HUMAN CIRCULATORY SYSTEM COGNITIVE TASK ANALYSIS. Darnel Degand Teachers College, Columbia University

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1 HUMAN CIRCULATORY SYSTEM COGNITIVE TASK ANALYSIS HUMAN CIRCULATORY SYSTEM COGNITIVE TASK ANALYSIS Darnel Degand Teachers College, Columbia University MSTU 4133 Cognition and Computers Instructor Sui-Yee Chan October 26, 2006

2 HUMAN CIRCULATORY SYSTEM COGNITIVE TASK ANALYSIS 2 TABLE OF CONTENTS ABSTRACT 3 INTRODUCTION 3 COGNITIVE TASK ANALYSIS 4 Propositional Networks 6 Visuals and Imagery 9 Productions Systems 15 Mental Model 16 COGNITIVE DESIGN 17 Declarative Knowledge 17 Procedural Knowledge 18 Visual Knowledge 19 Mental Model 19 CONCLUSION REFERENCES

3 HUMAN CIRCULATORY SYSTEM COGNITIVE TASK ANALYSIS 3 ABSTRACT The human circulatory system is one of many organ systems at work in the human body. A cognitive task analysis for the human circulatory system is conducted in order to determine the knowledge representations that can be used to describe it. Using these knowledge representations as a guide, a cognitive design is performed to show how the human circulatory system can be taught. INTRODUCTION The human circulatory system is one of many organ systems at work in the human body. Wikipedia (2006) writes that The main components of the circulatory system are the heart, the blood, and the blood vessels (Closed circulatory system section, para. 1). On the National Health Museum website, Phillips (n.d.) states that the circulation of the blood serves to move blood to a site or sites where it can be oxygenated, and where wastes can be disposed. Circulation then serves to bring newly oxygenated blood to the tissues of the body (The Types of Circulatory Systems section, para. 1). Wikipedia (2006) describes the heart as pumping out blood to the rest of the body and taking it back in through the use of multiple blood vessels known as the arteries, capillaries, and veins (Closed circulatory system section, para. 3). First, oxygen rich blood flows out of the heart into the arteries. The blood then flows from the arteries into the capillaries. The capillaries allow the blood cells to deliver the nutrients and oxygen to the body s tissues through its walls. In exchange, the blood cells receive waste products and carbon dioxide sent from the body s tissues. At the end of this exchange, the deoxygenated blood, full of carbon dioxide and waste, exits the capillaries through the veins and returns back to the heart. (TIME-LIFE, 1992, p 62)

4 HUMAN CIRCULATORY SYSTEM COGNITIVE TASK ANALYSIS 4 Although many students are familiar with the heart and understand that blood pumps throughout their bodies, it is possible that they may not have a true understanding of how blood works to provide the body with the nutrients and oxygen it needs to function. Many students may also understand that blood pumps through their veins, however, they may not know that it also pumps through their arteries. In this paper a cognitive task analysis of the Human Circulatory System will be conducted in order to determine the main concepts that need to be taught to have a student successfully understand this topic. With these main concepts in mind, detailed information will be provided on the topic s Propositional Network, Production System, Visualizations, and Mental Models. The goal is to use the information that will be received from this cognitive task analysis as well as other cognitive and learning principles to discuss how the Human Circulatory System can be taught. COGNITIVE TASK ANALYSIS The Human Circulatory System is a very complex subject that needs to be visualized and comprehended on multiple levels. The student must be able to understand the system as a whole, but they also need to understand the smaller tasks at work within the main system. They need to understand the major steps involved in the circulation of blood throughout the system as well as how they interrelate. They also need to be able to visualize the system at work. The concept of nutrients and oxygen traveling within the blood must be transferred to them. Using the heart as the main central starting and ending point, the course the blood takes as it circulates once through the human circulatory system will be broken down into three phases. The first phase will describe the transportation of oxygenated blood from the heart to the capillaries. The second phase will describe the exchanges made between the blood and the

5 HUMAN CIRCULATORY SYSTEM COGNITIVE TASK ANALYSIS 5 body s tissues through the capillary walls. The third and final phase will describe the return of the deoxygenated blood from the capillaries back to the heart. For simplification purposes, the oxygenation of the blood and the removal of the waste from the blood before it begins a new cycle will be left out. The breakdown of the circulatory system into these three phases provides the student with a simpler global understanding of the system. This simplified global view gives them a good starting point from which they can then learn about the details of each phase. In the first phase, the students will have to be taught about the arteries and its significance to the heart. They will need to understand that the blood exiting the heart is full of the oxygen and nutrients the body needs to receive. They will also need to understand that the arteries main function is to transport this blood from the heart to the capillaries. The information from this first phase will be simplified and broken down into the following: (1) The heart pumps out blood full of oxygen and nutrients into the arteries, and (2) the arteries transport the blood into the capillaries. In the second phase, the students will need to visualize and comprehend the exchange taking place within the capillaries. They will need to understand that the blood releases all of its oxygen and nutrients into the body through the capillary walls and in exchange receives the waste and carbon dioxide released from the body. They will also be taught that the capillaries main function is to act as a medium between the blood and the rest of the body. The information from the second phase will be simplified and broken down into the following: (1) the oxygen and nutrients from the blood are transferred into the body through the capillary walls, and (2) the carbon dioxide and waste from the body are transferred into the blood through the capillary walls.

6 HUMAN CIRCULATORY SYSTEM COGNITIVE TASK ANALYSIS 6 In the third phase, the students will be taught about the veins and its role as the blood vessel that returns the deoxygenated blood back to the heart. They will learn that the blood entering back into the heart contains the carbon dioxide and waste picked up in the capillaries. The students will understand that the main function of the veins is to transport this blood back to the heart. The information in the third phase can be simplified and broken down into the following: (1) the veins transport the deoxygenated blood away from the capillaries, (2) the veins transport the blood into the heart. The following important information will also be included: (1) The Human Circulatory System includes the heart, blood vessels and blood and (2) Arteries, Veins, and Capillaries are blood vessels. Propositional Networks Propositional Representations are notations that represent the meaningful structure that remains after the perceptual details have been abstracted away (Anderson, 2005, p. 147). Propositional Representations are used to represent information defined as Declarative Knowledge. Chan (2006) informs us that the philosopher Gilbert Ryle defines Declarative Knowledge as Knowing That Something is the Case (as cited in Knowledge Representations section, para. 1) Using the sentences extracted from the cognitive task analyses performed on the Human Circulatory System above, several propositional representations will be created and combined to form propositional networks using John R. Anderson s version of a nodal propositional network. These propositional networks will include all of the declarative knowledge determined necessary for the student to have a good understanding of the Human Circulatory System.

7 HUMAN CIRCULATORY SYSTEM COGNITIVE TASK ANALYSIS 7 Figure 1 displays the Propositional Network for the following declarative knowledge information: (1) The Human Circulatory System includes the heart, blood vessels and blood, and (2) Arteries, Veins, and Capillaries are blood vessels. Figure 1: Propositional Network for Definitions Figure 2 displays the Propositional Network for the following declarative knowledge information from Phase One: (1) the heart pumps out blood full of oxygen and nutrients into the arteries, and (2) the arteries transport the blood into the capillaries. Figure 2: Propositional Network for Phase One

8 HUMAN CIRCULATORY SYSTEM COGNITIVE TASK ANALYSIS 8 Figure 3 displays the following declarative knowledge information from Phase Two: (1) the oxygen and nutrients from the blood are transferred into the body through the capillary walls, and (2) the carbon dioxide and waste from the body are transferred into the blood through the capillary walls. Figure 3: Propositional Network for Phase Two Figure 4 displays the following declarative knowledge information from Phase Three: (1) the veins transport the deoxygenated blood away from the capillaries, and (2) the veins transport the blood into the heart.

9 HUMAN CIRCULATORY SYSTEM COGNITIVE TASK ANALYSIS 9 Figure 4: Propositional Network for Phase Three Visuals and Imagery Image representations of the Human Circulatory System are needed in order to better visually describe how it works to the student. Chan & Black (2006) write that we need to know what something looks like and how it is laid out spatially that is, we need to know the mental images for it (para. 1). The following mental images will be used to visually describe the different parts of the human circulatory system as well as how blood circulates through the different parts. Figure 5 provides a visual representation of the human body. Figure 6 shows the human body with a visual representation of the human circulatory system inside. Figure 7 provides a close up of the heart along with the veins and arteries connected to it. Figure 8 displays the insides of an artery as well as the direction of the blood flowing from the heart through the artery. Figure 9 displays the insides of a vine as well as the direction of the blood flowing back to the heart. Figure 10 provides a mental image of the body and the capillaries. Figure 11 displays the oxygen and carbon dioxide exchange that occurs between the body and the blood.

10 HUMAN CIRCULATORY SYSTEM COGNITIVE TASK ANALYSIS 10 Figure 5: The Human Body

11 HUMAN CIRCULATORY SYSTEM COGNITIVE TASK ANALYSIS 11 Figure 6: The Human Circulatory System

12 HUMAN CIRCULATORY SYSTEM COGNITIVE TASK ANALYSIS 12 Figure 7: The Heart, Veins, and Artery

13 HUMAN CIRCULATORY SYSTEM COGNITIVE TASK ANALYSIS 13 Figure 8: Artery with blood flow away from heart Figure 9: Vein with blood flow back to heart

14 HUMAN CIRCULATORY SYSTEM COGNITIVE TASK ANALYSIS 14 Figure 10: The Capillaries Figure 11: Oxygen and Gas Exchange in Capillaries

15 HUMAN CIRCULATORY SYSTEM COGNITIVE TASK ANALYSIS 15 Production System Chan (2006) writes that Knowing How is called Procedural Knowledge because it captures what it means to know procedures for doing something. The Production System is the knowledge representation for Knowing How (Knowledge Representations section, para. 1). Using the sentences extracted from the cognitive task analyses performed on the human circulatory system above, a production system will be created to represent the procedural knowledge skills determined necessary for the student to fully understand the human circulatory system. The procedural knowledge skills required to understand the Human Circulatory System involve having the ability to identify the different types of blood vessels and identify what phase different events occur in. The production system provided below displays the procedures needed to accomplish each tasks. Production System: IF GOAL is to identify blood vessel THEN SUBGOAL is to identify if CO 2 and waste are replacing O 2 and nutrients IF YES THEN Identify Blood Vessel as a Capillary AND Identify Phase as Phase 2 IF NO THEN SUBGOAL is to identify content of blood IF blood contains oxygen and nutrients THEN Identify Blood Vessel as an Artery AND Identify Phase as Phase 1 IF blood contains oxygen and nutrients THEN Identify Blood Vessel as a Vein

16 HUMAN CIRCULATORY SYSTEM COGNITIVE TASK ANALYSIS 16 AND Identify Phase as Phase 3 IF GOAL is identify different phases of Human Circulatory System by events occurring THEN SUBGOAL is to identify if CO 2 and waste are replacing O 2 and nutrients IF YES THEN Identify phase as Phase 2 IF NO THEN SUBGOAL is to identify direction of flow blood relative to heart IF blood is flowing away from heart THEN Identify phase as Phase 1 IF blood is flowing back to heart THEN Identify phase as Phase 3 Mental Model Black (2006) defines a Mental model as a physical model that one can try things out on, but it exists in the mind of the reasoner. Having a mental model allows us to know why procedures work, and allows us to figure out new procedures when needed (p. 2). The mental model created below provides a good way for the students to conceptualize the circulation of the blood in their minds while also providing them with a simple way to think about the exchange taking place in the capillaries. The mental model for the human circulatory system involves having the student thinking about a village (where the villagers need food and water to survive) as representing the human body (where its tissues need oxygen and nutrients to survive). This mental model includes an ocean (the heart) that has water flowing out into a canal (the artery). This canal flows towards the village and breaks into smaller streams (capillaries) once it reaches the village. At the top of the streams, the villagers catch the fish and collect the fresh water. Following the water flow down to

17 HUMAN CIRCULATORY SYSTEM COGNITIVE TASK ANALYSIS 17 the bottom of the streams, we find the villagers dumping fish bones and dirty water into them. The streams continue to flow out into another canal (the vein). And this canal flows back out into the ocean (heart). Mental Model: Human Body Village. The villagers need food to eat and water and to drink. They also needs to discard of fish bones and dirty water Blood Flowing Water Heart Ocean Blood Vessels Canals and Streams Artery Canal flowing away from Ocean Capillaries Little streams that form from Artery Rivers and flow into Vein Rivers. At the beginning of the stream the villagers catch the fish for food and collect fresh water for drink. At the bottom of the stream fish bones are thrown back in and dirty water is also dumped in. Vein Canal flowing back into Ocean COGNITIVE DESIGN Using various instructional strategies, the students can be taught to learn the procedural, declarative, and visual knowledge this report has determined necessary in comprehending the human circulatory system. Strategies can also be used to help the students develop the mental model created in this report. Declarative Knowledge Anderson (2005) states It is easier to remember less meaningful material if it is converted into more meaningful material (p. 147). In teaching the declarative knowledge for this topic, the objective is to present the information in such a way that it helps the students

18 HUMAN CIRCULATORY SYSTEM COGNITIVE TASK ANALYSIS 18 retain the information. One way to help make the information more meaningful is to name each phase so that it describes the events that are occurring at that time. Remembering the names of each phase can also be made easier by naming each so that they all start with the same letter. Using the heart as the main central starting and ending point, the course the blood takes as it circulates once through the human circulatory system will taught to the students by braking it down into the following three phases: exit phase, exchange phase, and entrance phase. The exit phase will describe the transportation of oxygenated blood exiting out from the heart to the capillaries. The exchange phase will describe the exchanges made between the blood and the body s tissues through the capillary walls. The entrance phase will describe the transportation of the deoxygenated blood entering the heart. Another strategy that can be used to help the students differentiate between the blood vessels is the first letter in artery. Pointing out that Artery begins with an A and that the function of the artery is to take blood Away from the heart may also help. Procedural Knowledge Anderson (2005) defines Proceduralization as the process by which people switch from explicit use of declarative knowledge to direct application of procedural knowledge (p. 289). Giving the students several different quizzes where they are required to continuously identify the different blood vessels and the different phases involved in the circulation of blood throughout the human circulatory system will help them reach a point where they will not need to think as long and hard about what the differences are between the blood vessels and phases. Using tactical learning as the strategy, as students practice problems, they come to learn the sequences of actions required to solve a problem or parts of a problem (Anderson, p. 289).

19 HUMAN CIRCULATORY SYSTEM COGNITIVE TASK ANALYSIS 19 Visual Knowledge Researchers have found that memory for verbal material is greatly enhanced if one can develop visual images corresponding to the material (Anderson, 2000, p. 108). The students will come to a better understanding of the material if there are visuals that can be used to support the textual information describing the human circulatory system. Paivio has long championed the dual-code theory, which claims that there are separate representations for verbal and visual information (as cited in Anderson, 2000). When teaching this topic, the visuals in Figures 5-7 would be shown to provide them with an allocentric view of the human circulatory system. Figures 6-11 would be shown to the students to provide them with the egocentric view that allows them to visually and mentally navigate through the system. The students would also be asked to verbally describe the journey the blood takes as it circulates through the system. Having the students speak as they navigate the visual diagrams uses Baddeley s theory of working memory in which he hypothesizes that there are two systems, a visualspatial sketchpad, and a phonological loop, that basically correspond to the active components of Paivio s dual code theory ( as cited in Anderson, 2000) Mental Model Using the mental model of the village, a role playing video game would be developed for the students to play. In this game there will be four types of villagers: fishermen, water collectors, fish bone collectors, and dirty water removers. The villagers in the game are all nice people but have the tendency to wander off in the wrong direction. The objective of the game would be for the students to supervise the villagers and make sure that they do not go to the wrong parts of the stream to perform their duties (e.g. fisherman should not try and fish in the dirty water streams flowing back out into the river). The students would accumulate points

20 HUMAN CIRCULATORY SYSTEM COGNITIVE TASK ANALYSIS 20 depending on how many fish were caught and how many water buckets were successfully filled. They would also collect points for the fish bones and dirty water that were successfully discarded. As the game progresses, the village will grow to include more people and the amount of water and food supplies needed to feed them will also grow as well as the amount of fish bones and dirty water that needs to be discarded. At the end of the game the student will be asked a series of questions that are designed to examine how much of the similarities between the mental model and the human circulatory system were retained. Examples include: 1) What part of the human circulatory system does the ocean in the village game represent? 2) What happened when the villagers did not receive their food? What happens when our bodies do not receive oxygen and nutrients? 3) What do the fish bones and dirty water represent in the human circulatory system? CONCLUSION A cognitive task analysis of the human circulatory system was performed. Knowledge Representations were developed to describe the Declarative, Procedural, and Visual Knowledge necessary to successfully teach this topic to students. Using the information received from the cognitive task analysis, a Cognitive Design was developed describing how the information would be delivered to the students.

21 HUMAN CIRCULATORY SYSTEM COGNITIVE TASK ANALYSIS 21 REFERENCES Anderson, John R. (2005). Cognitive Psychology and its Implications (6 th ed.). New York, NY: Worth Publishers. Black, John. (2006). Mental Models and Mechanisms. Lecture given in MSTU 4133 Cognition and Computers, Teachers College, Columbia University, New York, NY. Chan & Black. (2006). Imagery and Visualization. Lecture given in MSTU 4133 Cognition and Computers, Teachers College, Columbia University, New York, NY. Chan, Sui-Yee. (2006). Propositions Networks and Schemas. Lecture given in MSTU 4133 Cognition and Computers, Teachers College, Columbia University, New York, NY. TIME-LIFE. (1992). Understanding Science & Nature: Human Body. Alexandria, VA: Robert H. Smith. National health Museum. (n.d.) The Heart and the Circulatory System. Retrieved October 24, 2006, from Wikipedia, the free encyclopedia. (2006, October 19) Circulatory system. Retrieved October 20, 2006, from

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