The present study explored the nature and frequency of physiology naïve beliefs by investigating novices' understanding of the respiratory system. Previous studies have shown considerable misconceptions related to physiology but focused mostly on specific physiological processes of normal respiration. Little is known about novices' broader understanding of breathing in a clinical context. Our study hypothesized that naïve beliefs could hamper participants' ability to understand the interrelatedness of respiratory structures and functions related to breathing during a clinical complication. The study entailed both quantitative and qualitative foci. A two-tier test was designed and administered to 211 first-year medical students. Participants were asked to choose the correct answer out of a set of four options and to substantiate their choices. Questions were purposefully left open to elicit a wide range of responses. Statistical analysis (SPSS) was done to evaluate the frequency of naïve beliefs. Thematic analysis was used to determine themes within the raw data. The majority of participants selected incorrect answers in the multiple-choice question part of the questionnaire. Results from the thematic analysis yielded a considerable range of naïve beliefs about gas exchange, foundational physics, airflow, anatomic structures, and breathing pathways. An awareness of the existence of such naive beliefs in respiratory physiology will allow educators to address them in their teaching and thereby prevent naïve beliefs transforming into misconceptions.
- medical students
- naive beliefs
- respiratory physiology
if first-year medical students, on arrival, have a relatively coherent yet novice understanding of biology and science, a medical curriculum should enable them to expand their knowledge. However, in one of the few studies pertaining to knowledge construction and the associated cognitive challenges in the early part of medical students' careers (2), it was found that first-year medical students arrive at their university with a substantial number of naïve preconceptions related to the cardiovascular system and that few of these disappeared after instruction. In a study (20) of senior medical students' ability to draw on foundational knowledge to explain a clinical scenario, a substantial lack of a stable long-term understanding of physiology was reported, suggesting that misconceptions can be one of the reasons why medical students rely on situational descriptions rather than a deeper level of understanding to explain physiological processes pertaining to organs and systems (8). “Naïve beliefs” refer to preinstructional conceptions held by learners, where these conceptions contradict current scientific views in the biomedical field, whereas misconceptions are erroneous ideas that persist after instruction (4, 5). Research over the past three decades (16) has shown that students arrive at science classes with naïve beliefs that are not necessarily supported by current scientific views. This would not constitute a problem if these ideas may simply be corrected by instruction. However, there is evidence that some of these naïve beliefs are resistant to change, because the framework in which they are embedded provided a sufficient basis for students to navigate their way successfully through previous similar learning activities (4, 5, 18, 19). Although some naïve beliefs can be remedied by simply adding knowledge, others might well be robust enough to become misconceptions in the students' later years (1, 4). If educators are aware of the scope of naïve beliefs present in novices' understanding of physiology, the construction of faulty mental models can be prevented in a timely manner. To this aim, we designed a study to explore the nature and frequency of novices' naïve beliefs pertaining to respiratory physiology so as to alert educators to potential sources of naïve beliefs that could impact on the application of foundational physiology to clinical scenarios in the later years.
Breathing is a complex process that requires an understanding of physics, chemistry, anatomy, and physiology. The following paragraphs describe the complex nature of breathing and form the basis of the two questions selected for this study.
During breathing, air moves into and out of the lungs in two stages, namely, inhalation and exhalation, respectively. The lungs cannot expand or contract on their own as they do not contain the necessary muscles. Inhalation and exhalation are therefore the result of movement performed by two sets of muscles, namely, the diaphragm and the intercostal muscles.
The diaphragm can be found at the bottom of the rib cage, separating the thorax from the abdomen. The movement of the diaphragm during breathing is often misunderstood. Before inhalation, the diaphragm is curved upward. During normal quiet breathing, also referred to as eupnea, as the person inhales, the diaphragm contracts and moves down. This movement causes an increase in the volume of the thorax. As the volume of the thorax increases, intrapleural pressure becomes more negative, expanding the alveoli. This causes alveolar pressure to decrease below atmospheric pressure, causing air to flow into the lungs. Relaxation of the diaphragm results in it returning to the shape of a dome, thereby decreasing the volume of the chest. As a result, intrapleural and alveolar pressures rise above atmospheric pressure, causing air to flow out of the lungs.
When the external intercostal muscles contract, the ribs move upward and outward, thus increasing the volume of the chest cavity, causing inhalation of air into the lungs. Exhalation occurs when the process is reversed; the muscles relax to their normal position, and the air is expelled. During normal breathing (eupnea), exhalation is a passive process, where inhalation involves the contraction of the intercostal muscles and the diaphragm.
Breathing is an automatic response and is controlled by the respiratory control center in the brain. The muscles we use for breathing can only contract if the spinal nerves are intact. The phrenic nerve that originates between the C3 and C5 vertebra in the neck, innervates the diaphragm, and thus controls its contraction. If this nerve is severed, inhalation is not possible. The control center in the brain, together with chemoreceptors, such as the carotid body for gas sensing, constantly monitors the levels of O2 and CO2 in the bloodstream and adjusts breathing rate and depth to maintain balance and homeostasis in the body. We therefore do not breathe because we “need O2” but rather to ensure homeostasis. An increased concentration of CO2 will result in the person breathing more deeply and frequently, whereas a low concentration of CO2 in the blood will decrease the frequency and depth of breathing.
Studies about novices' naïve beliefs and misconceptions about the respiratory system are scarce. A key study (11) identified four groups of prevailing misconceptions about the respiratory system, namely, misconceptions related to tidal volume and volume (1), a belief that if the Pco2 increases, the Po2 must decrease, a belief that blood in the pulmonary capillaries is a closed system that does not interact with alveolar gas, a faulty understanding of the relationship between O2 and CO2 in the body, a belief that the lungs are a closed system with a fixed volume, and an oversimplistic understanding of homeostasis, leading to a belief that all physiological process are held constant at all times. Studies (6, 12) have also shown that students use a teleological explanation for physiological processes in the body, for example, “we inhale because we need more O2.” In a study (3) about lecturers' perceptions of students' biomedical misconceptions, potential sources for misconceptions were identified, such as an inability to visualize a process or think in three dimensions, inability to move between the micro and macro levels, and faulty causal reasoning. With regard to physiology misconceptions, researchers have suggested remedial learning activities for the classroom (6, 10, 11, 13).
The above studies contributed significantly toward an understanding of misconceptions about respiratory physiology. They have, however, focused on specific physiological processes of respiration and excluded novices' broader understanding of breathing in a clinical context. Processes related to respiration take place on multiple levels, and students need to understand the interconnectedness of neural pathways, muscles, and the control system in the brain. Students also need to draw on foundational knowledge about breathing to apply causal reasoning and to predict an outcome. What makes our study novel is that we asked participants to draw on foundational anatomy, physiology, and physics to reason through a clinical complication. This process enabled us to investigate to what extent naïve beliefs play a role in first-year medical students' understanding of a complex system. Drawing on previous studies and the expertise of lecturers teaching in the first-year curriculum at the Faculty of Health Sciences, University of Cape Town, we hypothesized that the complexity of the respiratory system is a potential “breeding ground” for naïve beliefs that can interfere with a coherent understanding of the process. Our research question focused on two aspects of naïve beliefs in respiratory physiology, namely, what are some of these naïve beliefs and in the context of the study and how common are they. Our study further draws on conceptual change theory and the theory of complexity to explore why certain naïve beliefs are perpetuated or constructed during the learning process. Our results will be discussed in the context of these theories. In summary, drawing on key studies pertaining to respiratory physiology, we designed a study to explore students' reasoning processes when confronted with a complication to the entire respiratory system. Unlike previous studies, our study did not only explore naïve beliefs related to respiratory physiological processes but went further, to investigate whether students can integrate their understanding of all the components of breathing to explain what will happen when the system is compromised. To this end, we designed and administered a questionnaire to entering first-year medical students to correlate findings with previous studies as well as to describe and explain a broad scope of naïve beliefs about the respiratory system.
MATERIALS AND METHODS
All entering first-year medical students at the University of Cape Town on their arrival in 2013 were invited to participate in the study. Of these students, 211 of 218 students participated (n = 122 female students and 89 male students). As it is the case with many medical schools around the world, in South Africa, students who have met the necessary entrance criteria for a medical degree can register straight after school; therefore, the average age of participants was between 18 and 19 yr old. Selection into the medical school at the University of Cape Town is highly competitive, and only top achievers are offered places. From the ∼6,000 applicants from all over South Africa, only 250 students are currently selected. Selection is based on top grades, where science and mathematics are prerequisites.
We designed and administered a two-tier test that would assess students' content knowledge as well as their reasoning abilities in the specifically identified area of study (17). In the first tier, students were set multiple-choice questions about specific content, in this case, the process of breathing, whereas the second tier asked the student to provide an explanation for his/her choice in the first tier. Two-tier tests allow researchers to probe inconsistent thinking. For the purpose of this study, two problems pertaining to inhalation and exhalation were chosen to explore the nature and frequency of naïve beliefs in respiratory physiology. Our test was developed by a team of two anatomists and two physiologists, all teaching the first-year curriculum and therefore familiar with the content covered in the first year. The content of the test was informed by related studies (3, 6, 10, 11) as well as foundational knowledge covered in school biology. The first question was selected to gain insights into students' understanding of breathing, and the second question probed participants' application of breathing to a clinical scenario to explore application of basic knowledge. Participants were asked to choose the correct answer out of a set of four options and then had to substantiate their choices.
The first problem pertaining to respiratory physiology in the two-tier test was as follows:
Question 1. Air moves out of the lungs because:
A. The gas pressure in the lungs is less than the outside pressure
B. The volume of the lungs decreases with expiration (breathing out)
C. Contraction of the diaphragm decreases the volume of the pleural cavity
D. CO2 is higher inside the lungs compared with O2
The correct reasoning, answer B, is that air moves out of the lungs because of a decrease of their volume. During normal breathing, as the diaphragm and the external intercostal muscles relax, the volume of the thoracic cavity decreases and pressure increases.
The second problem was as follows:
Question 2. If a person is paralyzed from the neck down, he/she will be able to:
A. Breathe in
B. breathe out
C. Breathe in and out
D. Breathe neither in or out
The correct reasoning, answer B, is that, strictly speaking, the person would only be able to exhale once, since exhalation is an inactive process. The position of the injury indicates that the person will not be able to use muscles to breathe in again and continue breathing without assistance.
The two-tier test was piloted on 50 second-year physiology students to establish if the instructions were clear and whether the problems would trigger naïve beliefs. The instrument was refined to ensure that instructions and wording were clear. Both questions were purposefully left open ended to allow for a broad range of answers from participants to probe naïve beliefs and inconsistent thinking between the two tiers. In qualitative research, such questions are exploratory in nature to allow for rich data by allowing participants freedom to respond. Ethical clearance was obtained for the study from the University of Cape Town Human Ethics Research Committee (HREC Ref. 563/2012). E. Badenhorst conducted an information session on the study with all first-year medical students during the customary orientation period and invited them to participate. As the test was computer based, a digital literacy lecturer together with E. Badenhorst attended the testing session to ensure that all students were familiar with the use of computers.
For the quantitative analysis, the frequency of incorrect answers for each problem was computed. Analytic induction was used to uncover categories within the set of raw data. This was done to allow for patterns of analysis to emerge from the data and to prevent our imposition of such patterns before data collection and analysis (14). To ensure validity, two anatomists and two physiologists (J. Friedling, G. Gunston, K. Bugarith, and R. Kelly-Laubscher) independently assigned categories to participants' rationale for their choices by clustering ideas that pertained to the same notion. This process was used to determine if units with relevant meaning naturally clustered together and to ensure triangulation (6). After this, a consensus meeting was held with two physiologists (K. Bugarith and R. Kelly-Laubscher) to explore whether results from the initial analysis could be collapsed to yield broader, summative themes (8). Eight themes of naïve beliefs (four themes for question 1 and four themes for question 2) were chosen for a second round of analysis to categorize the raw data. Two physiologists and an anatomist (A. Abrahams, K. Bugarith, and G. Gunston) independently summarized the incorrect responses for both problems into the eight themes. Responses that were not clear or were ambiguous were excluded. Only results for which there was consensus among all three raters per theme were included in the results.
For the analysis of both questions, we first eliminated all responses where participants did not complete the full test or gave ambiguous responses, such as “I just guessed the answer.” We further eliminated responses where raters disagreed, leaving us with a total of 179 responses for both questions. We then subtracted the correct responses, which left us with 138 responses for the air flow problem (question 1) and 175 for the paralysis question (question 2). These responses were analyzed for themes.
In both problems, the majority of the participants chose incorrect options. Please refer to Table 1 for the results from the first tier of the test and Table 2 for the results from the second tier. In the air movement problem (question 1), the majority of participants chose answer D, “CO2 is higher in the lungs than O2.” The second most frequent choice was answer C, “the diaphragm contracts to decrease the volume of the pleural cavity”. In the paralysis problem (question 2), the majority of participants chose answer C, “the person would be able to breathe in and out,” with answer D, “the person can breathe neither in nor out,” as second highest.
With regard to the second tier of the test, 138 incorrect responses for the first problem and 175 for the second problem were analyzed for themes. The first theme of naïve beliefs regarding the air movement problem indicated that participants believed there is a direct relation between high levels of CO2 and expiration, causing a need to inhale O2. The highest frequency (n = 69) of responses fell into this category. The second theme involved the role of the diaphragm in regulating the volume of the thoracic cavity, with a frequency of 50 responses falling into this category. In this theme, participants typically confused the contraction and relaxation of the diaphragm and the subsequent movement of air out of the body. The third theme focused on volume and pressure inside and outside the lungs. The responses indicated that participants struggled with applying Boyle's law correctly. A total of 15 responses fell into this category. Finally, a small frequency of responses (n = 4) showed participants confusing expulsion of air with gas exchange at alveolar level. Please refer to Tables 3 and 4 for examples from the raw data.
With regard to the paralysis problem, the most frequent theme related to the role of muscles in breathing. The highest number (n = 69) of responses indicated that participants were confused about muscle movement during inhalation and exhalation and henced interpreted exhalation as an active process. Second, the responses indicated naïve beliefs about nerve pathways in the body. Participants believed that muscles and nerves work independently (n = 65). The third theme indicated that participants did not understand the anatomy and physiology of the respiratory pathway, believing that the nose works independently from the rest of this pathway (n = 22). Finally, some responses indicated that participants cling to everyday explanations that are unscientific (n = 19).
The present study set out to explore the nature and extent of novices' naïve beliefs about the respiratory system, specifically with regard to predicting respiratory processes related to inhalation and exhalation. The researchers hypothesized that such naïve beliefs could hamper students' ability to perform coherent causal reasoning. To test this hypothesis, we administered a two-tier test to novices on their arrival at medical school to investigate the scope of naïve beliefs related to the respiratory process, with a specific focus on exploring students' reasoning processes when applying foundational knowledge to explain a clinical complication. Although we anticipated that the complex nature of the breathing process would uncover some naïve beliefs, the results revealed more naive beliefs than expected. For both problems, the majority of participants selected incorrect answers in the first tier (multiple choice) of the questionnaire. This, in itself, is not necessarily proof that naïve beliefs exist. Results from the thematic analysis (second tier), however, revealed a considerable range of naïve beliefs about gas exchange, foundational physics concerning concentration and airflow, the role of the diaphragm, the physiological pathway related to breathing, and the difference between active and inactive breathing.
In total, we found eight major categories of naïve beliefs about breathing. First, participants disregarded the role of nerves in the stimulation of muscles during inhalation. Participants seemed to believe that muscles work independently from the spinal nerves (which are controlled by the brain), for example, “Even though you are unable to move any part of your body from the neck downwards, breathing is an automatic process that isn't affected by being paralyzed” and “the person can still breathe because the diaphragm will move up and down to move air in and out.” This could be an indication that students are not applying causal reasoning, thereby corroborating findings by other studies (3, 4, 11). They therefore do not discern cause and effect (that the nerves cause the muscles to contract, hence increasing the volume of the thoracic cavity, causing a difference in pressure, which results in air flow). Second, participants held naïve beliefs pertaining to the role of the contraction and relaxation of the diaphragm in relation to the volume of the thoracic cavity and the subsequent impact on air flow, for example, “when u breathe out the diaphragm is squeezing the lungs to release air” and “as the diaphragm contracts, it forces air out.” This may be an indication that students struggle to visualize the process or that they have constructed faulty mental models, confusing the role of contraction in relation to the volume of the thoracic cavity. This finding confirmed results from a study (3) about lecturers' perceptions of medical students' biomedical misconceptions, indicating that students have difficulties to form a mental representation of a complex process. Third, participants hold an overtly simplistic understanding of the reason why air moves in and out of the body, thus disregarding the complexity of this process, for example, “They can still use their mouth and nose to force breathing” and “homeostasis must be restored, so you need to get rid of air.” This indicates that students do not fully grasp the intricacies of the process. Sweller's notion of complexity (15) explains that naïve beliefs arise because students have an overly simplistic understanding of complex processes. Examples such as “because paralyzed people breath and their hearts beat which means that it is possible to breathe in and out,” “because the paralysis of the neck has nothing to do with the respiratory system,” and “the brain isn't damaged it is just the spine” demonstrate that students do not understand the complexity of respiration and paralysis. Thus, they treat respiration as a simplistic concept that is made up of the nose, the lungs, and air (“the nose can still work to breathe”), ignoring the complexity of gas exchange, air flow, pressure, and the interrelated respiratory control systems. In this case, the anatomic structures and physiological processes pertaining to respiration may appear to be simple, but, in fact, demand a complex range of cognitive actions for a student to construct a coherent understanding (15).
The fourth category of naïve beliefs indicates that some participants do not have a foundational understanding of air flow in relation to the laws of physics, as in “the pressure outside the lungs is higher and so forces the air out of the lungs.” Previous studies (11–13) have underscored the significance of foundational building blocks in the prevention of misconceptions, and educators are encouraged to ensure novices are familiar with Boyle's law of pressure versus volume and factors that affect flow such as pressure differences and resistance when teaching the respiratory system. The fifth category of naïve beliefs centers round the incorrect notion that exhalation is an active process to rid the body of toxins. This correlates with studies (6, 10, 11, 12) that indicated that students have a teleological understanding of breathing. There appears to be a belief that breathing is a deliberate action and that the “body” is in control of respiration, such as “there is too much CO2 in the body and to function it needs O2.” Participants referred to exhalation as a process of “getting rid of toxic CO2,” also arguing that “we need oxygen so the lungs must expel CO2.” Sixth, students confused expulsion of air with gas exchange at the alveolar level. For example, “gaseous exchange occurs and air needs to be breathed out” could be an indication that students struggle to move between the macro and micro levels of respiration (3). Here, students confused movement of air from the atmosphere into the lungs with the micro processes occurring at the alveolar level in oxygen-hemoglobin uptake. The seventh category of naïve beliefs pertains to students' incorrect assumption that the lungs are a closed system. By stating that the “lungs and other part of the respiratory system allow breathing in and out, paralysis has to do with the spinal cord” and “the lungs will still work, they are not paralyzed,” students indicated that systems can work independently from the rest of the body. This category corroborated other similar findings (3, 4). Students seem to think that, regardless of the immobility that results from nerves not innervating muscles, the lungs will perform their function in isolation from the rest of the body. This suggests that students have not understood that muscles, nerves, and organs are all interrelated and that the lungs cannot function in isolation. We stated above that we included a category of naïve beliefs not inherently related to the structure and function of the respiratory system but rather to everyday beliefs. This last category entails unscientific assumptions, such as “[I] did community service at a Brain Injury Institute and saw a completely paralyzed person breathing on their own” and “a paralyzed person just cannot walk, otherwise they are fine,” indicating that students have not yet undergone the necessary conceptual change, as everyday experiences are reinforcing unscientific beliefs (4, 5, 18, 19). Prior conceptions are key to the process of learning (16). If a student's prior conceptions are in contrast with scientific views, it becomes difficult to undergo conceptual change, as these naïve beliefs often determine how new concepts, presented by teachers and textbooks, will be assimilated (5, 16, 18, 19).
In conclusion, our study has identified two issues pertaining to novices' reasoning processes about breathing. First, we have identified a range of naïve beliefs; second, we have established the extent of these beliefs. We further suggested reasons why they arise. As indicated above, naïve beliefs could simply be the result of lack of knowledge and should be corrected through appropriate teaching strategies. If not confronted, naïve beliefs could, however, become robust misconceptions. Hence, we recommend that educators ensure students have coherent foundational knowledge. Visual aids and three-dimensional models, which are available, can be used to facilitate three-dimensional thinking, causal reasoning, and understanding of how the respiratory organs are related to muscles and nerves. We do, however, caution against using visual aids in isolation, as visual aids are often static, simplistic, or two dimensional, thereby encouraging the construction of faulty mental models that strengthen beliefs that organs, nerves, and muscles are not interrelated. To prevent unscientific thinking and to promote conceptual change, educators are discouraged from using laymen's terminology and analogies that are oversimplistic.
It is possible that other questions pertaining to the application of respiratory physiology foundational knowledge could elicit different responses from novices and should be explored in future studies. We are aware that we may have missed subtler categories of naïve beliefs within the raw data. In a punctilious effort to ensure validity in the analysis of our data, we excluded “rich data” that appeared to be ambiguous, such as participants stating that they guessed the answer or that they could not remember. Additionally, we excluded responses where participants chose the correct answer but gave the wrong reason. We recommend that researchers use our findings and thoroughly discuss protocols with participants to probe their ambiguous and incorrect responses on a deeper level. Based on the setting of our study and the nature of our participants, our conclusions need to be tested by researchers from medical schools where students enter straight from school. We further recommend followup studies to explore whether some of the naïve beliefs identified in this study persist into later years, thus becoming robust misconceptions. Future studies should also explore teaching methodologies that can address naïve beliefs at the onset of tertiary education.
No conflicts of interest, financial or otherwise, are declared by the author(s).
E.S.B., S.M., A.A., K.B., J.F., G.G., R.F.K.-L., and H.S. conception and design of research; E.S.B. performed experiments; E.S.B., S.M., A.A., K.B., J.F., G.G., R.F.K.-L., and H.S. analyzed data; E.S.B., S.M., A.A., K.B., G.G., R.F.K.-L., and H.S. interpreted results of experiments; E.S.B. prepared figures; E.S.B., S.M., A.A., K.B., J.F., G.G., R.F.K.-L., and H.S. drafted manuscript; E.S.B., S.M., A.A., K.B., G.G., R.F.K.-L., and H.S. edited and revised manuscript; E.S.B., S.M., A.A., K.B., J.F., G.G., R.F.K.-L., and H.S. approved final version of manuscript.
The authors thank the students who participated in this study. Furthermore, the authors also thank Douglas Sias (Educational Technologist at the Faculty of Health Sciences, University of Cape Town) for preparing our instrument to be computer based and for ensuring that the participants were able to perform the necessary tasks on the computers. Finally, E. Badenhorst acknowledges the UCT URC Short Research Visit Grant and UCT Researcher Development Grant (awarded in 2012), which made it possible to travel to Erasmus University in Rotterdam, The Netherlands, to meet with S. Mamede and H. G. Schmidt in order to prepare the paper for publication.
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