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JoVE Science Education

Uma videoteca dedicada a ensinar a prática e a teoria de experimentos científicos por meio de demonstrações visuais envolventes e fáceis de entender.

Education

Dichotic Listening

Source: Laboratory of Jonathan Flombaum&#8212;Johns Hopkins University

It is a well-known fact that the human ability to process incoming stimuli is limited. Nonetheless, the world is complicated, and there are always many things going on at once. Selective attention is the mechanism that allows humans and other animals to control which stimuli get processed and which become ignored. Think of a cocktail party: a person couldn&#8217;t possibly attend to all of the conversations taking place at once. However, everyone has the ability to selectively listen to one conversation, leading all the rest to become unattended to and nothing more than background noise. In order to study how people do this, researchers simulate a more controlled cocktail party environment by playing sounds to participants dichotically, i.e., by playing different sounds simultaneously to each ear. This is called a dichotic listening paradigm.
This experiment demonstrates standard procedures for investigating selective auditory attention with a paradigm called dichotic listening.

Dichotic Listening: Investigating Selective Auditory Attention

Escuta dicolatica

Source: Laboratory of Jonathan Flombaum&#8212;Johns Hopkins University

It is a well-known fact that the human ability to process incoming stimuli is ...

Measuring Reaction Time and Donders' Method of Subtraction

Source: Laboratory of Jonathan Flombaum&#8212;Johns Hopkins University

The ambition of experimental psychology is to characterize the mental events that support the human ability to solve problems, perceive the world, and turn thoughts into words and sentences. But people cannot see or feel those mental events; they cannot be weighed, combined in test tubes, or grown in a dish. Wanting to study mental life, nonetheless, Franciscus Donders, a Dutch ophthalmologist in the early 1800s, came up with a property that he could measure&#8212;even back then: he measured the time it took for human subjects to perform simple tasks, reasoning that he could treat those measurements as proxies for the time it takes to complete the unobservable mental operations involved. In fact, Donders went one step further, developing a basic experimental paradigm known as the Method of Subtraction. It simply asks a researcher to design two tasks that are identical in nearly every way, excepting a mental operation hypothesized to be involved in one of the tasks and omitted in the other. The researcher then measures the time it takes to complete each task, and by subtracting the outcomes, he extracts an estimate of the time it takes to execute the one mental operation of interest. In this way, the method allows a researcher to isolate a mental operation. The time it takes to complete a task has become known as reaction time or latency. Even today, reaction time is by a wide margin the most prevalent dependent variable in experimental psychology. &#160;

This video will demonstrate the measurement of reaction time using Donders&#8217; Method of Subtraction.

Measuring Reaction Time and Donders&#039; Method of Subtraction

Medindo o tempo de reação e o método de subtração de Donders

Source: Laboratory of Jonathan Flombaum&#8212;Johns Hopkins University

The ambition of experimental psychology is to characterize the mental events that ...

Visual Search for Features and Conjunctions

Source: Laboratory of Jonathan Flombaum&#8212;Johns Hopkins University

How do people find objects in cluttered visual scenes? Think, for example, of looking for keys on a messy desk, finding the ripest-looking fruit at the grocery store, locating your car when you can&#8217;t quite remember where you parked it, or finding an old friend at an airport exit gate. Clearly, an understanding of visual perception is going to play a role in any answers, and more specifically, an understanding of visual attention will be crucial.
Visual attention refers to the ability to focus in on just part of an image, mustering one&#8217;s processing resources selectively to determine whether the thing being looked for&#8212;the target, in the standard experimental jargon&#8212;is present. To study search and attention, experimental psychologists have developed a widely used paradigm known (unsurprisingly) as visual search.
Psychologists have also motivated a great deal of research by the intuition that any good theory of search is going to have, to explain why some things are easy to find and others are hard to find. So in the context of the visual search paradigm, perceptual psychologists have often focused on contrasting easy searches with more difficult ones. The most influential contrast is between what researchers call a feature search and a conjunction search.

Investigating Visual Attention by Feature and Conjunction Search

Busca visual por recursos e conjunções

Source: Laboratory of Jonathan Flombaum&#8212;Johns Hopkins University

How do people find objects in cluttered visual scenes? Think, for example, of ...

Perspectives on Cognitive Psychology

Source: Laboratory of Jonathan Flombaum&#8212;Johns Hopkins University

As an Assistant Professor of Psychology and Cognitive Science at Johns Hopkins University, I teach Introduction to Cognitive Psychology. This large class primarily consists of freshman and sophomores majoring in related fields, like Psychology, Neuroscience, or Cognitive Science. One of the challenges I face in the classroom is teaching students to appreciate how data are obtained in the process of performing experiments. Students have difficulty in appreciating the chronology of experiments as they unfold in time.
This JoVE collection in Cognitive Psychology makes the experimental timeline absolutely clear and encourages students to understand the trajectory and not just jump to conclusions. The videos also present experiments as paradigms&#8212;to illustrate how researchers can implement tasks in different ways&#8212;depending on the questions at hand. Most of these questions translate to the real world and the limits of our cognition. For example, the video Measuring Verbal Working Memory Span demonstrates our limited memory capacity, which explains the difficulty in remembering long shopping lists.
These JoVE videos in Cognitive Psychology provide a perfect place for instructors to start if they are interested in demonstrating tasks in class. Better yet, the videos can be used to get students involved&#8212;to execute the procedures and to even be the participants. Thus, the collection perfectly introduces lab components to a Psychology class.

Perspectivas sobre psicologia cognitiva

Source: Laboratory of Jonathan Flombaum&#8212;Johns Hopkins University

As an Assistant Professor of Psychology and Cognitive Science at Johns Hopkins ...

Binocular Rivalry

Source: Laboratory of Jonathan Flombaum&#8212;Johns Hopkins University

Why do people have two forward-facing eyes? By presenting the brain with two ever so slightly different images it becomes possible to comprehend visual problems that are far more difficult to process through a single eye. Chief among these is the problem of 3-D perception, seeing the world in three dimensions, despite retinal inputs in only two dimensions.
What happens if each eye receives two completely different images? That does not happen in nature, to be sure, but it can be contrived in the laboratory in a set-up called binocular rivalry.
Binocular rivalry is a common laboratory paradigm for investigating the ways that the brain integrates information from two eyes, and in recent years, the mechanisms responsible for producing conscious experience.

Binocular Rivalry: Studying Visual Perception and Neural Correlates of Consciousness

Rivalidade binóculo

Source: Laboratory of Jonathan Flombaum&#8212;Johns Hopkins University

Why do people have two forward-facing eyes? By presenting the brain with two ever ...

Multiple Object Tracking

Source: Laboratory of Jonathan Flombaum&#8212;Johns Hopkins University

In a staggeringly complex and engaging world, it is crucial to selectively process some stimuli at the expense of others. Experimental psychologists call this ability attention. Specifically, visual attention refers to the ability to selectively process aspects of a visual scene.
Many paradigms used to study visual attention involve brief, punctuated, and repeated trials. However, everyday situations often place sustained demands on attention, as opposed to requiring only brief focus. For example, compare driving through busy city streets, which demands sustained attention, with crossing a busy street, which demands just a few moments of caution. To investigate sustained visual attention, experimental psychologists typically rely on a paradigm called multiple object tracking.
This video demonstrates standard procedures for investigating sustained visual attention through multiple object tracking.

Multiple Object Tracking: Studying Sustained Visual Attention

Rastreamento múltiplo de objetos

Source: Laboratory of Jonathan Flombaum&#8212;Johns Hopkins University

In a staggeringly complex and engaging world, it is crucial to selectively process ...

Approximate Number Sense Test

Source: Laboratory of Jonathan Flombaum&#8212;Johns Hopkins University

A common carnival game is to ask people to guess the number of jellybeans packed into a jar. The chances that anyone will get the exact number right are low. But what about the chances that someone will guess 17 or 147,000? Probably even less than the chances of guessing the correct answer; 17 and 147,000 just seem irrational. Why? After all, if the beans cannot be taken out and counted one-at-a-time, how can someone tell that an estimate is too high or too low?
It turns out that in addition to verbal counting (something clearly learned), people appear to possess hardwired mental and neural mechanisms for estimating numbers. To put it colloquially, it is what might be called an ability to guesstimate, or &#8220;ballpark.&#8221; Experimental psychologists call it the &#8220;Approximate Number Sense,&#8221; and recent research with an experimental paradigm of the same name has begun to uncover the underlying computations and neural mechanisms that support the ability to guesstimate.
This video demonstrates standard procedures for investigating nonverbal numerical estimation with the Approximate Number Sense Test.

Teste de sentido de número aproximado

Source: Laboratory of Jonathan Flombaum&#8212;Johns Hopkins University

A common carnival game is to ask people to guess the number of jellybeans packed ...

Mental Rotation

Source: Laboratory of Jonathan Flombaum&#8212;Johns Hopkins University

Visual mental imagery refers to the ability to conjure images in one&#8217;s mind&#8217;s eye. This allows people to process visual material above and beyond the constraints of a current point-of-view; for example, a person could imagine, using their mind&#8217;s eye, how something might look in a different color, or what it would look like if it were made from a different material or rotated and seen from a different perspective. Mental imagery seems to support important human behaviors in many contexts. For example, people report visualizing routes and maps when planning a route or giving directions. They report visualizing movements, such as swinging a bat, to prepare for an actual action. They also report the mental rotation of objects in order to consider how an object might fit into a receptacle or clear a barrier.
This video demonstrates how to use the mental rotation procedure in order to investigate visual mental imagery.

Mental Rotation: Investigating Visual Mental Imagery

Rotação Mental

Source: Laboratory of Jonathan Flombaum&#8212;Johns Hopkins University

Visual mental imagery refers to the ability to conjure images in one&#8217;s ...

Prospect Theory

Source: Laboratory of Jonathan Flombaum&#8212;Johns Hopkins University

What&#8217;s the value of a dollar? Currencies store value to facilitate trade. Implied in any economic transaction is the value of a unit of currency. But what is the subjective value of a dollar? For a long time, economists assumed the answer to this question to be, specifically, that a dollar has a value determined by the market and that the subjective value of a dollar is always that, more or less.

Beginning in the early 1970s, experimental psychologists Daniel Kahneman and Amos Tversky upended this assumption, showing that the subjective value of currency depends on a number of factors, most notably, whether losses or gains are being discussed, and the overall size of a transaction. To pump intuition, consider the fact that, to most people, it would seem reasonable to drive an extra half-mile in order to save $2 on a gallon of gas. But very few people would do the same to save $2 on the cost of a new car. So $2 is sometimes, but not always worth an extra half-mile drive. Value is context-dependent.

The theory devised by Kahneman and Tversky to describe how people psychologically value currency (and goods and services, generally) is called Prospect Theory. In 2002, Kahneman was awarded the Nobel Prize in Economics for Prospect Theory, along with related research using the methods and theories of experimental psychology to understand economic decision-making (Tversky passed away in 1996.).

Many of the primary implications of Prospect Theory were obtained through survey experiments. The surveys consisted of choices between gambles; for example, subjects might be asked whether they would prefer to receive $5 or risk receiving nothing with a 50% chance of winning $10.

This video will demonstrate procedures for designing the type of survey questions used in research on Prospect Theory.

Studying Prospect Theory Through Survey

Teoria da Perspectiva

Source: Laboratory of Jonathan Flombaum&#8212;Johns Hopkins University

What&#8217;s the value of a dollar? Currencies store value to facilitate trade. ...

Measuring Verbal Working Memory Span

Source: Laboratory of Jonathan Flombaum&#8212;Johns Hopkins University

Why is it relatively hard to remember everything on a shopping list if it includes more than just a handful of items? Why is it possible to remember a phone number that one just heard, but not two or three phone numbers at once? Why is it difficult to remember names when several new people are introduced at the same time?
The answer has to do with the fact that over short-durations people rely on a specialized memory system called working memory. Unlike long-term memory, working memory has a very limited capacity. It is there so that information can be kept in mind, studied, manipulated, and then transferred to other memory and cognitive systems. But in order to serve in this active role, it needs to be selective, admitting only limited amounts of information at a time.
Experimental psychologists tend to think that people possess independent working memory systems for different kinds of information, with a major division between verbal and visual information. Each of these systems has an independent capacity limit.
To measure a person&#8217;s verbal working memory capacity limit&#8212;often called, his or her memory span&#8212;experimental psychologists often use a verbal list paradigm.
This video will demonstrate the measurement of verbal working memory span using a verbal list paradigm.

Medindo o período de memória de trabalho verbal

Source: Laboratory of Jonathan Flombaum&#8212;Johns Hopkins University

Why is it relatively hard to remember everything on a shopping list if it includes ...

The Precision of Visual Working Memory with Delayed Estimation

Source: Laboratory of Jonathan Flombaum&#8212;Johns Hopkins University

Human memory is limited. Throughout most of its history, experimental psychology has focused on investigating the discrete, quantitative limits of memory&#8212;how many individual pieces of information a person can remember. Recently, experimental psychologists have also become interested in more qualitative limits&#8212;how precisely is information stored?
The concept of memory precision can be both intuitive and elusive at once. It is intuitive, for example, to think a person can remember precisely how their mother sounds, making it possible to recognize one&#8217;s mother immediately over the phone or in a crowd. But how can one quantify the precision of such a memory? Exactly how similar is the memory to the voice itself?
To study the precision of memory and working memory, in particular, experimental psychologists have devised a paradigm known as delayed estimation. It has been used most often, thus far, to study the precision of visual memories, especially memory for color, and to understand how memory degrades the more one tries to remember at once. This video demonstrates standard procedures for investigating the precision of color working memory using delayed estimation, with a focus on how memory is affected as one tries to remember the colors of more objects simultaneously.

A precisão da memória visual de trabalho com estimativa atrasada

Source: Laboratory of Jonathan Flombaum&#8212;Johns Hopkins University

Human memory is limited. Throughout most of its history, experimental psychology ...

Verbal Priming

Source: Laboratory of Jonathan Flombaum&#8212;Johns Hopkins University

Human memory seems to work in two broad ways. Like modern computers, the human mind has explicit, or declarative, memory: ask a question, and a person gives the best answer they can. Input a query, and a computer program returns the contents of the relevant parts of its stored memory.
Humans also have a second kind of memory system, one not really typical of computers, one that experimental psychologists call implicit.
Implicit memory is a broad term that refers to the many ways past experiences influence present behavior. Pavlov&#8217;s famous dogs, for example, learned to associate the sound of a bell with mealtime. Eventually, they began salivating whenever they heard a bell, even if food was not delivered.
Humans also possess implicit memory. Implicit memories, for example, are the reason it can be difficult to fall asleep in a new place; people associate their bedroom environment and their nighttime routines with sleepiness.
Implicit memory is thought to guide human behavior in a wide array of circumstances. It is the kind of memory that guides manners and social behaviors, the kind of memory that puts relevant concepts and intuitions at a person&#8217;s fingertips. In many ways, implicit memory is what makes people prepared to process a new encounter in light of the past.
One way experimental psychologists investigate implicit memory is with a paradigm known as verbal priming. This video demonstrates a procedure for investigating the nature of implicit memory through verbal priming.

Verbal Priming: Investigating Implicit Memory

Source: Laboratory of Jonathan Flombaum&#8212;Johns Hopkins University

Human memory seems to work in two broad ways. Like modern computers, the human ...

Incidental Encoding

Source: Laboratory of Jonathan Flombaum&#8212;Johns Hopkins University

Long-term memory is a critical feature of human cognition, and it has been a prominent focus of research in experimental psychology. Many paradigms designed to tap long-term memory rely on asking participants to learn or study content, then test memory about that content. This is a good approach if one wants to understand how memory supports educational achievement, for example, where explicit study is part of the process. But, in day-to-day life, people often form new memories&#8212;many of which last for a long time&#8212;incidentally. People do not remember what they read in a magazine, the moment a partner was met, or the plot of a favorite story because they try to. Somehow, a good deal of experience just gets encoded into memory as life goes by. To study this side of long-term memory, experimental psychologists use something called an incidental-encoding paradigm.
The paradigm is especially useful for investigating the kinds of experiences that tend to produce strong long-term memories. Researchers think about experiences in terms of the kind of engagement they demand&#8212;personal, purely intellectual, deep, or shallow, for example. The incidental-encoding paradigm can be used to contrast long-term memory formation during different kinds of engagement by varying the cover task used to expose an individual to stimuli. A cover task is a task that a participant is asked to complete without knowing that memory for the stimuli in the task is tested later.
This video demonstrates standard procedures for using the incidental-encoding paradigm and two different cover tasks to investigate long-term memory when explicit study of a stimulus is not demanded.

Incidental Encoding: Investigating Implicit Long-term Memory

Codificação incidental

Source: Laboratory of Jonathan Flombaum&#8212;Johns Hopkins University

Long-term memory is a critical feature of human cognition, and it has been a ...

Visual Statistical Learning

Source: Laboratory of Jonathan Flombaum&#8212;Johns Hopkins University

The visual environment contains massive amounts of information involving the relations between objects in space and time; certain objects are more likely to appear in the vicinity of other objects. Learning these regularities can support a wide array of visual processing, including object recognition. Unsurprisingly, then, humans appear to learn these regularities automatically, quickly, and without conscious awareness. The name for this type of implicit learning is visual statistical learning. In the laboratory, it is studied with an incidental-encoding paradigm: participants observe a stream of nonsense objects and complete a cover-task, a task unrelated to the underlying statistical structure in the stream. But statistical structure is present, and subsequent to a short exposure period&#8212;as short as 10 min in some experiments&#8212;a familiarity test reveals the extent of learning by the participants.
This video will demonstrate standard methods for inducing and testing visual statistical learning.

Incidental Encoding: Testing Visual Statistical Learning

Aprendizagem Estatística Visual

Source: Laboratory of Jonathan Flombaum&#8212;Johns Hopkins University

The visual environment contains massive amounts of information involving the ...

Motor Learning in Mirror Drawing

Source: Laboratory of Jonathan Flombaum&#8212;Johns Hopkins University

Colloquially, the terms learning and memory encompass a broad range of behaviors and mental systems, everything from learning to tie a shoe to mastering calculus (and a lot in between). Experimental psychologists have divided up learning mechanisms into groups that seem to have different properties, and that seem to rely on different brain systems. A major division is between declarative and non-declarative memory, roughly, the sorts of things a person can express verbally&#8212;explicitly, like a birthdate, or what one ate for lunch&#8212;and things they cannot quite put into words&#8212;things they know implicitly, like how to get home despite not knowing the street names, or how to flip an omelet.

In the domain of non-declarative memory, a crucial kind of learning involves motor learning, sometimes also called procedural memory. Learning to drive a car is a good example. At first it is usually arduous and seems to involve explicit attempts to remember what to do next. Eventually it becomes second nature, though, something that a person just kind of knows how to do&#8212;and does better and better with time&#8212;but that can be hard to explain to someone else.
Mirror drawing is a common laboratory paradigm for investigating the acquisition of learned motor skills, the kind involved in driving, for example. This video demonstrates standard procedures for mirror drawing.

Mirror Drawing: Investigating the Acquisition of Motor Skills

Aprendizagem motora no desenho do espelho

Source: Laboratory of Jonathan Flombaum&#8212;Johns Hopkins University

Colloquially, the terms learning and memory encompass a broad range of behaviors ...

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