示观察者报告他们在试验期间看到的数字。</li>
		<li>最后，设置程序以生成一个输出电子表格，报告所有相关数据。文件中的每一行对应单次试验的内容，应包含如下所示的以下信息： 图3试验编号、RSVP 序列中第一个数字的位置、第二个数字的滞后位置、第一个数字的真实身份、第二个数字的真实身份、参与者用于识别第一个数字的按键，以及识别第二个数字的相应按键。</li>
	</ol>
	</li>
</ol>
<img alt="Reaction time experiment diagram, showing sequence and lag between numbers and decision points." src="/files/ftp_upload/10211/10211fig2.jpg" data-altupdatedat="1761830439000" data-alt="Figure 2"> 
图2：注意瞬脱的实验方法。 预备屏幕显示后，接着呈现一个主要由字母组成的快速序列视觉呈现（RSVP）流，共包含30张图像。在这些字母中嵌入了两个数字，第一个数字出现在第8个位置至第13个位置之间的任意位置。th 以及 20th 流中的位置。第二个数字出现的位置称为“滞后”（lag），其定义相对于第一个数字的位置：紧随第一个数字之后的位置称为滞后1（lag 1），下一位为滞后2（lag 2），依此类推。该实验在滞后1至滞后6的每个条件下各进行30次试验。 
<img alt="注意瞬脱实验电子表格；数据录入字段包括试验编号、ID、反应数据。" src="/files/ftp_upload/10211/10211fig3.jpg" data-altupdatedat="1761830439000" data-alt="Figure 3"> 
图3：注意瞬脱实验数据输出表的结构。 每一行对应实验中的一个试验。需要记录的关键参数包括：序列中第一个数字出现的位置（取值范围为8至20）、到第二个数字的滞后位置（取值范围为1至6）、所呈现的两个数字的身份，以及参与者在每次试验结束时给出的反应。
3. 运行实验
<ol>
	<li>一个完整的实验最好测试 10–20 名参与者，但本实验的结果在大多数个体参与者的数据中应已明显可见。</li>
	<li>测试参与者时，让其坐在计算机显示器前，使其椅背距离屏幕约 60 cm。</li>
	<li>向其说明如下实验指导：
	<ol>
		<li>“本实验旨在研究人类注意力的速度。每次试验的流程基本相同。您将看到屏幕上显示单词‘Ready?’。屏幕将保持此状态，直到您按下空格键以启动一次试验。试验启动后，您将在屏幕中央看到一系列小写字母在 1.5 秒内快速呈现。两个数字将随机嵌入在这些字母之间，它们出现的位置是随机的，且不一定连续出现。您的任务是密切关注字母序列，并努力识别出其中出现的两个数字。每次试验结束后，系统会提示您输入您认为出现的两个数字，并按您记忆中出现的顺序依次输入，先输入第一个，再输入第二个。实验共包含 180 次试验，因此整个实验仅需 5–10 分钟。但非常重要的是，您需尽最大努力完成。如果在某次试验中无法确定某个数字，请随意猜测。有任何问题吗？”</li>
	</ol>
	</li>
	<li>回答完参与者的问题后，启动实验，并观察其完成几次试验，以防出现其他疑问。随后让参与者独立完成剩余实验。</li>
</ol>
4. 分析结果
<ol>
	<li>为了分析结果，首先要向当前已填充的数据电子表格中添加两列，一列命名为“正确性1”，另一列命名为“正确性2”，用于表示参与者在该次试验中是否正确识别了每个位置上的数字。将每次试验中实际出现的数字与参与者的回答进行比较，若回答正确，则在对应列中填入1，若回答错误，则填入0。图4展示了此时表格应有的样式。</li>
</ol>
<img alt="注意眨眼实验数据表；以电子表格格式显示的试验编号、响应及准确率指标。" src="/files/ftp_upload/10211/10211fig4.jpg" data-altupdatedat="1761830439000" data-alt="图 4"> 
图 4：注意眨眼实验填充后的数据输出结果。 “准确率1”和“准确率2”两列报告了参与者输入的响应是否与每次试验中呈现的数字实际身份相符。1 表示响应正确，0 表示响应错误。
<ol start="2">
	<li>现在计算参与者对第一个数字的总体反应正确率。通过计算电子表格中“正确率1”列数值的平均值来完成。该值应非常高，介于0.90至1之间。</li>
	<li>最后，分别计算第二个数字在六个滞后位置上的平均反应正确率。</li>
</ol>

与其他许多用于研究注意力的实验任务一样，注意瞬脱已成为研究脑损伤以及利用神经影像技术探究控制和协调注意力相关脑区的研究中的常用工具。
注意瞬脱范式还被用于研究可能自动捕获注意力的事物类型，以及焦虑和其他心理健康问题如何导致注意力分散。这些研究使用了与前述相同的范式，只是用真实世界的图像替代了字母。参与者的任务是检测任何处于异常位置的旋转图像，并在试验结束时报告该旋转图像是室内场景还是室外场景。图6A展示了这一基本范式的示例，而图6B则展示了如何利用该范式来探究某些刺激是否能自动捕获注意力。
<img alt="视觉加工的概念图示；情绪诱发刺激，目标识别实验。" src="/files/ftp_upload/10211/10211fig6.jpg" data-altupdatedat="1761830439000" data-alt="图 6"> 
图 6....

注意瞬脱

来源：Jonathan Flombaum 实验室——约翰斯·霍普金斯大学
要实现对某一特定刺激的识别，必须将视觉注意力指向该刺激。对于视觉系统的早期阶段而言，物体并非以“物体”的形式存在，而是表现为一系列视觉特征的集合——线条、拐角、纹理、颜色和光线的变化。注意力是后续加工过程中识别这些特征组合所代表的具体事物所必需的资源，因此注意力成为研究的核心课题。其中尤为重要的研究方向之一，是人们如何维持注意力，即个体在连续的时刻中持续保持注意力集中的程度。目前研究已知，维持注意力需要付出巨大的努力。当注意力需要迅速集中于快速移动或快速变化的目标时，一旦注意力解除，这种努力会导致注意力出现短暂的中断。这种注意力的短暂中断被称为“注意瞬脱”。它类似于大脑短暂地“眨眼”，暂时关闭注意力以获得片刻休息。在注意瞬脱期间出现的刺激将无法被感知。
1992年，一组研究人员设计了一种用于研究注意瞬脱的范式，该范式也因此得名1。这一范式揭示了维持集中注意力过程中存在的一些挑战。本视频演示了如何实施注意瞬脱范式，以研究持续的视觉注意力。

绘制第一个数字的平均反应正确率，以及第二个数字的反应正确率随滞后位置变化的图形。图5展示了示例。
<img alt="注意瞬脱图表显示准确率与滞后时间的关系，突出显示滞后1的保留效应和瞬脱效应。" src="/files/ftp_upload/10211/10211fig5.jpg" data-altupdatedat="1761830439000" data-alt="图5"> 
图5： 注意瞬脱实验的结果。 如图所示，参与者通常能够以非常高的准确率报告序列中的第一个数字，此处约为0.97。当第二个数字立即出现时，表现虽不如前者，但仍很高——这一现象称为滞后1保留效应。然而，在第二和第三滞后位置上，表现往往非常差，这被称为注意瞬脱，其含义是注意力被迅速调动以处理第一个数字后，会短暂地无法使用——类似于眨眼——在能够再次被调动以识别第二个数字之前...

来源：Jonathan Flombaum 实验室——约翰斯·霍普金斯大学  
为了实现对某一特定刺激的识别，视觉注意……

在快速变化的环境中处理信息具有较高要求，而视觉注意对于物体识别的发生至关重要。例如，要识别一组特征如何构成一个物体（如这个足球），需要视觉注意力，而维持这种注意力需要相当大的努力。在物品快速移动的动态情境中——例如比赛期间球场上的足球和球员——当注意力转移时，例如四分卫在寻找接球手时，所涉及的注意力投入会导致注意力出现短暂的松懈。这种现象被称为注意瞬脱，就像大脑短暂地“眨眼”了一下，暂时关闭注意力以进行休息，在此期间，诸如对手之类的刺激无法被感知。根据 Raymond、Shapiro 和 Arnell 于 1992 年开创的方法，本视频通过讲解设计刺激材料和实施范式的步骤，以及如何分析数据并解释在不同注意力投入水平下各试验中反应准确性的结果，演示了如何实现注意瞬脱现象。在本实验中，一系列图像（例如 Helvetica 字体的大写黑色小写字母和数字）将依次呈现，每次持续 50 毫秒，该实验程序简称为快速序列视觉呈现（Rapid Serial Visual Presentation，RSVP）。每次试验程序共显示30个字符，其中两张图片为1至9之间的不同数字。第一个数字随机出现在第8个到第20个快速序列视觉呈现（RSVP）位置之间，而第二个数字则随机插入在第一个数字之后，位置可紧随其后至其后第六位。这种间距称为滞后位置（lag position），范围为1到6。在整个实验过程中，共有180次试验，每个6个滞后位置各30次。每次试验结束后，要求参与者按快速序列视觉呈现（RSVP）中出现的顺序报告所看到的数字。因变量记录为在不同滞后位置上的正确响应数量。该范式的逻辑在于，第一个数字会吸引参与者的注意力，从而对第一个数字的命名具有很高的准确性。然而，根据滞后位置的不同，报告第二个数字时的表现预计会有所变化。如果它紧接在第一个之后出现，其表现应当仍然非常高——这一概念被称为滞后1节省效应。由于注意力眨眼现象，当第二个数字位于第二和第三滞后位置时，准确率受到的影响最为显著；而在较晚的滞后位置，即短时注意力眨眼窗口之后的位置，准确率受到的影响将较小。实验前，设置程序以生成一个输出电子表格，报告所有用于后续分析的相关数据，包括试验编号、RSVP 序列中第一个数字的位置及其滞后时间、第一个和第二个数字的真实身份，以及受试者的回答内容。首先，在实验室迎接参与者，并引导他们进入实验房间。让他们舒适地坐在计算机前，椅子与计算机之间的距离约为 60 cm。现在，说明任务说明：屏幕上将显示“Ready?”字样，直到按下空格键，随后一系列字母和数字会立即快速出现。指导受试者按照所看到数字的相同顺序，按下相应的按键来表明他们看到的数字。提醒他们，如果不确定看到的是什么数字，可以随意猜测。回答完所有问题后，离开房间，让他们完成所有滞后位置的 30 次试验，共计 180 次。完成后，感谢他们参与本次实验。开始数据分析时，打开包含实验数据输出的电子表格。添加两列，分别命名为“准确性1”和“准确性2”，用于指示参与者是否正确识别了每个位置上的数字。对于每次试验，在标有“准确度1”的列中，通过填写1表示受试者是否正确识别了第一个数字，填写0表示识别错误。对标有“准确度2”的列进行相同操作。接下来，绘制所有试验中第一个数字的平均准确率，以及第二个报告数字“Accuracy 2”按滞后位置的平均值。请注意，第一个数字的反应“准确率1”非常高，这表明即使数字出现时间极短、位置不可预测且夹在字母之间，集中注意力仍能支持对细节的加工和识别。正如所预测的，当第二个数字紧随第一个数字出现时，由于滞后1的豁免效应，准确率仍然保持较高水平。因此，由第一个数字引发的集中注意力仍处于持续参与状态，从而能够捕获第二个数字。然而，在滞后位置2和3时，平均准确率显著下降，反映了注意瞬脱现象。即在处理第一个数字后，注意力会暂时脱离，从而降低对后续刺激的加工与识别。然而，注意瞬脱持续时间较短，因为在滞后位置4、5和6的表现有所改善。 现在您已经熟悉了这一现象，接下来让我们更详细地探讨该范式如何用于研究视觉注意的基本局限性，包括哪些类型的刺激可能自动吸引注意力，以及焦虑和其他心理健康问题如何分散注意力。在一项类似的快速序列视觉呈现（RSVP）任务中，参与者被要求识别目标图像——即以异常角度旋转的图像。例如，将一个倒置的房间作为目标图像，参与者需报告该场景是室内还是室外。在一些实验中，研究人员在目标出现之前的视频流中添加了一只蜘蛛的图片。他们假设，由于蜘蛛会引发恐惧，可能会自动捕获受试者的注意力。在这种情况下，他们推断这将导致注意力眨眼现象，从而使受试者错过旋转后的目标。事实上，当目标出现之前呈现蜘蛛图像时，参与者的反应不准确，表明能引发恐惧的物体可自动捕获注意力并导致注意瞬脱。研究人员还使用相同的范式来探究患有严重恐惧症的人与仅对蜘蛛有普通厌恶感的人之间的差异。在此情况下，任务顺序被调换：预先展示旋转后的房间，使蜘蛛出现在滞后 2 的位置。因此，对于大多数参与者而言，蜘蛛的感知会因注意瞬脱而被阻断。有趣的是，患有严重蜘蛛恐惧症的个体并未表现出注意力瞬脱现象，因为他们报告看到了蜘蛛，这表明在某些情况下，当注意力本应脱离时，情绪性刺激会对注意力产生极强的吸引作用。您刚刚观看了 JoVE 关于注意瞬脱的简介。现在，您应该已经很好地掌握了如何设计和实施注意力参与任务，以及如何分析和评估结果。感谢观看！

Education

教育

JoVE Science Education

Psychology

心理学

Sensation and Perception

感觉与知觉

measuring visual attention lapses

Visual attention is needed to recognize a stimulus. Early in vision, objects are not seen as whole objects. They are processed as features such as lines, corners, texture changes, color, and light. Attention helps later processing combine those features into something the brain can identify.

This makes attention a major topic in vision research. A key question is how people sustain attention over time. Sustained attention means keeping focus from moment to moment. It takes effort, especially when attention must shift very quickly to something that is moving or changing rapidly.

That effort can cause a brief lapse after attention is disengaged. This lapse is called an attentional blink. During that short pause, stimuli that appear are not perceived. Researchers use the attentional blink paradigm, named for this effect, to study how well people maintain focused visual attention.

The paradigm was first devised in 1992. It shows some of the challenges of keeping attention steady under fast-changing conditions. The method in this video demonstrates how to implement the attentional blink paradigm for studying sustained visual attention.

Measuring Visual Attention Lapses

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perspectives on sensation and perception

Sensory Illusions in Perception

Sensation and perception explain how the brain turns sensory signals into what we see, hear, feel, and taste. Sensation is the process of transducing signals from sensory organs, such as the eyes. Perception is how the brain interprets those messages. This field has a long history that reaches back to the 19th century. During that time, scientists made major progress in understanding the properties of light and how they connect to the visual system. Those findings helped shape modern ideas...

motion-induced blindness

Visual Awareness Through Motion Illusion

Visual awareness and motion-induced blindness show how the brain shapes what people see. In visual perception and sensation, what appears in the world is not a direct copy of physical reality. People may miss real objects, see things that are not there, or see them in a distorted way. Scientists use the word awareness to mean what people actually perceive. To study awareness, vision researchers often rely on illusions and misperceptions. These cases help reveal how the brain builds experience...

the rubber hand illusion

Body Mapping and the Rubber Hand Illusion

The Rubber Hand Illusion shows how the brain builds a map of the body in space. This body map helps people reach for objects, walk without hitting obstacles, and sit down without missing a chair. It depends on proprioception, which is the brain's sense of where the limbs are based on control and feedback signals. The brain does not rely on proprioception alone. It also uses vision, touch, and even sound to represent body parts in space. The classic illusion, first described by Botvinick and...

the ames room

How the Ames Room Warps Depth

The Ames Room is a visual illusion that changes how people judge depth and size. It is built to show how the brain uses assumptions to recover three-dimensional space from a two-dimensional image on the retina. The retina is the light-sensitive tissue inside the human eye. Light from objects in the world reflects onto the retina and creates patterns of stimulation. Objects that are side-by-side in the world usually create side-by-side stimulations on the retina. Distance is harder to recover,...

inattentional blindness

Visual Attention and Missed Objects

Visual attention helps determine which parts of the visual world the brain processes and how well it processes them. Because attention is limited, people cannot take in everything at once, even when an object is right in front of them. Researchers began showing this effect in the 1960s. Ulrich Neisser demonstrated that people can miss visible objects when their attention is distracted. Later, in the 1980s and 1990s, Arien Mack and Irvin Rock built on that work and developed a simple way to...

spatial cueing

Measuring Visual Attention with Cues

Visual attention is the limited ability to focus on some information while ignoring other stimuli in the environment. It is studied in many senses, including vision, hearing, touch, taste, and smell. Researchers most often examine it in vision because it is easy to test with controlled displays. A common method is the spatial cueing paradigm. In this task, a cue appears to guide attention toward one location, and researchers measure what happens when attention is focused there instead of...

the attentional blink

Visual attention is needed to recognize a stimulus. Early in vision, objects are not seen as whole objects. They are processed as features such as lines, corners, texture changes, color, and light. Attention helps later processing combine those features into something the brain can identify. This makes attention a major topic in vision research. A key question is how people sustain attention over time. Sustained attention means keeping focus from moment to moment. It takes effort, especially...

crowding

Peripheral Vision and Letter Crowding

Peripheral vision and letter crowding are shown in this high school science video. The lesson connects how the eye samples light with why objects are harder to recognize at the edge of vision. Human vision depends on light-sensitive neurons in the back of the eye called the retina. These neurons are rods and cones, named for their shapes. They are not spread evenly across the retina. The center region, called the macula, has a dense pack of cones. Cones are especially concentrated in the...

the inverted-face effect

Face Recognition and Upside-Down Faces

Face recognition is a specialized part of human perception. It often feels effortless, but it actually depends on complex and intensive processing. The brain uses dedicated networks to detect faces and tell them apart.

the mcgurk effect

How Lip Reading Shapes Speech Perception

Speech perception depends on both hearing and vision. In many face-to-face conversations, the mouth gives strong visual clues about what a person is saying. Those clues can help the brain sort out speech sounds that are hard to hear clearly. This reliance on visual input is one reason spoken language is easier to understand when the speaker’s face is visible and close up. The mouth can sometimes provide better information than the sound alone. When the brain combines what it sees with what it...

just-noticeable differences

Measuring Size Changes with JND

Psychophysics studies how physical changes become neural signals and mental ideas about magnitude. A key idea in this field is the just-noticeable difference, or JND. A JND is the smallest change people can perceive. Size is a clear way to study JND. Small changes in a child’s height may go unnoticed from day to day. After a longer absence, such as a return from sleep-away camp or a visit after many weeks, those same small changes can seem obvious because they have added up. Researchers...

the staircase procedure for finding a perceptual threshold

the-staircase-procedure-for-finding-a-perceptual-threshold

Measuring Auditory Thresholds with Staircase Testing

Psychophysics studies how the physical strength of a stimulus relates to what people actually perceive. It focuses on perceptual thresholds, which are the smallest amounts of stimulation a person can sense. Examples include the brightness needed to see a light, the pressure needed to feel touch, and the softness of a sound that can still be heard. The staircase procedure is an efficient method for finding a perceptual threshold. Here, the stimulus is adjusted step by step based on a person’s...

object substitution masking

Visual Masking with Object Substitution

Visual masking describes cases where one image is presented, but an observer does not perceive it because a second image appears. In vision science, this kind of interference helps researchers study how the brain selects and stores visual information. Object substitution masking is a surprising form of visual masking. It became an important topic in vision research after it was discovered relatively recently, around 1997, by Enns and Di Lollo. The effect has been studied because it shows that...

sensation and perception

这本文集探讨了各种程序, 研究如何大脑处理我们复杂的感官世界, 解决问题的意识意识和视觉, 触觉, 和听觉感知。

Explore how the attentional blink reveals brief lapses in visual attention and how researchers use the paradigm to study sustained attention in fast-changing scenes.

Measuring Visual Attention Lapses | JoVE K12

Life Science

Structure and Function

HS-LS1-2.

Jonathan Flombaum

Overview

Stimulus and Experimental Design

Running the Experiment

Data Analysis and Representative Results

Applications

Summary

Travelling Waves

A wave is a disturbance that propagates from its source, repeating itself periodically, and is typically associated with simple harmonic motion. ...

Wave Parameters

The simplest mechanical waves are associated with simple harmonic motion and repeat themselves for several cycles. These simple harmonic waves can be ...

Equations of Wave Motion

Mathematically, the motion of a wave can be studied using a wavefunction. Consider a string oscillating up and down in simple harmonic motion, having a ...

Graphing the Wave Function

Consider the wave equation for a sinusoidal wave moving in the positive x-direction. The wave equation is a function of both position and time. From the ...

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Velocity and Acceleration of a Wave

A wave propagates through a medium with a constant speed, known as a wave velocity. It is different from the speed of the particles of the medium, which ...

Speed of a Transverse Wave

The speed of a wave depends on the characteristics of the medium. For example, in the case of a guitar, the strings vibrate to produce the sound. The ...

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problem-solving-tuning-of-a-guitar-string

Problem-Solving: Tuning of a Guitar String

In the case of stringed instruments like the guitar, the elastic property that determines the speed of the sound produced is its linear mass density or ...

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Kinetic and Potential Energy of a Wave

All forms of waves carry energy; this is directly visualized in nature. For instance, the waves of earthquakes are so intense that they can shake huge ...

Energy and Power of a Wave

The total energy associated with a wavelength is the sum of the potential energy and the kinetic energy. The average rate of energy transfer associated ...

Interference and Superposition of Waves

When two waves of the same nature occur in the same region simultaneously, they result in interference. Interference of waves implies that the net effect ...

Reflection of Waves

When a wave travels from one medium to another, it gets reflected at the boundary of the second medium. A common example of this is when a person yells at ...

Propagation of Waves

When a wave propagates from one medium to another, part of it may get reflected in the first medium, and part of it may get transmitted to the second ...

Standing Waves

Sometimes waves do not seem to move; rather, they just vibrate in place. Unmoving waves can be seen on the surface of a glass of milk kept in a ...

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Modes of Standing Waves - I

A close look at earthquakes provides evidence for the conditions appropriate for resonance, standing waves, and constructive and destructive interference. ...

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Modes of Standing Waves: II

The starting point for expressing the modes of standing waves is understanding the boundary conditions that the waves must follow. The boundary conditions ...

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Sound Waves

Sound waves can be thought of as fluctuations in the pressure of a medium through which they propagate. Since the pressure also makes the medium&#39;s ...

Sound as Pressure Waves

Sound waves, which are longitudinal waves, can be modeled as the displacement amplitude varying as a function of the spatial and temporal coordinates. As ...

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Perception of Sound Waves

The human ear is not equally sensitive to all frequencies in the audible range. It may perceive sound waves with the same pressure but different ...

Speed of Sound in Solids and Liquids

Most solids and liquids are incompressible&#8212;their densities remain constant throughout. In the presence of an external force, the molecules tend to ...

Speed of Sound in Gases

The speed of sound in a gaseous medium depends on various factors. Since gases constitute molecules that are free to move, they are highly compressible. ...

Shock Waves

While deriving the Doppler formula for the observed frequency of a sound wave, it is assumed that the speed of sound in the medium is greater than the ...

Echo

The human ear cannot distinguish between two sources of sound if they happen to reach within a specific time interval, typically 0.1 seconds apart. More ...

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Use mathematical representations to support a claim regarding relationships among the period, frequency, wavelength, and speed of waves traveling and transferring energy (amplitude, frequency) in various media.

HS-PS4-1.

Using GIS to Investigate Urban Forestry

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
Urban forests broadly include urban parks, street trees, landscaped ...

Evaluate questions about the advantages of using a digital transmission and storage of information.

HS-PS4-2.

concept-of-resonance-and-its-characteristics

Concept of Resonance and its Characteristics

If a driven oscillator needs to resonate at a specific frequency, then very light damping is required. An example of light damping includes playing piano ...

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Sound Waves: Resonance

Resonance is produced depending on the boundary conditions imposed on a wave. Resonance can be produced in a string under tension with symmetrical ...

Sound Waves: Interference

Sound waves can be modeled either as longitudinal waves, wherein the molecules of the medium oscillate around an equilibrium position, or as pressure ...

Interference: Path Lengths

Consider two sources of sound, that may or may not be in phase, emitting waves at a single frequency, and consider the frequencies to be the same.
Two ...

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The Wave Nature of Light

The nature of light has been a subject of inquiry since antiquity. In the seventeenth century, Isaac Newton performed experiments with lenses and prisms ...

The Electromagnetic Spectrum

The electromagnetic spectrum consists of all the types of electromagnetic radiation arranged according to their frequency and wavelength. Each of the ...

The Quantum-Mechanical Model of an Atom

Shortly after de Broglie published his ideas that the electron in a hydrogen atom could be better thought of as being a circular standing wave instead of ...

Quantum Numbers

It is said that the energy of an electron in an atom is quantized; that is, it can be equal only to certain specific values and can jump from one energy ...

Interference and Diffraction

Source: Yong P. Chen, PhD, Department of Physics &#38; Astronomy, College of Science, Purdue University, West Lafayette, IN
Interference and diffraction ...

Photoelectric Effect

Source: Yong P. Chen, PhD, Department of Physics &#38;&#38; Astronomy, College of Science, Purdue University, West Lafayette, IN
Photoelectric effect ...

Reflection and Refraction

Source: Derek Wilson,&#160;Asantha Cooray, PhD, Department of Physics &#38; Astronomy, School of Physical Sciences, University of California, Irvine, CA
...

Evaluate the claims, evidence, and reasoning behind the idea that electromagnetic radiation can be described either by a wave model or a particle model (quantum theory), and that for some situations one model is more useful than the other.

HS-PS4-3.

Electric Charge in a Magnetic Field

Source: Andrew Duffy, PhD, Department of Physics, Boston University, Boston, MA
This experiment duplicates J.J. Thomson's famous experiment at the end of ...

Electromagnetic Fields

Electric fields generated by static charges, often referred to as electrostatic fields, are characteristically different from electric fields created by ...

Electromagnetic Waves

James Clerk Maxwell formulated a single theory combining all the electric and magnetic effects scientists knew during that time, calling the phenomena his ...

Electromagnetic waves are categorized according to their wavelengths and frequencies, giving the electromagnetic spectrum. These waves are classified as ...

Plane Electromagnetic Waves I

The existence of combined electric and magnetic fields that propagate through space as electromagnetic (EM) waves is the most significant prediction of ...

Plane Electromagnetic Waves II

Consider a plane wavefront traveling in position x-direction with a constant speed. This wavefront can be utilized to obtain the relationship between ...

propagation-speed-of-electromagnetic-waves

Propagation Speed of Electromagnetic Waves

Electromagnetic waves are consistent with Ampere&#39;s law. Assuming there is no conduction current Ampere&#39;s law is given as:


Consider a plane ...

Electromagnetic Waves in Matter

Electromagnetic waves can travel in the vacuum as well as in matter. For example light, which is an electromagnetic wave, can travel through air, water, ...

Energy Carried By Electromagnetic Waves

Anyone who has used a microwave oven knows there is energy in electromagnetic waves. Sometimes, this energy is obvious, such as in the summer sun&#39;s ...

Intensity Of Electromagnetic Waves

The energy transport per unit area per unit time, or the Poynting vector, gives the energy flux of an electromagnetic wave at any specific time. For a ...

Momentum And Radiation Pressure

An object absorbing an electromagnetic wave would experience a force in the direction of propagation of the wave. This force occurs because ...

Cardiac Magnetic Resonance Imaging

Source: Frederick W. Damen and Craig J. Goergen, Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana
In this video, high ...

an-introduction-to-drosophila-melanogaster

An Introduction to Drosophila melanogaster

Drosophila melanogaster, also known as the fruit fly, is a powerful model organism widely used in biological research that has made significant ...

an-introduction-to-the-zebrafish-danio-rerio

An Introduction to the Zebrafish: Danio rerio

Zebrafish (Danio rerio) are small freshwater fish that are used as model organisms for biomedical research. The many strengths of these fish include their ...

Evaluate the validity and reliability of claims in published materials of the effects that different frequencies of electromagnetic radiation have when absorbed by matter.

HS-PS4-4.

Measuring Visual Attention Lapses

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