Encountering Counterintuitive Ideas
Encountering Counterintuitive Ideas
Constructing a Developmental Learning Progression for Evolution Understanding
Abstract and Keywords
This chapter provides evidence for a developmental learning progression, which can bridge the gap between everyday intuition and scientific reasoning about evolutionary change. First, it describes the learning principles that motivate a developmental learning progression and how they differ from those found in the learning progressions constructed by researchers working in formal education. The chapter then focuses on a developmental learning progression for biological evolution and details how children's and adults' intuitive theories about the natural world constrain their understanding of evolutionary theory, rendering it counterintuitive. The chapter then applies the proposed learning principles to children's and adults' emerging grasp of evolutionary theory and describe both age-related changes in children's and adults' reasoning and changes in reasoning following visits to informal science exhibits on evolution.
“Children's rich but naïve understandings of the natural world can be built on to develop their understanding of scientific concepts”
—(Duschl, Schweingruber, & Shouse, 2007, p. 3).
Studies of human encounters with counterintuitive ideas offer revealing insights into the workings of the human mind. This volume provides examples of such insights gained from investigations of the rejection and misunderstanding of Darwinian evolutionary theory. Along with several other authors in this section (Coley & Muratore, this volume; Gelman & Rhodes, this volume; Kelemen this volume; Shtulman & Calabi, this volume), we argue that Darwinian evolutionary theory radically challenges an everyday understanding of the world, as stable, purposeful, and designed. In contrast, creationist beliefs appear to be more easily reconciled with these everyday intuitions (Evans, 2000a, 2001, 2008). Human evolution, in particular, challenges the intuition that humans are both privileged and destined to escape the fate of most other species on this planet (Evans, 2000b, 2001; Poling & Evans, 2004). About half of the adult population in the United States endorses some form of creationism, and even those who endorse evolution are likely to harbor substantial misunderstandings (Evans et al., 2010). Why is this the case?
The fundamental argument advanced here is that this is, in part, a consequence of the foundational theories that young children use to interpret their world, which constitute the basis on which much future knowledge acquisition is built (Wellman & Gelman, 1998). One of the earliest and most well studied of these (p.175) is children's “theory of mind,”—children's understanding of mental states (e.g., beliefs and desires) and behaviors that may result from those states (Wellman, 2011a; Wellman & Gelman, 1998). We claim that the power of this theory leads, even by the early elementary school years, to its overextension and application in unwarranted circumstances. In this case, a theory of mind contributes to an anthropomorphic, artificialist explanation for the origins of species. Regardless of their parents’ religious beliefs, 8- or 9-year-old children (in the United States at least) are likely to endorse creationist explanations (“God made it”) for the origins of species. Children seemingly draw on their intuitive artificialism (“someone made them”) (Piaget, 1929) and describe species as artifacts created by the hand of God (Evans, 2000b 2001; Kelemen, 2004, this volume).
Cultural context, though, clearly exerts powerful, as well as more subtle effects. By early adolescence, children raised in more religious contexts, such as Christian fundamentalist homes and schools, are more likely to maintain and extend their creationist ideas, whereas their nonfundamentalist counterparts are more likely to endorse evolutionary views of the origin of animals, including common ancestry (Darwin's theory of descent with modification). Importantly, this endorsement of evolution is related to several factors that potentially challenge the preconceived notion of a stable world with humans at its center: exposure to the fossil evidence, a grasp of metamorphosis, and agreement that humans are animals (Evans, 2008). Endorsement of evolution is also stronger among those who accept the (incorrect) idea that animals change in response to environmental factors, called need-based reasoning (e.g., reasoning that giraffes’ long necks result from their habit of stretching their necks to reach into tall trees to obtain food) (Evans, 2001). In contrast, children from fundamentalist homes are more likely to believe that God is responsible for changes in an animal population (e.g., God builds the potential for diversity into their genes) and that humans are not animals (Evans, 2008).
How do such perspectives develop? The critical process, we claim, is the interaction between the intuitive ideas that children generate to explain natural phenomena and an environment that serves to reinforce, transform, or suppress such ideas. Children play a role in this process by selectively assimilating compatible ideas and ignoring or rejecting certain ideas that are less well attuned to their intuitive frameworks. In fundamentalist homes, the idea of God as an all-powerful creator is pervasive, eliciting anthropomorphic reasoning that both undermines naturalistic explanations of change and reinforces the notion of a designed and stable world (e.g., “God made it that way, so it can't change,” Evans, 2001). In contrast, in nonfundamentalist homes children are more likely to be exposed to the evidence for biological change. Such exposure is associated with greater acceptance of the idea of evolutionary change. However, like most of their parents and many adults in other industrialized countries, these children do not grasp that natural selection is a key mechanism of evolutionary change; instead they resort to need-based reasoning—animals change because they need to adapt to the environment (Abrahams-Silver & Kisiel, 2008; Evans, 2001; 2008; Evans et al., 2010).
(p.176) In sum, regardless of belief system (scientific or religious), our claim is that human reasoning is mediated by a set of intuitive theories, which reduce information overload, making it possible to rapidly process information about the world. In addition to a theory of mind, discussed above, researchers have suggested that intuitive biological and physical/mechanical theories serve to help children and adults reason about living things and inanimate objects. These intuitive theories help to constrain and shape the reasoning of a young learner, who is constantly faced with an abundance of new information (Wellman & Gelman, 1998). There is a cost, however, as these constraints, such as the psychological essentialism discussed in a number of the other chapters (see Coley & Muratore, this volume; Gelman & Rhodes, this volume; Shtulman & Calabi, this volume), also make it difficult to grasp counterintuitive concepts, such as biological evolution. The challenge, for educators striving to teach children and adults about evolution, is to determine how to confront these early constraints so that the human mind can contemplate certain counterintuitive ideas.
In this chapter we attempt to resolve this paradox by outlining those components of a developmental learning progression that could bridge the gap between everyday intuitions and scientific reasoning about evolutionary change. We begin by describing how learning progressions are currently conceptualized and consider what a developmental component could add to this conceptualization. We then apply the proposed learning principles to children's and adults’ emerging grasp of evolutionary theory and describe changes in children's and adults’ reasoning over time and after visits to museum exhibits on evolution. We conclude by briefly outlining the implications for science education more broadly.
Learning Progressions: What Are They?
Recent panel discussions at the National Academy of Science centered on the need for revamping the science standards and focusing on the core ideas in science (National Research Council, August 2009). The reasons for the proposed changes included the confusing proliferation of disconnected topics in the current standards and curricula that fail to build from one grade to the next in a coherent and integrated fashion (Duschl et al, 2007, chap. 8). Two directives, of relevance to this chapter, emerged from the NAS discussion (Eberle, 2009): (1) evolution and the history of life are core ideas, central to a contemporary grasp of biology; and (2) to construct a coherent set of standards, it is necessary to construct a learning progression (LP) for each core idea. At their simplest, learning progressions can be thought of as a set of successively more sophisticated ideas about a topic (Smith, Wiser, Anderson, & Krajcik, 2006). The crucial issue is that these ideas are constructed on the basis of children's earliest conceptions of the world, and each step in the progression is constrained by prior conceptions. Anchoring the other end of the progression is the expectation of the kinds of knowledge that an educated citizen should possess about the topic.
In addition to anchor points, current approaches to learning progressions incorporate inquiry-based learning practices, which encourage students to ask the kinds (p.177) of questions that lead to an understanding of material that is specific to particular content areas. Importantly, because learning progressions have been based primarily on studies of students’ learning in formal contexts, a defining characteristic is that the learning occurs in the presence of specific instructional practices (Duncan & Hmelo-Silver, 2009). This is not the spontaneous mostly untutored learning more likely to be found in informal learning contexts, such as the home or a museum. The scaffolding of children's understanding through systematic and repeated exposure to increasingly complex material also defines the spiral curriculum proposed by Bruner and colleagues (e.g., Bruner, 1996). Learning progressions are the most recent manifestation of this approach. Next, we provide more details of this approach by describing some prototypical learning progressions and later we expand this description to include a developmental component, which could be applied to both formal and informal learning experiences, where spontaneous learning is more likely to occur.
Although the science education community seems to be in agreement that learning progressions potentially provide an important framework for promoting students’ understanding of core ideas in science, there is a lack of consensus on what exactly constitutes a learning progression (Stevens, Delgado, & Krajcik, 2010). From a conceptual change perspective (see Sinatra, Brem, & Evans, 2008), part of the problem is that existing approaches to learning progressions appear to be atheoretical, in that there seem to be few unifying learning principles guiding the research. For the most part, the current research on learning progressions and the actual progressions developed from this research are both informed by and constrained by an analysis of curricula demands. For example, the national standards for each grade level describe each set of core ideas that characterize a particular domain, these, in turn, serve as a very strong constraint on both research and practice with respect to learning progressions. Catley, Lehrer, and Reiser's (2005) seminal proposal for a learning progression for evolution in K–12 school science is an example of this top-down approach. It is largely based on core concepts, such as those articulated in the standards documents of the American Association for the Advancement of Science (AAAS) and the National Research Council (NRC), though they have tightly connected these concepts to specific inquiry-based practices. However, even these researchers find that the learning progressions that they describe are incomplete and should be viewed as signposts, pointing the way to future research. In particular, as repeatedly emphasized by Duschl, Schweingruber, and Shouse (2007), they do not make explicit the connections to the kinds of knowledge that students bring to the classroom.
Learning Progressions: Examples
Several learning progression proposals have been derived from extensive empirical studies of students’ understanding of particular concepts within a curriculum as assessed in cross-sectional studies. Stevens and colleagues, for example, present (p.178) a learning progression in which they map out middle- and high-school students’ developing understanding of the nature of matter (Stevens, Delgado, & Krajcik, 2010). This particular progression is described as hypothetical because it cannot characterize all students’ trajectories, in that learning is not necessarily a linear process and is influenced by multiple factors. Like other learning progressions, each level is thought to be qualitatively different from the others. In this case, the uppermost level or anchor is described as a richly conceptualized set of integrated core ideas. At the lowest level or anchor are more impoverished ideas and isolated pieces of knowledge. This particular progression was created from iterative empirical research with middle- and high-school students, earlier research with elementary school students, as well as an extensive analysis of the standards and the relevant instructional materials. A crucial feature of this approach is the emphasis on progressively interconnected core ideas. This approach is consistent with diSessa's characterization of the novice learners’ knowledge as comprised of isolated incoherent ideas—knowledge in pieces—with the expert having a more coherent and interconnected representation of the domain (diSessa, 2008). In this respect their proposal is similar to that of Catley, Lehrer, and Reiser's (2005) proposal, as the latter also note that a synthesis of “big ideas” is key to a more sophisticated understanding within a particular domain. The broader implications of this body of work is that a sound grasp of a limited number of significant ideas and how they are interconnected provides the foundation for advancing knowledge in any domain. Too much detail, however, may impede the progression to a deeper understanding of a domain (Stevens, Delgado, & Krajcik, 2010).
Other empirically based approaches to learning progressions include longitudinal studies of students’ reasoning as they encounter targeted learning experiences. An example of this approach is a learning progression devised by Songer and colleagues (Songer, Kelcey, & Gotwals, 2009) that focuses on upper elementary school students’ reasoning about biodiversity. In their studies, a student who reasons more effectively coordinates scientific claims and evidence to build a systematic explanation of why, for example, a particular animal may (or may not) be an insect. They developed this progression in a five-step sequence, from the initial articulation of the core ideas that must be acquired, to a 3-year curricular-based learning progression that articulates the interconnection of these core ideas. For these researchers, a learning progression should be generative in that it provides a template for both curricular and assessment products. The evaluation of the learning progression itself is carried out indirectly via these curricula and assessment products. As with many learning progressions, this particular one was initially based on an extensive analysis of what students should know, a top-down approach. The progression was then extensively revised in an iterative process that included repeated analyses of student explanations. In this manner, Songer and colleagues offer a detailed model for the development of an effective learning progression that directly informs the improvement of assessment and curricular products for formal learning experiences.
(p.179) Consistent with a developmental perspective, Songer and colleagues’ progression emphasizes students’ explanations and the integration of content knowledge with explanations, rather than the acquisition of facts. Recent work in developmental psychology has also focused on children's explanations and the kinds of parent-child interactions that promote explanatory competence (e.g., Frazier, Gelman, & Wellman, 2009; Tare et al., 2011; Wellman, 2011b). A child's explanations and how such explanations change with development and instruction should serve as the foundation of learning progressions because they provide the building blocks of future knowledge acquisition, in any domain. In the following sections, we clarify how these links between children's explanations and learning progressions might be effectively made.
Learning progressions, such as those summarized here, whose inception originated with curricular demands, provide the basis for novel curricula or assessments that could be used to improve student outcomes. So far, however, they do not seem to be based on more general principles of learning. Current learning progressions also do not provide information about the factors that might jump-start a particular progression. What is needed is a bottom-up approach—an analysis of a domain that begins with “children's rich but naïve understandings of the natural world,” which complements the top-down curricula driven approach (Duschl, Schweingruber, & Shouse, 2007, p. 3). Although some researchers, such as Stevens, Delgado, and Krajcik (2010), do begin their progressions with analyses of younger students’ ideas, it is unclear how the earlier analyses influence their learning progression.
One exception to this top-down approach is a recent description of a learning progression for celestial motion. Children's initial grasp of this domain, like that of evolution, is based on their everyday observations of the world, which is at odds with the scientist's worldview (Vosniadou & Brewer, 1992). To the everyday observer, the sun apparently rises and sets each day; but to the scientist these “observable celestial phenomena can be explained through the unobservable motions of the earth and moon” (Plummer & Krajcik, 2010, p. 768). Plummer and Krajick ground the beginning of their progression in analyses of students’ early ideas. However, the overall learning progression is framed by the logic of the discipline and specific curricular experiences. Nevertheless, this is one example of researchers using the complementary approach that we are advocating. Next we consider how the addition of a developmental framework to the kind of analysis carried out by Plummer and Krajcik could be used to build a learning progression for evolution.
Developmental Learning Progressions: What Can They Add?
Proposed Learning Principles
Developmental psychologists, from Piaget onward, have documented successive age-related changes in children's reasoning about the world. While Piaget focused on domain-general changes in children's reasoning, his successors have generally (p.180) focused on changes in children's intuitive reasoning within more specific domains, such as an intuitive biology, physics, or psychology (e.g., Carey, 1985; Inagaki & Hatano, 2002; Wellman & Gelman 1998). Developmental psychologists have taken a mostly bottom-up approach to understanding how children's reasoning becomes more sophisticated within particular domains; this is the kind of reasoning that occurs in informal settings. In contrast, and as just described, researchers constructing learning progressions have taken a more top-down approach, by creating progressions that focus on specific curricula and assessment products. Though some researchers using this approach may consider the past history of the learner (Duncan & Hmelo-Silver, 2009; Songer, Kelcey, & Gotwals, 2009), in general there is not much consideration of children's initial explanations of the domain and how these change over time, with the Plummer and Krajcik (2010) study being a notable exception.
In the rest of this chapter, we combine these two approaches and create a complementary synthesis that we call developmental learning progressions. We highlight this approach with a focus on two key core ideas relevant to understanding evolution: common descent and natural selection. Moreover, this approach focuses more on the spontaneous learning that occurs in out-of-school or informal learning contexts, including the home. We ask: What are the big ideas about evolution that members of the public find most counterintuitive and what are the early precursors of these big ideas? This approach is not based on what children ought to know at each age or educational level as defined by the curricula standards and the current logic of the discipline. Rather, we ask what it is children of a certain age do know and how this knowledge unfolds as children are exposed to ideas about biological change at home and in school. By tracing the early development of these ideas, we hope to uncover the stepping-stones that pave the way to an understanding of evolution. At the same time this type of analysis should, in turn, inform the kind of learning experiences that are most likely to help the learner traverse those steps. Finally, we provide evidence that relatively brief informal learning experiences can foster this learning progression if those experiences target particular early intuitions that must be addressed in order to advance understanding. We characterize this as a developmental learning progression (DLP) because it is a (largely) bottom-up approach that embodies the following principles:
1. Conceptual change is brought about by building on children's existing framework explanations for a particular core idea; the bottom anchor of the developmental learning progression is initially defined by these conceptions.
2. The upper anchor is defined by the kinds of concepts that are relatively robust representations of the scientific consensus for the domain in question. These representations may lack factual detail, but contain the core ideas that a well-educated and informed nonexpert (in that domain) might retain after the formal educational experience is concluded.
3. New understandings emerge from the interaction of different types of constraints. Although constraints are often thought of as factors that limit (p.181) thought and behavior, we suggest that they also can guide or facilitate learning.
4. Dual process theory provides one means of understanding this learning process. Cognitive biases or constraints operate at the intuitive-autonomous level (System 1 processing), some of which, we argue, potentially anchor evolutionary and creationist ideas. At the other end of the continuum, reflective and abstract reasoning (System 2 processing) is apparent in both scientific and theological explanations of origins.
5. The persistence of robust “misconceptions” is evidence of their functionality. These conceptions arise from System 1 processing, which are adaptive in many common everyday situations and are expressions of the intuitive theories that frame children's (and adults’) understanding of the natural world.
6. Earlier or alternative explanations are not discarded, as new explanations are elaborated. Recent work has focused on hybrid or mixed explanations, in which intuitive and/or apparently contradictory explanations coexist with the newly elaborated scientific explanation; for example, creationist and evolutionist explanations are often used in a complementary fashion to explain the same or related phenomena (Evans & Lane, 2011). Synthetic explanations (Vosniadou, Vamvakoussi, & Skopeliti, 2008), in which intuitive and scientific constructs are integrated, are commonplace.
7. As learning takes place, children's prior conceptions become integrated into an emerging conceptual structure in which novel explanations are used to make connections between previously unrelated conceptions. However, different domains may be characterized by different modes of conceptual change.
Applying a Developmental Approach
As our starting point, we take current research in developmental psychology (see Coley & Muratore, this volume; Gelman & Rhodes, this volume; Kelemen, this volume; Shtulman & Calabi, this volume) and the cognitive and learning sciences (see Catley, Novick, & Funk, this volume; Chi, Kristensen & Roscoe, this volume; Matuk & Uttal, this volume) as well as our earlier studies (e.g., Evans, 2000a, 2001) to establish the lower anchors of a developmental learning progression for evolution. We then focus on the transitional points in an understanding of common descent and natural selection. In effect, we are asking the question: If we take a bottom-up approach, what would a learning progression look like? Instead of treating these basic intuitions described in the earlier chapters as misconceptions that must be eliminated, we see them as part of a systematic body of ideas that constrain children's understanding. For successful learning to occur, these should be incorporated into a learning progression that eventually yields or is responsive to the core ideas in science. In this respect we differ markedly from the approach to (p.182) learning progressions described earlier, in which children's early knowledge is often seen as impoverished.
Although we agree with researchers such as Catley, Lehrer, and Reiser (2005) and Stevens, Delgado, and Krajcik (2010) that a mark of successful learning is the integration of several core ideas into a cohesive framework, we consider children's earliest knowledge as “locally” coherent rather than fragmented (diSessa, 2008; Evans, 2008; Evans et al., 2010; Vosniadou, Vamvakoussi, & Skopeliti, 2008). Even when adults and children combine explanations from seemingly incompatible domains, such as the supernatural and the natural, to explain a single phenomenon, that explanation is often locally coherent. For example, some theologians and evolutionary biologists argue that while evolutionary theory explains the origin of species this still leaves open a role for a supernatural being as the ultimate cause of the natural world (Evans et al., 2010; Evans, Legare, & Rosengren, 2011; Miller, 1999). We are not making claims that nonscientists, at least, can provide much in the way of explanatory depth for any phenomenon. In fact, Keil and Wilson have convincingly demonstrated otherwise (see Keil, 2010; Keil & Wilson, 2000; Wilson & Keil, 1988). Rather, we are confining our claim to the idea that children's and adults’ intuitive explanatory frameworks work for them, most of the time, though more detailed evidence necessary to support such a claim is beyond the scope of this chapter (see DiSessa, Gillespie, & Esterly, 2004, for a review of the issues).
With some notable exceptions (Carey, 1985; Inagaki & Hatano, 2002; Vosniadou, Vamvakoussi, & Skopeliti, 2008; Wiser & Smith, 2009), work done in developmental and cognitive psychology on domain-specific learning has tended to be piecemeal and not tied to core ideas in science. Here we apply the concept of a developmental learning progression to a core idea in science education with a focus on the development of children's earliest conceptions across a span of years. Although we use age-ranges as markers for the sequential acquisition of these ideas, we conceive of this sequence as the acquisition of knowledge structures, with more intuitive structures providing the stepping-stones (Wiser & Smith, 2009) to more sophisticated ones. Age is only a proxy for children's level of cognitive development, neurophysiological development, and the quality of their everyday experiences with the world. Crucially, this is not a replacement model of conceptual change. Instead, as children experience a world of rich cultural conceptions, their foundational intuitions about the natural world are transformed and integrated into a sequence of transitional conceptions, each of which is functional in its own right. These conceptions correspond to qualitatively different levels or steps of a learning progression. Of course, children's ideas do not proceed in a lock-step manner. Developmental phenomena are more accurately characterized by considerable variability and heterogeneity (Rosengren, 2002; Rosengren & Braswell, 2001; Siegler, 1996). However, for children from any particular age group raised in a similar cultural context it would be reasonable to expect that the majority would share a particular construct.
The developmental learning progression for evolution understanding that we are proposing is not yet fully developed, but based on the research presented in the (p.183) chapters in this volume and our own research we feel we have enough evidence to put forward a proposal that encompasses some of the steps and enables us to make suggestions about what further research needs to be done to fill in the gaps.
Constructing a Developmental Learning Progression for Evolution Understanding
In what follows, we take each of the main principles summarized earlier and apply them to children's and adults’ emerging grasp of evolutionary theory. This serves to illustrate our general approach with a demonstration of how these principles could be used to specify a developmental learning progression for evolution, the central explanatory construct in biology.
Principles 1–2: Establishing the Anchors
1. Lower Anchors: Children's Explanations
Studies of children's intuitive psychology are key to an initial grasp of evolutionary change, not only because they model a way to assess a developmental sequence in a core domain, but also because an intuitive psychology provides an explanatory framework—an anthropomorphic framework—that children and adults can access easily and which they often use to explain biological processes (Carey, 1985; Evans, 2000a, 2001; Inagaki & Hatano, 2002). Moreover, work on young children's intuitive psychology provides insights into the kinds of locally coherent conceptions that young children have available to them.
The interpretation of human actions in terms of mental states, such as beliefs, desires, and emotions, is termed a “theory of mind,” and it is a core construct in the early development of an intuitive psychology (Wellman, 2011a). During the preschool years, children the world over acquire a robust early understanding of the mind, including an understanding that mental states are representational—that is, they do not directly reflect the reality of the world (Wellman, Cross, & Watson, 2001). Using a multimethod approach, Wellman and his colleagues have constructed a developmental scale that assesses five core constructs underlying children's earliest theories of mind (Wellman & Liu, 2004). In brief, this scale demonstrates that an understanding of desire emerges before the other constructs, followed by an understanding of knowledge-ignorance and diverse beliefs, then false belief, with an understanding of the distinction between real and apparent emotion emerging at around 6 years of age. Moreover, they have demonstrated that these constructs emerge in a sequential manner, such that children who grasp construct 4 in the sequence also grasp the first three constructs (Wellman, Fang, & Peterson, 2011). This is a nice example of a developmental scale that could be used as a model for constructing the initial aspects of a developmental learning progression, though it lacks an upper anchor that represents the current science of the discipline.
(p.184) Along with an intuitive psychology, an intuitive biology is also used to frame an early understanding of biological change (Atran, 1990; Evans, 2000b; Poling & Evans, 2002; Medin & Atran 2004), although the details of this foundational framework are not as carefully specified. The current consensus is that children and adults access several explanatory frameworks, shifting between them depending on the framing of the question (task constraint) and their level of understanding (organismic constraint) in each domain (Wellman & Gelman, 1998). Such causal flexibility (Poling & Evans, 2002), driven in part by different interactions of constraints, potentially provides greater explanatory depth, as various levels and kinds of explanations can be integrated to provide a richer interpretation of a phenomenon than can be obtained with a single cause (Evans, Legare, & Rosengren, 2011; Evans & Lane, 2011).
Researchers studying an everyday or commonsense understanding of the biological world suggest that it comprises two main elements: (1) an essentialist belief in the stability and the “true” underlying nature of biological kinds (Atran, 1990; Medin & Atran, 2004; see Coley & Muratore, this volume; Gelman & Rhodes, this volume; Shtulman & Calabi, this volume), and (2) a belief in the inherent functionality or purpose of nature—a teleological perspective (Kelemen, this volume; Shtulman & Calabi, this volume). Basic research studies focusing on how essentialism and teleological reasoning function in children's and adults’ thinking about the natural world have been discussed in detail in earlier chapters and elsewhere (Atran 1990; see Evans, 2008, for a summary); later, we describe how these reasoning biases provide initial stepping-stones that may pave the path toward evolutionary thinking. However, the paradox alluded to earlier remains: these constraints also make evolutionary thinking counterintuitive. How can they do both jobs? Only by tracing the intermediate steps between the earliest intuitive concepts and their descendents can one begin to make sense of this paradox. First, though, we clarify the upper anchors of this DLP, those evolutionary principles which, if understood, would provide a very basic grasp of evolutionary theory.
2. Upper Anchors: Common Descent and Natural Selection
In contrast to the construction of developmental scales, we look to the science of the discipline to establish the upper anchors of a developmental learning progression. However, as a DLP is not tied to a particular curriculum or to specific instructional practices but to the kinds of knowledge that the informed nonscientist might be expected to possess, this is not necessarily a straightforward task. Still, by taking advantage of a recent refocus of the national science standards on core ideas in science (National Research Council, 2009), we can clearly identify common ancestry/descent and natural selection as two core concepts in evolutionary biology, with evolutionary theory being one of the major concepts in biology (see National Research Council, in press).
As for the public understanding of evolution, results from Gallup polls (e.g., Gallup, 2007) over the past 20 years or so have been remarkably consistent, finding that about 50% of adults routinely endorse creationist beliefs for human origins (p.185) (i.e., God created them). Further, of those adults who do endorse evolution, the majority misunderstand the mechanism of evolutionary change—natural selection (Evans, 2008, Evans et al., 2010). It might seem obvious that once students understand natural selection, then they will also accept the concept of common ancestry, the fundamental evolutionary principle of descent with modification. But the evidence suggests otherwise; indeed a synthesis of these two core ideas is as difficult to achieve in contemporary populations, as was true historically (Evans et al., 2010). Only about a third of adult visitors to natural history museums exhibited a reasonable grasp of either construct, and even among this group of informed (rather than expert or novice) visitors, it was rare to find a visitor who articulated both constructs in a coherent framework (Evans et al., 2010; Diamond, Evans, & Spiegel, this volume; Macfadden et al., 2007). It should be noted that not only is a typical museum visitor interested enough in natural history to visit such a museum, the majority are also college-educated (Evans et al., 2010; Diamond et al., this volume). Thus neither lack of interest nor lack of exposure to the relevant material is a sufficient explanation of these findings.
Not surprisingly, studies of students’ grasp of evolution also demonstrated a disconnect between these core ideas. Early adolescents from nonfundamentalist communities often accepted common descent, the idea that modern animals descended from ancestral organisms that were quite different. Yet, they rarely grasped the mechanism of natural selection, the idea that changes occur at the population level, with those animals that were better adapted to a particular niche more likely to survive and reproduce (Evans, 2001). Rather, these early adolescents typically use need-based reasoning to explain evolutionary change—animals needed to change to adapt to a new environment. Children from Christian fundamentalist families who attended fundamentalist schools, in contrast, are very unlikely to accept common descent at any age (Evans, 2000a, 2000b, 2001); they are more likely to state that “God made them.” Even contemporary creationists who reject the idea of common descent (as they believe that God created each species with an unyielding essential nature) treat these phenomena as separate issues, not one. These individuals often accept the idea of natural selection providing it is used to explain within-species change in nonhuman animals, and not the origin of species (Evans, 2008; Evans et al., 2010). Thus these findings suggest that not only are these core constructs difficult to grasp, they are also difficult to integrate, or individuals may resist their integration. Based on this evidence, we will propose separate developmental learning progressions for the evolutionary principles of common descent and natural selection, with different constraints operating on each core idea (Evans, 2008).
Principle 3: Constraints on Learning
A key principle for a developmental learning progression is the idea that learning is facilitated when it is constrained. Implicitly, most learning theories acknowledge this construct, but here we formalize it: Learning is guided by the interaction of (p.186) constraints that operate at the level of the child (organismic constraints), at the level of the particular concept or task that confronts the child (task constraints), and at the level of the environment or culture in which the child lives (environmental constraints). For example, providing a child with a highly constrained task may serve to facilitate learning by limiting the number of possible alternatives that the child needs to consider when reasoning about the task. The theoretical basis for this view of learning is developed further in Rosengren and Evans's commentary (this volume; see also Rosengren, Savelsberg, & van der Kamp, 2003). In this chapter we focus on the effects of organismic constraints. These are characteristics of the human mind, such as intuitive theories, which facilitate learning by restricting the problem space, in particular by restricting the way data are conceptualized. We shall argue that a developmental learning progression arises because of the effects of constraints on each step or level of the progression.
I. Organismic constraints: Essentialism, teleology, anthropomorphism
Organismic constraints are those cognitive biases that arise from the intuitive explanatory frameworks structuring young children's understanding of the world around them. Such constraints narrow the focus of attention, allowing the child to derive the maximum information from a potentially chaotic environmental input. The organismic constraints identified in young children's and adults’ reasoning about biological kinds provide the means to both facilitate and/or inhibit their grasp of evolution. The essentialism of an intuitive biology both undergirds and undercuts an evolutionary biology (Evans, 2001). Essentialism undergirds it by “getting biological thinking off the ground” (Gelman & Rhodes, this volume); it undercuts it with a focus on the ideal type, the essentialist construal of species. Furthermore, a focus on the ideal type directs attention away from the variability inherent in any biological species (see Coley & Muratore, this volume; Shtulman & Calabi this volume; Shtulman, 2006). Instead of seeing variability as potentially functional, providing the means for survival in a novel environment, it is seen as superficial (Evans, 2000; Evans et al., 2010) or is ignored. How does essentialism help? Not only does a belief in an “essence” provide an intuitive principle for grouping animals into “kinds,” it also provides a cognitive tool for creating classes and hierarchies of biological entities (Coley & Muratore, this volume), which serve as the basis of our taxonomic system of classification. But a taxonomic system derived from a folk biology, such as the Linnaean hierarchy (see Atran, 1990), is founded on the similarity of unchanging “types,” rather than common ancestry; it is the latter construct that gives us the answer as to why species might be related (Catley et al., this volume).
One reason, we argue, for the failure or refusal to integrate common descent and natural selection is that each principle challenges different components of the everyday essentialist intuition (Mayr, 1982) that serves to constrain an understanding of evolution. Common descent challenges the idea that each kind of animal is possessed of a unique unchanging essence. This essentialist view of “species” is (p.187) incompatible with the perspective that one kind of animal could be the ancestor or descendent of a completely different kind, because a “species” cannot change without destroying its essential identity. Such essentialist views are found among young children (Coley & Muratore, this volume; Evans, 2000, 2001; Gelman, 2003; Gelman & Rhodes, this volume; Shtulman & Calabi, this volume) and are also enshrined in the Bible, which provides theological backing for Christian fundamentalists’ rejection of common descent (Evans, 2008). A second component of an essentialist view is that differences between members of a species are seen as largely superficial, which makes it difficult to grasp the mechanism of natural selection; sensitivity to the consequences of within-species variability is necessary to grasp that mechanism.
In sum, the acceptance or rejection of common descent is largely (but not only) driven by essentialist beliefs in the fundamental differences between kinds of animals, which is reinforced by religious belief, with fundamentalists (of most religions) most likely to reject it (Evans, 2000, 2001). While nonfundamentalists often accept the idea of common descent, they are very likely to misunderstand the mechanism of change. Regardless of religious belief, an understanding of natural selection seems to be problematic for adults and children alike, even for adults in countries that do not embrace creationist ideas (Abraham-Silver & Kisiel, 2008).
Teleological concepts have long been cited as the stumbling block for evolutionary thinking (Mayr, 1982). They provide purpose, where there is none (Evans, 2000a; Kelemen, this volume). Certainly, if purposeful thinking is tied to an extrinsic goal, specifically the intentional goal of a supernatural designer, then it may well be an impediment. Further, if within-species change is described in intentional terms, as if the animal makes a conscious decision to change—“the bird wanted a bigger beak to eat the seeds, so it decided to exercise its beak …” it can also be an impediment to learning (Evans et al., 2010). Yet, we argue that when purposeful thinking is reframed as a naturalistic goal—an intrinsic one—that satisfies the need to survive in a changed environment, it provides a crucial stepping-stone, paving the way to the core mechanism of evolutionary change, natural selection. This ability to distinguish between the needs of an organism and its desires or wants could jump-start this understanding (Evans, 2008).
Likewise, an anthropomorphic framework provides several analogies that may jump-start a grasp of the origins of species. Children who respond to the question of “How did it get here?” with an artificialist explanation (“someone made it”) appear to demonstrate a grasp of a fundamental issue: that such species did not previously exist. They provide an explanation that is consistent with their understanding of the origins of artifacts, from cookies to art. Confronting the existential nature of such questions may well be a developmental landmark, as this insight provides the basis for natural as well as supernatural explanations of the origins of living kinds (Evans, Mull, & Poling 2002). The challenge here is to go beyond this anthropomorphic framing and address the issue of how species can arise through natural rather than supernatural means.
Briefly, we shall mention some examples of task and environmental constraints that should be taken into consideration when designing formal or informal learning experiences around a potential learning progression for evolution. Studies of U.S. adults’ beliefs about the origin of species indicate that the inclusion of humans as the target species is most likely to elicit creationist explanations. Even adults who frequent museums of natural history are more likely to reject an evolutionary explanation for human origins than for other origins of other species, though the rate of rejection is much lower in such samples (Evans et al., 2010; Spiegel et al., 2006). What is even more surprising is that when study participants were asked whether humans, other mammals (such as deer), and butterflies and frogs may have descended from a completely different ancestor, they are most likely to endorse this proposition for animals that undergo metamorphosis, and least likely to accept it for humans. If asked about whether God created these animals, the reverse pattern is seen (Evans, 2008). Such findings suggest that establishing a developmental learning progression for evolution is constrained by the kinds of tasks (specifically the kinds of animals) that may be included in the learning activity. They also demonstrate that the ability to shift between explanations, sometimes endorsing two or more explanations simultaneously, is a characteristic of this developmental learning progression.
As for environmental constraints, clearly naturalistic contexts (e.g., science museums) are more likely than religious contexts to elicit naturalistic explanations for biological change. At the extreme we see that individuals who are raised in fundamentalist homes and schools are the least likely to endorse naturalistic explanations of origins. These kinds of environments are most likely to elicit explanations that focus on the unchanging nature of the world to the detriment of any explanation for biological change (Evans, 2001, 2008; Evans et al., 2010). Children (Evans, 2001) and adults (Evans et al., 2010) from Christian fundamentalist communities may even resist the (typically intuitive) idea that an animal changes because it wants to or needs to. Indeed, this denial of intrinsic need-based change may give the impression of sophisticated reasoning, but, in fact, it stems from an extreme version of a belief in a designed world: “God made it that way, so it can't change” (Evans, 2001, p. 254).
Principles 4–6: Dual Process Theory, Misconceptions, Coexistent Explanations
The above analysis indicates that, in effect, a developmental learning progression has the potential of charting the emergence of two distinct patterns: (1) changes in learners’ intuitive reasoning patterns as they gradually assimilate pieces of knowledge about the natural world, and (2) the gradual acquisition of a scientific understanding of a particular phenomenon. We have argued elsewhere (Evans & Lane, 2011), that these patterns of change, the intuitive and the scientific, map onto the (p.189) System 1 and System 2 thinking of dual process theory (Stanovich, Toplak, & West, 2008). Moreover, the evidence to date suggests that these might be a continuum (Evans & Lane, 2011). As learners struggle to understand a domain of expertise, they automatically and unreflectively recruit resources derived from their intuitive theories to bear on the problem (System 1 processing). A more reflective and abstract scientific understanding emerges out of these struggles (System 2 processing). The apparent misconceptions exhibited by the learner are consequences of the application of their intuitive theories. These misconceptions, while incorrect from the perspective of the scientist, represent a genuine engagement with the problem and, moreover, they are often locally coherent in that they provide solutions that reflect the integration of the conceptual resources of the learner (Evans et al., 2010).
A characteristic feature of this learning process is the appearance of coexistent explanations (Legare, Evans, Rosengren, & Harris, in press). For example, synthetic explanations in which scientific and intuitive explanations are integrated into a single explanation have been extensively studied by Vosniadou and her colleagues (e.g., Vosniadou, Vamvakoussi, & Skopeliti, 2008). Moreover, as described earlier, theological and scientific explanations can also be combined (Legare et al., in press). Importantly, even though experts use scientific explanations most of the time, they often revert to a more intuitive structure, indicating that intuitive concepts continue to play a role in the thinking of the scientifically literate (Evans & Lane, 2011). In a study of museum visitors’ reasoning about seven diverse evolutionary problems, all the visitors used coexistent explanations (see Evans et al., 2010; Diamond et al., this volume) with a synthesis of intuitive and scientific explanations being the most prevalent pattern.
These three learning principles highlight the core difference between developmental learning progressions and the learning progressions described in more formal education contexts. For the former, but not the latter, it is just as important to describe changes in the intuitive reasoning patterns as it is to describe the acquisition of scientific reasoning. Charting the emergence of an intuitive and a scientific understanding of a topic simultaneously is, however, a formidable task. Next, we demonstrate how these learning principles can be applied to developmental learning progressions for common descent and natural selection, with the aim of bridging the gap between everyday intuition and scientific reasoning. Potentially, this approach might yield strategies for bringing about conceptual change. By encouraging learners to reflect on the nature of their intuitive reasoning capacities, it should make it easier for them to recognize how such intuitions might hinder, as well as help, their understanding of the science.
Principle 7: Emerging Conceptual Structures—Developmental Learning Progressions
At least for evolutionary theory, there appear to be two major ways in which the acquisition of counterintuitive ideas is accomplished. One is via a series of steps in (p.190) which an intermediate problem is solved at each step of the process, with the counterintuitive nature of the targeted explanation minimized at each step. A second way, is via a framework shift. Though the overall effect is one of radical conceptual change with either mode, none of these intermediate steps necessitates more than a minimal change.
I. Common Descent
To jump-start learners’ thinking about evolutionary change, the most obvious analogy that has been shown to stimulate learning is one derived from children's (and adults’) experiences with other people: the developmental analogy. Individual developmental change over a lifetime can be used to scaffold the idea of phylogenetic change. This provides an example of a step-like process of conceptual change. Both individual and phylogenetic change are often conceived of in terms of the realization of innate potential (see Gelman & Rhodes, this volume). As an organism grows, new characteristics emerge from an earlier state. Such an idea was prevalent historically, prior to Darwinian theory, and is related to the original meaning of the term “evolution”: the unfolding of the innate potential of the organism. Basically, this is an essentialist perspective in which the organism unfolds or progresses toward a predetermined endpoint, with embryonic forms of future generations carried in the female (preformation) (Mayr, 1982). Moreover, as learners are exposed to information about more dramatic changes over the life span, such as metamorphosis, the base analogy in which development is initially conceived of as growth, in which the organism merely gets bigger over time, is then extended to include metamorphosis—a radical developmental change, with the organism transformed over its life span. An understanding of metamorphosis, in turn, paves the way for acceptance of the even more dramatic transformations of evolutionary change (Evans, 2008; Evans & Lane, 2011).
This understanding of common descent necessitates a rejection of a strict essentialist view of species, which is achieved in incremental steps, all of which employ the developmental analogy: growth, metamorphosis and, finally, phylogenetic change. Independently of other known influences, such as the age of the child, parental beliefs, and church affiliation, children and adults who grasp basic concepts of biological change, such as growth and metamorphosis are more likely to accept the idea of common descent (Evans, 2001, 2008). In this case, evolution is treated as a special case of development, with change directed toward an endpoint. For example, an adult museum visitor who was asked why different kinds of HIV were found in an individual originally infected with one kind of HIV, responded: “As they grow they develop into other types of HIV” (Evans et al., 2010, p. 336). This response draws on a developmental analogy, which preserves the idea that the essence of the original HIV is passed on to subsequent kinds of HIV. Thus, a maximally counterintuitive construct, such as common ancestry, is gradually understood via a series of incremental steps that draw on a developmental analogy, which explains change over time in more intuitive manner.
(p.191) Transitional concepts that draw on the developmental analogy have two drawbacks however: (1) they suggest that biological change is directed toward a goal and, (2) that it occurs at the individual rather than at the population level, a basic misconstrual of the mechanism of evolutionary change. Even though the developmental analogy trajectory enshrines “purpose,” the advantages of the analogy are that biological change is conceptualized as an intrinsically driven purpose within a naturalistic framework, one that does not employ a supernatural or extrinsic intentional explanation (Evans, 2008; Evans et al., 2010).
Shifting from an anthropomorphic framework that references the intentional or extrinsic goals of a creator to one that references an intrinsic purpose within a naturalistic framework requires a framework shift, from an intuitive psychology to an intuitive biology. This kind of shift can occur fairly rapidly if children are exposed to a naturalistic context that constrains their interpretation of biological change (an environmental constraint). In some recent research in a science museum setting, for example, elementary school–age children were observed in a pre-post design in which they were randomly assigned to an exhibit on evolution (“Charlie and Kiwi's Evolutionary Adventure,” C&K) or to an equally engaging “control” exhibit that focused on the basic molecules of living things—“Marvelous Molecules” (MM) (Evans & Lane, 2011; Evans, Lane, & Weiss, 2012) To examine children's understanding of the origins of species before and after attending the exhibits children were asked, “How did the very first ___s get here on earth?” for each of three animals, none of which were included in the exhibits (e.g., squirrels). Of particular interest was children's use of creationist (“God made it”) and artificialist (“someone made it”) anthropomorphic reasoning to account for the animals’ existence.
In keeping with their robust intuitive psychology and as found in earlier studies (Evans, 2001; Legare, Lane, & Evans, in press), 5- to 8-year olds were more likely than older elementary school children to use anthropomorphic reasoning. Following exhibit attendance, the younger children decreased their anthropomorphic reasoning significantly more than the older children (p 〈 .01) and children who attended the evolution exhibit decreased their anthropomorphic reasoning more than children who attended the control exhibit (p 〈 .05) (see Figure 8.1). This shift away from an intuitive psychology is not necessarily associated with an increase in biological reasoning. Instead it signifies that the child is less likely to endorse a coexistent reasoning pattern in which both frameworks are elicited simultaneously and, consequently, more likely to endorse a biological framework, exclusively. This framework shift is one of the initial steps in the developmental learning progression, paving the way for the acquisition of more sophisticated biological concepts.
II. Natural Selection
A typical finding across a wide range of studies in formal and informal science education and cognitive psychology is that students of all ages treat members of a particular population as if they are equally likely to change, and that this change not only occurs over a lifetime, but is passed on to their offspring (e.g., Bishop & (p.192)
As described earlier, students who endorse the developmental analogy often fail to note that some members of a population possess features that enable them to thrive in a particular environment (variation), whereas others are less likely to thrive (differential survival) and that those that thrive are more likely to reproduce and pass these advantageous features on to subsequent generations (differential reproduction). This is the sequence of biological events that yields changes in the population over time, the mechanism of natural selection (Mayr, 1982). A key transitional issue for students is their recognition of the critical importance of the changing environment. Even young children grasp structure-function relationships in animal and plant populations (Kelemen, this volume; Metz, Sisk-Hilton, Berson, & Ly, 2010), but what is more difficult to comprehend is the consequences of seemingly minor variations in a particular feature if the environment changes (Evans, 2000).
Using age as a marker for the developmental learning progression, a characteristic sequence of steps has been found across several cross-sectional studies (Evans, 2000, 2001, 2008). First, students must realize that there is a relationship between environmental change and biological change; initially, however, they assume that the individual animal's body changes so that it becomes adapted to the environment (e.g., Bishop & Anderson, 1990). This step, in fact, marks an improvement over the earlier developmental analogy in which change is directed toward a predetermined endpoint, a realization of the innate potential of the organism. The environment-directed change is initially described as a response to the animal's desire to change, (p.193) as if the animal consciously makes this decision, as in the following example given by an adult museum visitor regarding changes in the beaks of the Galapagos finches: ‘‘[They] … had to try and work harder, probably, to develop their beaks’’ (Evans et al., 2010, p. 336).
A subsequent shift from such desire- or want-based reasoning to need-based reasoning, in which reference is made to an intrinsic nonintentional process of change (“it needed to change”) is associated with increasingly sophisticated evolutionary reasoning in children (Legare, Lane, & Evans, in press) and in adults (Evans et al, 2010). In a study of the changes in museum visitors’ understanding of evolution following a visit to an evolution exhibit (Spiegel et al., in press) need-based reasoning increased following the visit while want-based reasoning decreased (Diamond et al., this volume). This disassociation between need- and want-based reasoning was also indicated by the positive correlation between need-based reasoning and natural selection understanding (r ? .66; p 〈 .01) while, in the same sample, there was no significant relationship between want-based reasoning and natural selection (Spiegel et al., in press). Further cross-sectional (Legare, Lane, & Evans, in press) and intervention studies in informal contexts (Spiegel et al., in press) suggest that need-based reasoning is a critical transitional step because it draws attention to the role of the environment in biological change: in order for an organism to thrive in a particular environment, it is necessary that it change. The next steps are to recognize the importance of variation in a population, which then paves the way for a grasp of differential selection and finally differential reproduction (see Figure 8.2) (Legare, Lane, & Evans, in press). The latter steps have also been observed by Metz and her colleagues in their studies of the emergence of students’ understanding of natural selection in a formal education context (Metz et al., 2010).
Drawing children's attention to the critical role of the environment can, in fact, bring about rapid changes in their understanding of natural selection, especially if it is done in conjunction with a child-friendly exhibit on evolutionary change. In the pre-post intervention study, described earlier, elementary school–age children were randomly assigned to two exhibits, one on bird-dinosaur evolution (that emphasized the effects of environmental change: C&K), and another a “control” exhibit on molecules (MM) (Evans, Lane, & Weiss, 2012). At pre- and posttest, children
These examples illustrate the interaction of organismic, task and environmental constraints in the emergence of developmental learning progressions for common descent and natural selection. Both framework shifts from one explanatory system to another and incremental minimally counterintuitive changes in students’ intuitive explanations play a role in the emergence of these conceptual systems. While the initial steps have been clarified with respect to both of these constructs, much more precise work remains to be done. In particular, it is unclear exactly how intuitive and scientific explanations are linked and what further steps need to be taken to integrate the two key constructs of common descent and natural selection.
Conclusion: Implications for Science Education
In this chapter, we have outlined the requirements for a developmental learning progression and how it differs from the learning progressions currently being constructed by researchers working in formal education. Of the various differences, two are major. A developmental learning progression (1) places greater emphasis on children's earliest explanations of a domain, in this case biological evolution, and (2) has an endpoint defined more by the research demonstrating the educated (p.195) public's interpretation of the core ideas of the discipline, and less by the detailed curricular demands of the discipline. What does a well-informed member of the public remember about a particular scientific domain, long after he or she has been immersed in courses on the topic? In terms of scientific literacy, for biological evolution it is crucial that more members of the public attain a level of understanding that serves them well as they make decisions about their health, their use of agricultural products, vaccines, and the role of humans in the conservation of the natural world. Currently, only about a third of the U.S. public has this kind of knowledge. This is not an expert's level of understanding; we describe it as informed. Novices, in contrast, are more likely to continue to endorse intuitive explanations of evolutionary change, also found in early childhood.
Our broader approach has been to consider the role of constraints in the learning situation. Alteration of environmental and task constraints changes the influence of particular organismic constraints that the learner brings to bear on the task in hand. Of crucial importance here is the research demonstrating the learners of all ages potentially access multiple explanatory frameworks, even those that might seem diametrically opposed, such as creationism and the evolutionary mechanism of natural selection. Thus the learning process requires not only the acquisition of counterintuitive scientific explanations, but also the ability to discriminate between explanations, to suppress some and privilege others depending on the context. In some cases an intuitive explanation works just as well, and informed members of the public as well as experts might well resort to such a framework, even though they are perfectly aware of the science. We have also argued that dual process theory maps well onto a developmental learning progression. The beginning of a learning progression, the foundational explanatory frameworks, maps onto the intuitive level, the System 1 framework. As learners becomes increasingly knowledgeable and more consciously aware of the science in a particular domain they are better able to shift from an intuitive framework, the anchoring framework of the science, to more effectively utilize the reflective system (System 2) of dual process theory. Once elaborated in further studies, this approach has the potential for providing the basis for successful learning interventions that foster conceptual change.
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