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Critical thinking among environmental health undergraduates and implications for the profession.


Critical thinking is a valuable, but often overlooked, skill for environmental health professionals. Do environmental health undergraduates have the critical-thinking skills needed by their future employers? Are academic environmental health programs able to measure and improve critical thinking in their students? If critical thinking is poorly developed, what are the implications for the profession?

To begin to answer these questions, the study reported here measured critical-thinking dispositions (the attitudes and emotions brought to the task of critical thinking) among undergraduate environmental health majors at Illinois State University over a three-year period. The authors used the results, as well as what is currently known about critical thinking, to explore implications for academic programs and the profession.

Critical Thinking in the Environmental Health Profession

Critical thinking is disciplined thinking--although there is no universally accepted definition. Perhaps the best way to understand critical thinking is to consider how it is used in the environmental health profession to understand and resolve "ill-structured" problems (King & Kitchener, 1998). Some scenarios involving such problems might be as follows:

* A developer approaches a local health department with plans to build a subdivision on soil not suited to traditional septic systems, but proposes to chlorinate the discharge.

* A citizen calls a local health department to complain about "spoiled food" at a restaurant.

* An environmental health and safety manager at a hospital finds that worker-compensation claims from back injuries among nurses have increased by at least 10 percent per year for the past five years, even though five patient-lifting devices were purchased three years ago.

There is probably no one best approach to investigating and solving these problems. Yet some approaches are clearly better than others. Critical thinking helps us find these "better" approaches. A critical thinker is able to "assess the credibility of a source of information" (Facione, 1998). In Scenario 1, for example, a critical thinker would evaluate the credibility of the developer's claim about the proposed septic systems. Is the claim based on the opinion of the developer, the opinion of a septic system expert, laboratory test data, or actual field experience with the unit? In Scenario 2, a critical thinker will recognize uncertainty in witness memory and will seek corroborating information such as the testimony of other patrons, food samples, or environmental conditions (such as salad bar temperatures).

A critical thinker also is able to "recognize a problem and describe it without bias" (Facione, 1998). For example, with poorly developed critical thinking, a manager in Scenario 3 might describe the problem as one of stubborn and lazy employees who resist change even when it is to their advantage, rather than recognizing that there must be one or more underlying problems that have not been addressed by the purchase of lifting devices.

Critical thinkers take both a broader and a deeper view of any problem or condition. This leads to an ability to anticipate "the implications of a position someone is advocating" (Facione, 1998). In Scenario 1, for example, chlorination units may require routine maintenance by the resident. A critical thinker recognizes that, in the absence of systems to ensure that the maintenance is performed, many units will stop functioning properly when maintenance is neglected.

Most importantly, critical thinkers are aware of their own thinking and seek to improve it; they "apply their powers of critical thinking to themselves" (Facione, 1998). Everyone has biases and limitations. Critical thinkers understand their biases and limitations and constantly monitor their thinking to minimize errors.

Critical-Thinking Dispositions

To put a skill to use, one must have both the skill and the inclination to use (Perkins, Jay, & Tishman, 1993). Research suggests that the desire or inclination to use critical thinking is reflected in a number of personal attributes, known as critical-thinking dispositions. These dispositions are explained in Table 1.

An environmental health professional with well-developed critical-thinking dispositions--and the skills to act on those dispositions--can be a powerful force for effectiveness and improvement in environmental health efforts. Conversely, a professional with poorly developed critical-thinking dispositions will be ineffective, or worse. Consider the following description of a person with poorly developed critical-thinking dispositions:
 [I]s not interested in the facts, prefers not to think, mistrusts
 reasoning as a way of finding things out or solving problems ... is
 closed-minded, inflexible, insensitive, can't understand what others
 think, is unfair when it comes to judging the quality of arguments,
 denies his or her own biases, jumps to conclusions or delays too long
 in making judgments, and never is willing to reconsider an opinion
 (Facione, 1998, p. 9).

Sound like anyone you know? Although the combination of attributes described above is extreme, most of us probably recognize some of these traits in others, and even ourselves!


The California Critical Thinking Disposition Inventory (CCTDI) is a 75-item instrument designed to measure one's overall disposition toward critical thinking and the seven specific dispositions listed in Table 1 (Facione, Facione, & Giancarlo, 2000). It produces one subscale for each of the dispositions as well as a combined score. On each subscale, a score above 50 indicates strength in that disposition (the target). A score below 40 indicates weakness, while a score below 30 indicates a negative disposition. For the combined score, a value of 350 indicates overall strength (the target), while scores below 280 indicate weakness and scores below 210 indicate an overall negative disposition. The validity and reliability of the CCTDI as a measure of critical-thinking dispositions has been well established (Facione, Facione, & Sanchez, 1994).

A pre-test, post-test research design is used in the Department of Health Sciences at Illinois State University to assess the change in critical-thinking dispositions while students are enrolled in the major. The data reported here reflect only the pre-test portion of this ongoing project. A follow-up article will be published once more data become available. The authors began using the CCTDI in an introductory environmental health course in the spring semester of 2000. Students who take this introductory course range from freshman to seniors depending on when they become majors. Students in other Department of Health Sciences majors (clinical laboratory science, health education, health information management, and safety) also completed the inventory in their introductory courses.

All inventories were administered by the same person using an established protocol. Student responses are not anonymous, so students were asked to sign a consent form if they chose to participate (to date, fewer than 5 percent of students have elected not to participate). Student demographic and academic information was obtained from university records. Analyses were conducted with SPSS 11.0 for Windows (SPSS, Inc., Chicago). A critical value of p [less than or equal to] .05 was used for all statistical-significance tests.


A total of 198 health sciences majors had completed the CCTDI instrument as of the fall 2002 semester. Of these, 52 were environmental health majors. The average overall CCTDI score for environmental health majors was 308. Only 7.7 percent scored 350 or higher, a level considered to indicate strength in critical-thinking disposition. A total of 15.4 percent had scores indicating overall weakness in critical-thinking disposition (under 280). These results are comparable to results for other undergraduates in the United States and Canada (Bers, McGowan, & Rubin, 1996; Colucciello, 1997; Walsh & Hardy, 1999; Wilson, 2000). Unfortunately, the results demonstrate that relatively few environmental health majors are bringing strong critical-thinking dispositions to the profession.

Table 2 summarizes results for environmental health majors for specific critical-thinking dispositions. Students tended to be strongest in open-mindedness, analyticity, inquisitiveness, and maturity. Yet, even in these areas, no more than about one in four students demonstrated strength. Conversely, about half the students demonstrated weakness in truth seeking and systematicity.

Table 3 compares environmental health students to those in other health sciences majors on the basis of demographic and academic characteristics. A majority of environmental health majors are male (57.7 percent) while other majors are predominantly female (74.7 percent). The two groups are comparable in terms of age, credit hours earned at ISU, credit hours transferred from other schools, and total credit hours. Results for total credit hours indicate that the average health sciences major does not take the introductory course in his or her major until the junior year. In terms of academic characteristics as measured by high school GPA, high school class percentile, and cumulative ACT score (the college placement test preferred by ISU), the two groups are comparable. The, ISU GPA, however, is significantly lower for environmental health majors. It is unclear whether this circumstance is due to a basic difference in academic ability or in the courses that students are required to take. The fact that the students are comparable in all others measures of academic ability and that environmental health majors actually score somewhat higher on ACT science reasoning suggests that the difference in GPA may be due to curriculum differences.

The critical-thinking dispositions of environmental health majors and all other majors are compared in Table 4. (Because of deviation from normality in the results for some critical-thinking dispositions, statistical significance was tested with both a two-tailed t-test and a Mann-Whitney U test--a nonparametric equivalent of the t-test). Truth seeking scored the lowest of the critical-thinking dispositions among both environmental health majors and all other majors. This observation agrees with other studies (Bers, McGowan, & Rubin, 1996; Colucciello, 1997; Walsh & Hardy, 1999; Wilson, 2000). Environmental health majors on average scored 2.5 points higher in open-mindedness (p = .014) and 1.9 points higher in maturity (p = .035) than all other majors. No statistically significant differences were observed between the environmental health majors and other health sciences majors in other critical-thinking dispositions. Environmental health majors on average scored 8.2 points higher in overall critical-thinking-disposition scores, although this difference was not statistically significant.

The bivariate relationship between the student's overall disposition and each of the demographic and academic variables is explored in Table 5. Critical-thinking disposition does not appear to be significantly related to any of the variables except for total credit hours and age. The relationship with these variables is positive, indicating that, on average, older students and those with more college credit tend to have higher critical-thinking-disposition scores. Note, however, that age and total credit hours are correlated (R = .637), raising the question of whether only one of these variables is truly related to critical-thinking dispositions (the other would then correlate with critical-thinking disposition only because of a confounding effect).

Indeed, subsequent analysis showed that total credit hours rather than age is related to critical-thinking dispositions. This relationship was found through a multiple-linear-regression analysis, presented in Table 6. After the factor of total credit hours was introduced into the model, the relationship between age and overall disposition weakened substantially (as measured by slope--a decrease from .972 to .382). The overall explanatory power of the model also improved (an increase of R from .157 to .194). On the other hand, adding age to the model produced relatively little change in the relationship between total credit hours and overall disposition (as measured by slope--a change from .081 to .064) and little improvement in the explanatory power of the model (a change of R from .189 to .194). These results indicate that the relationship between total credit hours and overall disposition is more likely to be causal. Age may actually have little or no causal relationship with critical-thinking dispositions.


On average, undergraduate environmental health majors at Illinois State University were positively disposed toward six of the seven critical-thinking dispositions, although less than one-quarter of students could be considered "strong" in any of the dispositions. On average, undergraduates were negatively disposed toward truth seeking, suggesting that they oppose seeking knowledge that threatens their preconceptions or interests. Although scores were comparable to those of other health sciences majors and to other undergraduates in North America, the results suggest a significant potential problem for the profession. Environmental health professionals face ill-structured problems on a regular basis, from assessing and controlling public health risks to resolving disease outbreaks. New professionals who have difficulty applying critical thinking skills to these problems jeopardize the effectiveness and future improvement of environmental health programs.

Improving the critical thinking of students and new professionals should be a priority, but will not be easy. One reason for optimism in light of these results is that college experience (total credit hours) appears to be the most influential factor among those examined in the study reported here. The challenge is to make the most of that experience. Another reason for optimism is that critical-thinking dispositions do not appear to be strongly related to any measure of academic performance, including GPA, ACT score, and high school rank, a finding consistent with findings of other studies (Bers, McGowan, & Rubin, 1996; Facione, Sanchez, Facione, & Gainen, 1995), and with research indicating a lack of correlation between intelligence and dispositions (Perkins, Farady, & Bushey, 1991; Perkins & Tishman, 1998). Therefore, evidence suggests even average students can develop strong critical-thinking dispositions.

On the other hand, little is known about the factors that have the greatest influence on critical-thinking dispositions. The factors examined here could explain only about 4 percent of the variation in the critical-thinking-disposition scores of undergraduates. Instead, it is likely that experiences in the home, prior schooling, and similar factors play a major role. Environmental health academics and professionals can do little to change such factors. Nevertheless, academics have the opportunity to make a difference in the critical-thinking dispositions of students.

Recommendations for Academic Programs

What inhibits development of critical-thinking dispositions? Palmer (1998) observed that the greatest impediment to the development of thinking is fear. "Students ... are afraid: afraid of failing, of not understanding, of being drawn into issues they would rather avoid, of having their ignorance exposed or their prejudices challenged, of looking foolish in front of their peers" (p. 37). What Palmer describes here is the realization that while schools and universities are supposed to be great institutions of learning--and in many ways they are--the teaching and learning process in schools also can be frightening, retarding the growth of critical-thinking dispositions.

In addition, the environmental health program at Illinois State University is probably like similar programs at other universities in that the curriculum tends to be dominated by the knowledge and the basic skills graduates will be expected to have for entry-level positions and certification examinations. With this emphasis, critical thinking receives neither the time nor the emphasis it deserves. It rarely serves as a fundamental factor in the design of a course.

With this situation in mind, we make several practical recommendations for instructors in environmental health programs that could improve the critical-thinking dispositions of students:

* Recognize and reward intellectual "risk-taking" by students. Show genuine and public appreciation when students question current practices, offer new ideas, use sources beyond required material, question assignments, and challenge the instructor's positions.

* Design critical thinking into assignments. Even in content-oriented assignments, ask students to question the credibility of sources, identify gaps in the knowledge base, critique an author's argument, or explore how different people might use the same facts to come to different, well-reasoned conclusions.

* Encourage students to express, and then question, their thinking (Savage, 1998). Given the intellectual fear felt by many students, this undertaking is likely to require considerable effort and a variety of techniques. Since few students are comfortable expressing their thoughts to an entire class, use alternatives like journals, in-class written assignments, small discussion groups, and electronic that rooms (Phillips, 2001).

* Model the behavior. A skill is often learned best by watching others perform it. Instructors can demonstrate critical-thinking dispositions by raising questions about their own thinking and taking time to explain how they made decisions (Elder & Paul, 1998).

* Use real-life experiences. Experiences of this type provide many benefits (Bierma & Krishnan, 1997), and critical-thinking dispositions can be enhanced by forcing students to face the types of decisions they might face on the job. The authors have implemented this recommendation on a limited basis. For example, students in the ISU pollution prevention course have worked with local manufacturers to reduce waste. Students in the air quality and industrial-hygiene courses have performed air quality and noise investigations for local companies. Students in the waste management course have conducted waste audits for the university. In activities of this sort, students quickly confront the problem of questionable information sources, the difficulty in clearly defining the problem or research question, the importance of an organized and systematic approach to the problem, and the need to persevere despite setbacks and complexities. The authors have found that real-life experiences tend to be self-motivating for students, which tends to reduce the fear of intellectual risk taking.

* Use simulations. When real-life experiences are not feasible, lifelike substitutes may be possible. For example, ISU students conduct a mock hearing in which they must develop their side of an environmental health legal case, including testimony and evidence. They take the roles of attorneys, witnesses, and hearing officers. Students also conduct a mock hearing in the toxicology class, arguing over a proposed development project and potential chemical exposures associated with it. Games and simulations can re-create the types of decision-making circumstances that require critical thinking.

* Measure students' critical-thinking dispositions. Data reported in this study are the pre-test portion of a pre-test/post-test research project designed to assess change in critical-thinking dispositions while students are enrolled in the major.


During the study reported here, the critical-thinking dispositions of environmental health undergraduate students at Illinois State University were found to have significant shortcomings. Although improving the critical thinking of students will not be easy, results indicated that college experience (total credit hours) appears to be the most influential factor among those the authors examined. In addition, critical-thinking dispositions did not appear to be strongly related to any measure of academic performance in this study, suggesting that even average students can develop strong critical-thinking dispositions. Academics thus have the opportunity to make a difference in the critical-thinking dispositions of students.
TABLE 1 Critical-Thinking Dispositions and Examples (a)

Disposition Example

Truth seeking Courageous desire for the truth
 Values the truth over preconceived opinions,
 personal interests, or "winning an argument"
Open-mindedness Understands and respects the thinking and opinions
 of others
 Tolerant of and willing to consider new ideas and
Inquisitiveness Values being well informed about a wide range of
 Wants to know how things work and how they could be
Analyticity Anticipates possible problems or consequences
 Persistent in understanding a problem, even when it
 is difficult or complex
Systematicity Strives to approach issues in an orderly, organized,
 focused, and diligent way
Critical-thinking Understands own biases and limitations
 self-confidence Trusts in own ability to make well-reasoned
 judgments, despite biases and limitations
 Believes that others trust one's ability to make
 well-reasoned judgments
Cognitive maturity Recognizes when critical thinking is required and
 when it is not
 Understands that ill-structured problems may have
 more than one well-reasoned solution
 Recognizes the need to reach closure even in the
 absence of complete knowledge

(a) Adapted from Facione (2000); Facione, Facione, & Giancarlo (2000).

TABLE 2 Percentages of Environmental Health Students Displaying
Different Degrees of Critical-Thinking Dispositions (a)

 Neither Strong
Subscales Weak (<40) Nor Weak (40-50) Strong (>50)

Truth seeking 51.9% 48.1% 0.0%
Open-mindedness 9.6% 65.4% 25.0%
Inquisitiveness 5.8% 67.3% 26.9%
Analyticity 13.5% 61.5% 25.0%
Systematicity 44.2% 51.9% 3.8%
Confidence 25.0% 65.4% 9.6%
Maturity 11.5% 61.5% 26.9%

(a) Illinois State University, 2000-2002. Sample size = 52.

TABLE 3 Demographic and Academic Characteristics of Environmental Health
Majors, Compared with Those of All Other Majors in the Department of
Health Sciences (a)

 Environmental Health All Other Majors by
 Majors (n = 52) (n = 146) t-test (b)
 Mean SD Mean SD p

Gender (% female) 42.3 NA 74.7 NA <.001 (c)
Age (years) 22.0 4.1 22.1 4.6 .967
ISU credit hours 68.6 22.6 74.9 34.9 .222
Transferred credit 38.6 29.3 30.8 40.9 .210
ISU GPA 2.30 1.03 2.81 0.61 .001 (c)
High school GPA 3.15 0.56 3.17 0.41 .809
High school 64.0 19.1 68.4 15.4 .202
ACT Composite 21.5 3.0 20.8 3.0 .223
ACT Science 22.2 3.1 21.0 3.1 .036 (c)
ACT English 20.7 3.8 20.3 3.9 .566
ACT Math 21.0 3.8 20.3 3.5 .318
ACT Reading 21.8 4.3 21.3 3.9 .553

(a) Illinois State University, 2000-2002.
(b) p-values were obtained by t-test except for gender comparison, for
which Chi-square tests were performed.
(c) Difference is significant at the .05 level.

TABLE 4 CCTDI Scores of Environmental Health Majors, Compared with Those
of All Other Majors in the Department of Health Sciences (a)

 Difference by
 Environmental All Other Difference Mann-Whitney
 Health Majors Majors by t-test U-test
 Mean SD Mean SD p p

Truth seeking 38.0 6.4 36.9 5.6 .226 .133
Open-mindedness 46.4 5.3 43.9 5.7 .006 (b) .014 (b)
Inquisitiveness 47.1 6.0 46.0 6.2 .289 .579
Analyticity 45.2 5.8 44.2 5.4 .262 .398
Systematicity 40.3 6.6 41.2 6.7 .428 .470
Confidence 44.3 6.3 43.0 6.6 .194 .165
Maturity 46.5 6.7 44.6 6.0 .049 (b) .035 (b)
Total 307.9 27.9 299.7 27.5 .068 .160

(a) Illinois State University, 2000-2002.
(b) Difference is significant at the .05 level.

TABLE 5 Relationship Between Overall Critical-Thinking-Disposition Score
and Each Demographic or Academic Variable (Bivariate Analysis) (a)

Independent Variables R Beta p

ISU GPA .051 -1.817 .479
Total credit hours .189 0.081 .008 (d)
High school percentile .036 -0.062 .681
ACT .076 0.707 .361
Age .157 0.972 .027 (d)
Gender (b) .043 -2.50 .550
Group (c) .130 8.174 .068

(a) Illinois State University, 2000-2002.
(b) Female = 1; male = 0.
(c) Environmental health major = 1; non--environmental health major = 0.
(d) Difference is significant at the .05 level.

TABLE 6 Results of a Multiple Linear Regression on CCTDI Total Score of
Department of Health Sciences (a)

 Beta R p

Model .194 .023 (b)
Independent variables
 Age 0.382
 Total credit hours 0.064

(a) Illinois State University, 2000-2002.
(b) Model is significant at the .05 level.

Acknowledgements: The authors gratefully acknowledge the contributions of Timothy Kelley, George Byrns, and Barbara Broadbear to the research and the manuscript.


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Guang Jin, Ph.D., P.E.

Thomas J. Bierma, M.B.A., Ph.D.

James T. Broadbear, Ph.D., C.H.E.S.

Corresponding Author: Guang Jin, Assistant Professor of Environmental Health, Department of Health Sciences, Illinois State University, 305 Felmley Hall of Science, Campus Box 5220, Normal, IL 61790. E-mail:
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Title Annotation:Features
Author:Broadbear, James T.
Publication:Journal of Environmental Health
Geographic Code:1USA
Date:Oct 1, 2004
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