Originally published at Child Myths
© Jean Mercer, 2009.
Contact Prof. Mercer at Jean.Mercer@stockton.edu

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Introduction

This paper deals with teaching issues and on the use of critical thinking concepts as they apply to the understanding of child development.

Developmental psychology, developmental science, child development, childhood and adolescence, lifespan development: all these terms can be used for courses that attempt to teach how developmental change functions in humans from conception through adolescence. Why so many different names?

Part of the answer has to do with the ways course materials are organized and divided, but more is related to rapidly changing characteristics of a field that is quite different from what it was fifty years ago. A changing field creates a challenge for instructors, but the study of child development (to choose one of the labels) presents other challenges too.

Child development courses involve more natural science components than other psychology courses, with the exception of physiological psychology and of sensation and perception. Students, and even instructors, may find it unexpectedly difficult to master neuroscience and genetics concepts for which they may have little background. Research design and its implications are essential to the understanding of causal factors in child development, but few psychology curricula have statistics or research methods as prerequisites for child development courses, even though variability is at the heart of any discussion of development.

These natural and mathematical science aspects of child development courses are particularly difficult to combine with more value-related material ("how should parents behave?") or material with immediate practical effects ("how should schools be run?") Further challenges arise because of expectations and beliefs about development which students bring into the class. One problematic expectation is that everyone's personal experiences are a good background for study of child development -- that in fact everyone, having been a child, already knows a good deal about developmental change in childhood. However, although students think they have a lot of knowledge about development, the evidence seems to be that adults actually have a rather poor understanding of development, especially of its social and emotional aspects (Daniel Yankelovitch Group, 2000). Complex material like developmental science requires a high level of critical thinking for mastery.

In this paper, I will discuss some important critical thinking issues relevant to the teaching of child development courses, and will propose some practices that may help harness critical thinking skills and improve student understanding.

What is Critical Thinking? And Why Do We Care?

Critical thinking is thought that uses a set of skills specialized for evaluation of evidence and of logical processes that support or fail to support conclusions. The alternative approach, uncritical thinking, accepts evidence and logic that would be rejected if critical thinking skills were applied to the information. In academic circles, critical thinking skills are considered to be highly desirable, but it is unlikely that any human being manages to use such skills on every occasion when they are called for. In fact, avoidance of critical thinking seems more characteristic of human beings -- and more comfortable for them -- than its use. As J.A.C. Brown (1963), a student of techniques of persuasion that combat critical thinking, commented, most people want to feel that issues are simple rather than complex, to have their prejudices confirmed, and to find an enemy to blame for their frustrations. To satisfy those common desires usually requires uncritical thinking.

As teachers of developmental science, we would like to move our students away from the characteristics Brown noted. We would prefer for them to do the following, all of which require critical thinking:

1. Understand that human issues are complex.

2. Become willing to examine their own assumptions.

3. Realize that humans behave and may even develop in varying ways, but all share some aspects of human development.

4. Minimize the use of developmental science material to sermonize against "the wrong", while remembering that understanding of development can improve outcomes. In considering our situation and goals, we would do well to realize that other disciplines are experiencing similar problems.

Natural scientists, in particular, are concerned that "[v]ast numbers of adults fail to take a scientific approach to solving problems or making judgments based on evidence. Instead, they readily accept simplistic answers to complicated problems..." (Alberts, 2009, p. ). In the hope of encouraging students to use critical thinking, natural scientists have set goals for science education such as knowing science facts, generating and evaluating evidence and explanations, understanding the nature and development of scientific knowledge, and participating in scientific practices and discourse (Alberts, 2009; Moore, 1999). Except for the simple knowledge of facts, these goals also require critical thinking. We cannot devote a semester of a child development course to instruction in critical thinking, but we can give some consideration to reasons for uncritical thought, and to the ways that improvements in critical thinking can improve student understanding and retention of the material they study.

General Critical Thinking Skills

A set of critical thinking skills can be considered as generally applicable to assessment of information, including information about developmental science. Some are more likely than others to be demanded in a first undergraduate course in child development.

Inference. Inference is the skill of discriminating among degrees of truth or falsity of conclusions drawn from given data. While this is a particularly important skill for developmentalists at more advanced levels, few students in the first undergraduate course are called upon to make inferences. Such courses rarely involve examination of data or reading of research articles in professional journals. In addition, inference as carried out in developmental science generally involves statistical analysis, and statistics or research methods courses are usually not prerequisites for the first child development course.

Recognition of assumptions. This critical thinking skill involves the detection of unstated assumptions or presuppositions in given statements or assertions, including, of course, those the person makes himself or herself. Recognition of assumptions is an important skill for students of developmental science, as common beliefs frequently contradict empirical research about development; students who cannot recognize their own a priori beliefs may become confused by what they see as the unlikely results of systematic investigation.

Deduction. The critical thinking skill of deduction involves determining whether certain conclusions necessarily follow from given information. Deduction is an essential aspect of developmental science, and is especially relevant to questions about correlation and causality. As most students do not enter the first course with a background in statistics and research design, coursework may need to emphasize ways in which developmentalists examine conclusions.

Interpretation. The critical thinking skill of interpretation stresses the weighing of evidence and determining whether generalizations or conclusions based on the evidence are warranted. This skill, so important for more advanced developmentalists, is only at its beginning in younger students. Textbooks offer little specific evidence and less evaluation of the source of the evidence, and research reports are generally too complex and difficult for undergraduates to read. Study of research design is needed before most students can evaluate evidence effectively. However, instructors can model evaluation of evidence by discussing research designs as they have been used in the study of child development. Thoughtful Internet assignments may also be valuable in development of this skill.

Evaluation of arguments. This aspect of critical thinking involves distinguishing between arguments that are strong and relevant and those that are weak or irrelevant to a question. Before students can evaluate arguments, they must abandon the position that all evidence is equal, and the belief that it is inappropriate and intolerant to reject someone's argument. Practice and feedback from the instructor or classmates are helpful supports for development of this skill, but these are rarely provided in child development courses. When students' performance is evaluated through multiple choice examinations, feedback about irrelevant arguments is quite infrequent. Instructors who want to encourage the development of evaluative ability must commit themselves to dealing with extensive written assignments. Attention to detail is a necessity for critical thinking, and assignments cannot reveal the presence or absence of critical thinking unless they themselves display reasoning in detail.

Attempts have been made to design courses that will improve critical thinking with respect to the study of psychology. Lawson (1999) designed a course that guided study of experimenter bias, single versus multiple causation, correlation as opposed to causation, the use of comparison groups or measures, and the problem of confounding variables. Penningroth and her colleagues (Penningroth, Despain, & Gray, 2007) put together a one-credit course intended to improve psychological critical thinking. These efforts are obviously relevant to the enhancement of critical thinking about developmental science, but the latter topic requires emphasis on additional specific issues that are not necessarily important to the general field of psychology.

Why Do We Want Child Development Students to Develop Critical Thinking?

With respect to learning during a course in child development, it is desirable for students to use critical thinking skills, as such skills will help them to understand how to apply what they learn. Critical thinking skills also help students avoid confusion between related or similar concepts; clarifying material through critical thinking helps students to understand and remember correctly what they have studied. And, of course, application of critical thinking skills helps solve the old problem of "not knowing what's important."

In addition, we want students to have critical thinking abilities that are of special importance to child development information, so that they will continue to use a critical approach to developmental issues long after they have forgotten exactly what a Fels multiplier is.

Most students will be parents and have the responsibility for choosing schools, medical and psychological treatments, and parenting practices that will influence their children. As one interview study of young parents has shown, parental understanding of early development is spotty at best (Daniel Yankelovitch Group, 2000). Many students will be teachers, participate in choices of academic and social curricula, and interpret tests and behavior. Some students will be attorneys and judges making decisions about child custody and juvenile justice, tasks which will demand some ability to think critically about developmental issues. Some students will be legislators deciding on laws and on funding of family and school services; if these can bring critical thinking skills to their consideration of developmental outcomes, the community will benefit. Some students will be physicians, psychologists, and social workers whose critical thinking skills will directly affect children; they may also be the authors of systematic research syntheses on which other practitioners will depend for their choice of treatment approaches.

Finally, of course, a few students will be members of the Society for Research on Child Development, and the developmental scientists of the future.

Why Don't Students Already Think Critically?

I will take it for granted that undergraduate students need to improve their critical thinking abilities. Although research in this area is complicated by the fact that few humans ever perfect this set of skills, so it is hard to choose a comparison group, recent work suggests that even professional psychologists with graduate training may be far less competent in critical thinking than we would like to see (Sharp, Herbert, & Redding, 2008). The remarkable difficulties shown by adults who need to ignore irrelevant information have been demonstrated for many years, beginning with the work of Tversky and Kahneman (1974). Superficial information included in a question confuses many adults (Waldrop, 1987).

What factors limit the critical thinking skills of professionals, those of other adults, and, we can assume, those of undergraduates? Some of these factors are developmental in nature, while others involve past and present instruction, intentional or otherwise.

Formal Operations and Horizontal Decalage

The study of formal operational thought by Piaget (1922) provided some important insights into critical thinking. Formal operational thinkers can create a variety of hypotheses as possible explanations for an event and can figure out experimental tests to support or reject a hypothesis. In addition, they are able to co-ordinate factors rather than having to consider each one separately, allowing them to deal with issues like rates or proportions. They can also collect data systematically and consider sources of error and the possibility that their conclusions are wrong. Without all these abilities, critical thinking would be much impeded.

Students in undergraduate child development courses are generally at least in the sophomore year of college, and the youngest are about 20 years old. The textbooks we assign them state that they have had the ability for formal operational thought for some years, and surely formal operational thought is the foundation of many critical thinking abilities. However, anyone who has attempted to teach undergraduates what formal operational thought is, must have become very aware that the students did not seem to bring formal operational abilities to the study of formal operations. Demonstrations or videos showing the use of ratios and isolation of variables are commonly met with anxious student faces, behind which are anxious minds questioning whether they themselves are able to do the tasks represented as possible for 12-year-olds.

Piaget's concept of horizontal decalage is an important part of the explanation of apparent delays in formal operational thought. This concept suggests that cognitive abilities can appear to be less uniform than we expect, depending on the familiarity of a problem for a student. Unfamiliar material is less easily treated with formal operational or other high-level cognitive abilities than is familiar material; for example, as Burbules and Linn (1988) demonstrated, reasoning ability can be improved simply by free exploration of a situation. Characteristics of infants and children are relatively unfamiliar for most undergraduates in the United States; small families and intense age-grading have prevented them from having much opportunity to observe younger children. It would be surprising if undergraduates were able to apply critical thinking skills to child development information as they can to, say, cooking, or repairing a car.

For developmental reasons, then, it is unlikely that students in undergraduate child development courses will be able to muster formal operational skills without help or effort, and thus unlikely that they will be able to use critical thinking abilities effectively throughout the course.

The Perry Scheme

There have been relatively few discussions of cognitive changes that occur during the college years. One approach to this topic, based on a small number of students at Harvard, offers some ideas that are intriguing although somewhat speculative. The "Perry scheme" (Perry, 1970) proposed stages of undergraduate development with strong relevance to critical thinking. Perry proposed that entering freshmen tend to focus their thinking on the idea that there are right and wrong answers, known to authorities; this position is referred to as "Dualism/Received Knowledge."

Perry suggested that the initial, basic attitude is that all problems are solvable, and the student's task is to learn the right solution. A second step in this dualistic position has to do with attitudes toward authorities. Some authorities (for example, literature professors) are seen to disagree, whereas others (like physicists) are believed by the student to agree. Those authorities who have agreement about right answers are the ones to pay attention to. (It seems doubtful that developmental scientists are considered to be among those who agree on right answers.) Critical thinking by the student is not an option.

A second position, taken by students who have passed the dualistic freshman stage, is one that acknowledges conflicting answers, but concludes that the existence of conflict means that only one's own intuitive response is correct, and external authorities are not correct. Perry referred to this position as "Multiplicity/ Subjective Knowledge." Students at the beginning of this position assume that there are problems whose solution is known, and others whose solution is not known; the student's job is to find the right solutions that are known. Later, a new assumption appears: most problems have no known solution, so either everyone has a right to their own opinion, or it doesn't matter which solution you choose, and the student's task is to amplify on these points rather than to try to solve the problems. Critical thinking would be a waste of time, and opinions are nothing more than unexamined prejudices.

A third position described by Perry develops out of the first two. This position, called "Relativism/Procedural Knowledge", is a step that makes critical thinking possible. It includes the idea that there are reasoning methods favored by disciplines, and that study of a discipline requires mastering these as well as amassing a supply of facts. Subjective responses are considered, but separated from techniques of objective analysis. In the initial step for this position, "Contextual Relativism", the student acknowledges that there are reasons for all proposed solutions to problems, and that solutions need to be examined in context and relative to the type of support they have. Although solutions may be equally good, one may be better than others in a given context. The student's job is to learn to evaluate solutions -- a matter requiring critical thinking skills.

Contextual Relativism would seem essential to the serious study of developmental science, an area in which multiple causes are responsible for multiple outcomes, and dynamic systems theory suggests that nonlinear relationships are common. Value-laden aspects of developmental studies also make it important that students have the understanding of subjective responses characteristic of this period of development.

"Relativism/Procedural Knowledge" is not the last step in Perry' scheme, but it may be the lowest level that allows for mobilization of critical thinking skills, and thus the first level that permits good understanding of the complexities of developmental science. It is not clear how we can persuade or push students to arrive at this level, however, nor can we make it a prerequisite for enrollment in a child development course.

Students' Past Experience

College students who received their secondary education in the United States have generally received some encouragement to think critically and may believe that they are accomplished at critical thinking tasks. However, examination of secondary school experiences suggests that these may diminish rather than foster critical thinking abilities. Some years ago, the novelist Francine Prose examined efforts toward critical thinking used in high school English textbooks and other assignments (Prose, 1999). In her article, aptly named "I Know Why the Caged Bird Cannot Read", she noted a failure to require close, line-by-line reading, and a tendency to questions about social or moral implications rather than about the actual content of the novel. Prose referred to one teacher's manual that asked students reading Huckleberry Finn to count the ways in which Mark Twain negated the humanity of the slave character Jim, rather than comparing the number of such incidents with the number in which his humanity was witnessed. Prose also noted the frequency of assignments in which questions asked were peripherally relevant to the information available to the student.

For example, students might be asked what a character might do about a situation not mentioned in the book. Similarly, students might be asked to answer questions whose answers they would be unlikely to know, such as a question about the mental health prognosis of the heroine of The Bell Jar. Assignments of these types discourage a focus on relevant, available information, and encourage the view that all possible answers (if long enough) are acceptable.

College students who have experienced high school assignments of the kind Prose described are likely to feel comfortable with irrelevancies and low levels of abstraction, and even to believe that they are excellent critical thinkers because of their handling of such matters. Facing a child development course, with its demands for identification of relevant information and for evaluation of ideas and practices, such students may feel offended, even humiliated by their perceived failure to succeed with the methods they have been rewarded for.

Seductive Ideas

Kagan's fascinating book, Three seductive ideas (2000), discussed a number of common preconceptions that interfere with understanding of psychology in general and the study of development in particular. These "seductive ideas" are broad assumptions about the nature of human beings, and when they are unrecognized or incorrectly applied, they can well create confusion about material commonly included in the teaching of developmental science.

Kagan proposed that one important "seductive idea" was abstractionism, the assumption that if two phenomena have some characteristics in common, these characteristics can be abstracted and used to reason from one phenomenon to the other. For example, as animals and human beings have certain things in common, especially in their early lives, the application of abstractionism would suggest that whatever is true about young animals can also be expected to be true about young humans. Similar reasoning can be applied to brain and mind, with the assumption that whatever is shown to be true about brain processes can also be assumed to be true about mental processes. Both of these applications of abstractionism have the potential for confusing thinking about development.

A second "seductive idea" is infant determinism. This is the assumption that in all aspects of development, early events influence outcomes more powerfully than later events. The assumption of infant determinism can cause confusion about the nature of plasticity by blurring the distinction between experience-expectant and experience-dependent plasticity, as well as by convincing students that a reliable principle makes it unnecessary for them to examine the evidence about the effects of experience.

The third major "seductive idea" mentioned by Kagan is the pleasure principle. The belief that motivation is determined by the pursuit of gratification (and, perhaps, by avoidance of discomfort) is at odds with a number of important ideas about development. For example, difficulties in teaching of Piagetian concepts are confused by student application of the pleasure principle, as students search for ways in which infants "must" be positively reinforced for cognitive developments. Similarly, the idea of mastery motivation as a general principle, and of attachment behavior as seen from an ethological viewpoint, are difficult to comprehend when the pleasure principle is a starting point for thinking.

"Folk Psychology"

Not all "seductive ideas" are broad generalizations. Some are specific beliefs, common currency of thought about development and reinforced by repetition in the media and in casual conversation. There are probably hundreds of these claims that "everybody knows" and few approach critically. Here are some examples of folk or naïve developmental psychology (Mercer, 2009):

• Sugar causes hyperactivity (which is, incidentally, the same thing as hypertension).
• Toddlers drop food off their high chairs because they want to make their parents mad.
• Teenagers learn to be antisocial under peer pressure from bad companions.
• Autism "clusters" mean that something in a local environment causes the disorder.
• Breastfeeding causes a baby to become attached to her mother.

These common beliefs contradict and confuse understanding of evidence-based information about development. Addressing them directly and modeling critical thinking for students may help to lessen their potential for damage.

Mass media and other sources of information

Newspapers, television, and other media sources repeat much incorrect information which they garner from each other. This is especially true with respect to any topic which is "flavor of the month", as is the case currently for attachment. The television program "20/20" recently presented a show which uncritically described the practice of keeping adopted children within three feet of a parent at all times, night and day, for a number of weeks.

"Made for TV" movies have dramatized similar ideas. In addition, materials written for parent or child care use may be quite unreliable; for example, a pamphlet distributed to child care workers (Koralek, 1999; still in use) claimed that securely attached children will usually not be upset when dropped off at day care, and that they will smile and show interest in other people -- questionable statements unless they are accompanied by information about the age and circumstances of the children.

Problems in the Classroom: Critical or Uncritical Thinking?

We have considered what developmental issues and what experiences may make it difficult for undergraduate students of child development to think critically. It is unpleasant but important to ask whether there are also factors in coursework that encourage uncritical thinking about development and discourage critical thinking.

Coursework and Assessment

One possible factor has to do with the types of assignments and particularly of assessment approaches used by instructors. Unless they are carefully discussed and analyzed at some later time, multiple-choice tests do little to encourage critical thinking; even though very good multiple-choice examinations may require the instructor to think analytically, they do not have the same effect on students.

Essay assignments and examinations have a far greater potential for revealing student thinking patterns and providing opportunities for encouraging critical thinking, but this potential is realized only if instructors devote themselves to providing feedback -- and, of course, if students pay attention to it. Small classes may offer opportunities for oral discussion with critical thought about evidence and reasoning, but instructors may find appropriate responses difficult, and students may resent having their thinking dissected in public. Instructors can model critical thinking by commenting at length on issues, but of course this takes away time from "covering" other points. All the solutions available to instructors involve trade-offs between encouragement of critical thinking and the achievement of other goals for the class.

Trouble with Textbooks

In addition to instruction, discussion, and assessment methods, faculty members have some choice of textbooks for developmental science courses, but there are some serious difficulties involving these books. Almost all of them are beautifully produced, colorful and interesting to look at, and engagingly written, with many vignettes about specific children and rich description of some events in development. They are loaded with "features", boxes discussing research issues, thought questions of various kinds, and attempts to engage the student by raising questions about real-world applications. Regrettably, however, many of them provide no more impetus for critical thinking than did the high-school assignments discussed by Francine Prose.

I have chosen some quotations from a very popular textbook which had best be nameless, especially because it is really no worse than its competitors. As the reader will see, both statements and questions fail to use or trigger critical thinking skills.

"...theories have contributed to new approaches to education that emphasize exploration, discovery, and collaboration. As a result, children express greater enthusiasm for learning."

[No information in the chapter supports the latter claim, or suggests how enthusiasm would be measured or whether it is associated with actual learning.] "Cite an aspect of your development that differs from a parent's or grandparent's when he or she was your age. How might contexts explain this difference?" [Nothing in the question or the chapter directs the student to ways to measure aspects of development, or comments on effects of memory on the older person's presentation of his or her past. In fact, the student is not asked to get information from an older person. The first part of the assignment is irrelevant to the second, which basically asks for some contextual factors and effects they might (not do) have.]

"Find out if your parents read Gesell, Spock, or other parenting advice books when you were growing up. What questions... most concerned them? Do you think that today's parents have concerns that differ from those of your parents? Explain."

[Whether the parents read advice books is irrelevant to the questions that concerned them, so this aspect distracts from a critical approach ; the question does not guide the student to ways to find what concerns today's parents have, so he or she is asked to respond without sufficient supportive information; the student is unlikely to have an informed opinion on this point unless he or she is a parent, so the question further encourages uncritical thinking without sufficient information.]

"What aspect of behaviorism made it attractive to critics of psychoanalytic theory? How did Piaget's theory respond to a major limitation of behaviorism?"

[The student is asked to work with insufficient information. The text does not state that either assumption is true. In addition, to ask how Piaget's theory "responded" to an aspect of behaviorism suggests that the theory was shaped by shortcomings of behaviorism, which is not correct and tends to confuse the student's attempt to compare behaviorism and other theories. This language may simply be an ill-advised attempt to avoid saying "Compare and contrast".]

"Return to [the] table... which lists advantages and disadvantages of parenthood. Which are most important and which least important to you? What is your ideal family size?"

[Other than the use of the table, this question appeals only to the student's personal views and does not involve the weighing of evidence or other critical thinking skills. There is little connection between the question and information about development. In addition, neither the student nor the instructor can use a response to this question to determine whether the student understands relevant information or has given a considered answer.]

"[__], who is expecting her first child, recalls her own mother as cold and distant. [__] is worried about whether she will be effective at caring for her new baby. What factors during pregnancy are related to maternal behavior?"

[The details about [__] are irrelevant to the question, and potentially distract students into answering in terms of relationships they have experienced. In addition, the question cannot be answered on the basis of any information in the related chapter, which refers to maternal attitudes but not maternal behavior.]

"Which explanation of infants' cognitive competencies do you prefer, and why?"

[This question is couched in terms of personal preferences, not of evaluation of evidence or logic. A student who reads closely may be tempted to say "I like this one because the words are easier to spell", but most will simply search the text for the right answer.]

"Do you believe that teaching infants and toddlers to control the expression of negative emotion is very important? Explain."

[This question asks the student to state a personal value (very important), without explaining either the goal of the training, what it would mean for the training not to be very important, or whether control means suppression of emotion or regulation of modes of expression. Once again, the ambiguity of the question encourages an uncritical response.]

Finally, the frequency of emotional language in this book should be noted, as it encourages an uncritical approach by providing irrelevant details and distracting the student from the task at hand. The table of contents contains the following words: amazing, tragedy, mysterious tragedy,and powerful, none of which are necessary descriptions of the contents. Here is the caption under a picture of a toddler: " This boy has spent his first two years in a Romanian orphanage, with little adult contact and stimulation. The longer he remains in a barren environment, the more he will withdraw and wither and display permanent impairment in all domains of development." This vivid writing is no doubt engaging, but creates a barrier rather than a bridge between the illustration and available evidence concerning the later, non-withered, development of the Romanian orphans who have received such careful study.

Trouble with Instructors

Regrettably, it is all too easy for instructors to contribute to critical thinking problems by responses in the classroom or by assessment of essay assignments. For example, most instructors attempt to make their remarks vivid, memorable, and student-friendly by including dramatic events and descriptions of interesting but extraneous factors. Students do remember such information, and many instructors have found that answers to essay questions sometimes refer to "what you said about what your little boy did" or other personal details.

However, it has been demonstrated clearly that extraneous information, however attention-getting it may be, confuses critical thinking about the real issues ( Stanovich, 2004; Tversky & Kahneman, 1974; Waldrop, 1987). To omit those interesting details seems undesirable, as they do help establish memory for concepts; however, it may be a good idea to follow such examples by reminding students about individual differences.

Instructors often permit or provide plausible, unsupported explanations of developmental events, as indeed do developmental theorists. Discriminating between the plausible explanation and the explanation supported by evidence is one of the steps in developing reasoning capacities (Kuhn, 1993). Of course, recognizing that an argument is a plausible one is an important critical thinking skill, without which the formulation of hypotheses would be extremely time-consuming, if not impossible. But recognizing that an argument is only plausible is an essential advance, without which "confident speculation" is a likely response.

It is easy enough to remind students of the evidence that would be needed to support a plausible argument found in developmental science work. It is more difficult to respond to a student's offered plausible explanation in such a way that criticism is perceived to involve the nature of all plausible arguments, rather than the acceptable plausibility of this one. Instructors may find it quite difficult to avoid emphasizing confirmatory data over non-confirmatory, or permitting students to stress confirmatory data (Klaczynski & Narasimham, 1998).

Having asked students to participate by offering examples of the developmental phenomenon under discussion, and having received one or two appropriate examples, how many of us inquire, "how many people have had completely different experiences? " rather than simply thanking the students who have commented? Generally, instructors are happy if examples are relevant to the issue, and fail to concern themselves with the importance of counter-examples.

Instructors generally fail to give adequate attention to the examination of false statements. If a student has made the statement, the instructor politely turns to someone else for the answer, knowing that students are offended by any clear statement that they are wrong, or by any attempt to examine the reasoning behind the statement. (Even if the statement is correct, trying to explore the reasoning behind it often makes the respondent feel that he or she has made a mistake-- if it's right, it's right, and that's all there is to be said.) If a false statement has appeared in the textbook or come up in media presentations, instructors often ignore, ridicule, or dismiss it, rather than modeling for students the process of examining it thoroughly.

These practices play into the problematic tendency to stress what is true rather than what is false, thus creating problems in examining the consistency of a set of statements ( Johnson-Laird, Legrenzi, Girotto, & Legrenzi, 2000).

Critical Thinking Problems Related to Topics in Developmental Science

In this section, I will describe some specific problems of critical thinking-- incidents where many thinkers make systematic errors-- and their relevance to some topics and problems of developmental science. It is possible that correction of these types of errors can help students understand material that they otherwise find confusing. It is also possible that the modeling of these errors by lecture or textbook may limit students' ability to detect them. The types of errors discussed here were chosen from a list put together by Gula (2002), who did not use examples from child development.

Problems of Irrelevance

A major critical thinking issue for most students is their inability to discriminate between relevant and irrelevant information, and their tendency to be distracted or confused by irrelevancies. I would point out again that our well-intentioned efforts to make textbooks and lectures vivid and engaging, through the use of vignettes and illustrations, add to the amount of irrelevant and distracting information presented to students.

The argumentum ad hominem. Forms of argument that focus on personal characteristics of theorists and researchers are appealing to students, but distract attention from the theory or research itself. Weaknesses of the individual or of his or her work are used as ways to evaluate entire systems. For example, a discussion of economics on National Public Radio recently began with some of the less attractive personal characteristics of John Maynard Keynes, and one discussant expressed surprise that the country was turning to such a person for solution of its economic difficulties.

In discussions of developmental science, here are some similar situations, where an instructor might offer "gossip" as a way to get interest, and students might then reject the more important information:

• Piaget's observations of his own children are considered a reason to dismiss the entire theory of cognitive development.
• J.B. Watson's questionable treatment of little Albert, and his ill-judged advice about parenting, are seen as arguments against behaviorism.
• Kohlberg's suicide is taken to mean that his work on moral development is worthless.

The non sequitur. The presentation of conclusions that do not logically follow from evidence is distracting to student thought, but usually not recognized by students as causing any problem. An illustration caption in the textbook mentioned earlier reads: "...overstimulating babies with academic training and other lessons can impede brain development and the child's desire to learn" (the connection between brain development and the desire to learn being the non sequitur).

The Appeal to Irrelevant Authority

Irrelevance can be confounded with other factors, too.

The appeal to the past. Arguments that begin with references to past claims ("Freud said...", "Parents have long known..."), without presenting further evidence, are distracting and conceal their irrelevance to the cognitive task at hand.

Apriority and the appeal to personal belief or experience: Students like to hear personal stories from their instructors, and publishers certainly believe that vivid personal details add to the desirability of a textbook. However, the use of such details presents two problems: first, the distraction of general irrelevancy, and second, the suggestion that if one individual's experience is of a certain kind, all or many others have similar experiences, and the vividly described experience can be taken as typical of an entire population. In fact, however, an individual's experience may be quite atypical and therefore irrelevant to population characteristics.

More generally, the appeal to personal experience involves the problem of apriority, or the building of argument on unexamined a priori assumptions of various kinds.

Confident Speculation

It is a common error of critical thinking to present speculation as if it is reliable evidence that backs up a claim. This error is an easy one to make in teaching about developmental science, as many claims are based on complex research whose details are far beyond what can be handled in a first undergraduate class. In addition, the many aspects of developmental work that are value-laden -- for example, questions about physical punishment of children -- may have little or no actual evidence basis.

Personal assurances of certainty. Especially when discussing emotionally-laden topics, instructors are often driven to say, "Nobody really knows, but I'll tell you what I think, for what it's worth." Students may attend much more carefully to the personal assurance given in this statement than to the warnings of possible uncertainty that the instructor feels he or she has given. In cases where instructors use the classroom as a bully pulpit, of course, the impact of their assurances may be inappropriately great.

Appeal to personal experience. Because pedagogy for the last 40 years has stressed the need for students to make a personal connection with topics they are studying, most instructors and textbooks make a point of asking students to review their personal experiences. This was apparent in a number of the textbook quotations given earlier. In fact, however, the appeal to personal experience is a matter of confident speculation to the effect that the individual's experience is typical and representative of members of a group under study.

Oversimplification

Developmental science, and development itself, are complex and multifactorial, and in many cases involve nonlinear relationships. Teaching and writing for undergraduates requires us to abstract and simplify some complicated material. The danger in terms of critical thinking is that necessary simplification will become oversimplification, and that we will fail to correct oversimplification by students.

Posing complex questions that contain apriority. The textbook question quoted earlier, "Cite a difference between..." addresses complex issues of variability and its causes. However, it oversimplifies by implying that generational differences are larger than individual differences within a generation, an a priori assumption that may or may not be correct.

The excluded middle, or categorical thinking. It is an error of critical thinking to assume, without evidence, that an idea is either completely correct or completely incorrect, or that phenomena belong to clearly dichotomous categories. This type of error is common in textbook statements and questions ("Do you believe...?"), but historically speaking, it is also a characteristic of the study of development, with its long discussion of a dichotomized Nature vs. Nurture. The love of typology is one of the more problematic aspects of the study of development, although the existence of cases of three rather than two categories may obscure this issue.

For example, note the many decades of acceptance of categories of attachment security (Ainsworth, Blehar, Waters, & Wall, 1978), and the minor interest displayed in attempts to examine attachment phenomena in terms of continuous variables (Roisman, Fraley, & Belsky, 2007). Students for whom critical thinking is difficult may be drawn to categorical descriptions which require memorization of a short list of categories and provide easy applications to real-world events.

The fallacy of the beard. This problem of critical thinking has to do with the understanding of overlapping categories. If a person has no whiskers, he doesn't have a beard; if he has hundreds of whiskers, he does have a beard. If he has two whiskers, or three, he has no beard, but the addition of more whiskers will eventually mean that there is a beard. Problems of this kind challenge critical thinking abilities because they require systematic discrimination of evidence and the recognition that definitions may be arbitrary. For the weak critical thinker, it is much easier to assume that if the phenomena overlap, there is no difference between them, or that, if the overlap is small, there are no similarities between them. To avoid this kind of error, it is essential to work through and agree upon definitions of terms.

The beard error is especially problematic for the understanding of gender differences and other population differences, like those associated with culture. Even more importantly for the teaching of developmental science, the fallacy of the beard interferes with the understanding of developmentally appropriate practice. Students prone to this fallacy may confuse the characteristics of toddlers, preschoolers, school-age children, and adolescents as they group all these ages under the rubric "children". Alternatively, and even alternately, they may exaggerate differences between adolescents and people of other ages, blurring the resemblances between adolescents and younger children. Students who ask practical questions in class ("I know a boy who... what should I do?") rarely indicate the age of the child in question and must be asked before an answer can be given. Similarly, both students and parents tend to prefer preschool child care that resembles elementary school, and exaggerate the resemblances between older and younger children rather than the developmental differences.

The fallacy of determination. An oversimplified view of behavior concentrates on an individual's wish to carry out an action, claiming that if a person, particularly a child, wants to do something, he or she will do it, and that if he or she does not act, the reason is a lack of motivation. From this critical thinking error follows the assumption that behavioral or cognitive change results solely from the manipulation of motivation by means of reward or punishment. Such assumptions interfere with understanding of cognitive development and indeed of all development based on maturational change.

Analogies and Metaphors

Analogies and metaphors are useful thinking techniques that compare two different things by showing the ways in which they are similar. These techniques are helpful in teaching about development, as many developmental events are difficult to observe directly or occur over long periods of time. The problem with analogies and metaphors is that although they may be used to convey ideas, they cannot in themselves establish an argument or support an inference. To attempt to use them in that way is to risk the error called "abusing an analogy."

Common analogies. Here are some common analogies and metaphors used in the teaching of developmental science:

1) "stages" or "milestones" of development;

2) the term "attachment" or "bond" to describe an attitude toward another person;

3) brain/cortical/ hand/gene "dominance" (this metaphor may be one reason why it is so difficult for students to define dominant and recessive genes);

4) "regression" (not the statistical kind);

5) the term "sexual" in the description of psychosexual stages of development.

These comparisons may be extremely valuable for teaching purposes, but their downside is the student's assumption that phenomena that have some things in common will have everything in common.

Abusing analogies. As Gula (2002) has suggested, analogies are abused when the terms of one element are used (and assumed) to predict the terms of another element. In order to avoid such abuse, several steps in evaluation are needed.

1) The thinker needs to ask whether all the properties of X and Y -- the two elements or phenomena -- have been cited. Concentrating on similarities alone is potentially problematic.

2) The thinker needs to ask what proportion of the characteristics show similarities.

3) The thinker needs to ask what proportion of the similarities are actually relevant to the issue under study; for example, the fact that many mice and many human beings have brown eyes is irrelevant to the use of mouse developmental information to draw conclusions about human beings.

4) The thinker needs to ask to what extent X is actually different from Y -- that is, what proportion of the characteristics of the two are different.

No clear rule exists for accepting or rejecting an analogy on the basis of these questions, but questioning the analogy can help prevent misuse of this type of reasoning.

Easily abused analogies. In the study of development, one common instance of abuse of analogies involves reasoning from aspects of non-human development to aspects of human development. For example, John Bowlby's application of ethological concepts of imprinting in birds to human attachment abused an analogy, and was fortunately rejected after some consideration by developmental scientists. But this type of critical thinking error is still with us, and not in textbooks alone.

For example, a recent article in the APA Monitor on Psychology (Price, 2009), entitled "Programmed for life?" has a subhead stating that "Your developmental environment can undercut your memory, give it a boost, or possibly even predict how you'll treat your children." Examining this article, one sees that the only information relevant to "how you'll treat your children" is a study of factors influencing how much mice lick and groom their pups. A comparison of the characteristics of mouse and human infant care suggests that this author has abused an analogy in order to conclude that the factors being discussed "may" predict how humans will treat their children.

A bad example: Attachment as a "tie". A particularly questionable use of analogy occurs when a comparison is presented as if it were a definition. For example, many textbooks and other sources define attachment as "an emotional tie between parent and child." In fact, attachment is only somewhat comparable to a tie of a physical nature. It keeps the individuals close together, but being tied is different from attachment in that attachment changes with age, is not directly measurable but is implied by behavior, and influences the two partners differently. If the tie in question is a social relationship rather than a physical tie (using an analogy to create another analogy), the definition and the comparison become circular, and the only meaningful part of the definition is "between parent and child"; even this is deceptive, as it implies that the emotions of parent and child are similar, which they are not.

Affirming the Consequent and Other Forms of Transductive Reasoning

Piaget's discussion of preoperational cognition included a description of transductive reasoning, a form of primitive logic in which a child assumes that when two events share some characteristics, they are likely to share others, including a cause-and-effect relationship which may work in either direction.

Piaget's famous example of this was a situation in which his daughter, given a cup of orange-colored chamomile tea, insisted that a green orange she wanted must have become ripe and attained the color that meant she could eat it. Similar examples involve the wind being made to blow by trees waving their branches, and fire engines causing ("putting out") fires. The adult version is the belief that correlated events are causally related. Other specific forms of this error may be highly relevant to the teaching of developmental science.

Affirming the consequent: This fallacy or error in critical thinking involves the practice of assuming that the converse, or reverse order, of a claimed condition is true. For example, let's take the statement that

If a child has Reactive Attachment Disorder, she has lived in an orphanage or under similar conditions. [This is true, as the DSM list of criteria for the RAD diagnosis includes the etiology.]

The converse of this statement is the following:

If a child has lived in an orphanage (or under similar conditions), she has Reactive Attachment Disorder. [This claim is available to students on a number of Internet sites.]

To assume that this converse statement is true without requiring other evidence is to affirm the consequent.

Similarly, here is a correct claim:

Children who are developing normally have gone through many repetitions of infant reflex movements.

The converse of this statement is the following:

Children who have gone through many repetitions of infant reflex movements develop normally. [Affirmation of the consequent in this case argues support for the CAM treatment "patterning".]

Denying the antecedent. This critical thinking error involves the assumption that if a positively-stated claim is true, a negative statement (the obverse) can also be assumed to be true, without further evidence. For an example, here is a common (although questionable) claim:

If a toddler carries a blanket around, it means he feels insecure without it.

Here is the obverse of the claim:

A toddler does not feel insecure [without a blanket], if he does not carry a blanket around.

The problem, once again, is in the assumption that manipulating the words of the claim permits an accurate conclusion, whereas in fact additional evidence would be needed to support the obverse statement. In its present form, the statement suggests that insecurity can be cured by taking away a toddler's blanket, and this view is sometimes taken by students.

References