Asia-Pacific Forum on Science Learning and Teaching, Volume 15, Issue 2, Article 5 (Jun., 2014)
The definitions of visualization, representation and model
Visual communication is essential to unfolding ideas in science lessons, and visualization has been widely used in science education to represent scientific concepts for many years (Cook, 2006; Gilbert, 2008). To date, there are a number of educational studies dealing with visualization, representation and model. However, the sameness and differences of these three terms have not been discussed. In this article, we feel the need to define and discuss the three terms with examples to build our knowledge upon a common ground.
The definition of visualization, representation and model
Today, there are different definitions of visualization, but mainly of the external representation (ER), internal representation (IR) and visualizing process (VP) of cognitive and brain activities. Tufte (1983) views visualization as ER with a systematic demonstration of information via the form of pictures, diagrams, tables, and the like. By the same token, in the later years, colleagues in different research groups have defined visualization as any type of physical representation designed to make an abstract concept visible (Rapp & Kurby, 2008; Uttal & O' Doherty, 2008). Uttal and O’Doherty (2008) indicate that visualization should be thought of as one type of ER that includes photographs, 2-D graphs, diagrams, charts and 3-D models. However, the concept has been slightly shifted by Rapp and Kurby. They claim that, based on visualization, learners construct their mental models, which are related to IR. Gilbert (2008) concludes that visualization has to do with the formation of an IR from an ER, in which the temporal/spatial relationships of the entities from ER are retained in IR. In addition to the notion of ER and IR, Reiner provides different views on visualization and regards visualization as the cognitive and brain processes associated with the act of visualizing rather than as a pictorial representation, which is linked to VP (Reiner, 2008).
Regarding representation, we can say that people create representations through their intention to have one thing stand for something else (P. Bloom & Markson, 1998; Deacon, 1997; DeLoache, 2000; Tomasello, Striano, & Rochat, 1999), that is, a representation is seen as “a structure that stands for something else: a word for an object, a sentence for a state of affairs, a diagram for an arrangement of things, a picture for a scene” (McKendree, Small, Stenning, & Conlon, 2002, p. 59). Moreover, Gilbert (2008) argues that a representation is the depiction of anything and that it can be classified into two groups of ER and IR. Again, an ER is situated in the public sphere with an object of visual, verbal, or symbolic form and an IR is constructed mentally by an individual.
For a specific purpose, a model in science can be developed as a representation to represent a simplification of a phenomenon, and then to be used in the inquiry to develop explanations of the phenomenon (Gilbert, Boulter, & Elmer, 2000). In this sense, a model can be seen as an idea, for example, the scientific model of global warming phenomenon. A model can be also expressed as an ER (physically available to others) or an IR (mentally available by an individual and deemed as a mental model). The transforming process between ER and IR is called modeling process, which is happening in our brain, similar to VP. Only, the modeling process can be a developing process of an idea to explain a phenomenon, and does not necessarily involve a visual model. Similar to visualization and representation, a model of an object (ER) can be different sizes, either smaller than the real object it represents (e.g., of a train), or the same size as the real object is (e.g., of the human body), or bigger than the object in reality (e.g., of a virus).
The sameness and differences of visualization, representation and model
Through Figure 1 together with examples, the sameness and differences of visualization, representation and model are discussed in this section. From the above-mentioned definitions, it is not hard to perceive that the terms of visualization and model share the same arenas of ER, IR and VP, so they are included in the same domain of representation (see the (a) part in Figure 1). Besides the sameness of the cognitive and brain process to bridge ER and IR, visualization and model can also make abstract concepts/complex ideas simplified and explicit through IR and ER. However, there are parts not totally overlapping and that show the differences of visualization, representation and model (see as the (b), (c) and (d) parts in Figure 1). Science educators and/or science education researchers need to be aware of the differences while using the terms concerning visualization, representation and model.
- Some representations cannot be regarded as models, but as visualization (the (b) part in Figure 1). For example, when something flashes in front of our eyes quickly, we can visualize it and have an image of it, termed IR, but we cannot map this image in our brain with any model that we have memorized/saved in our schemas.
- One important feature of a model is that it is recognized and agreed on within a community (i.e. science community) or a majority of people (i.e. in a specific culture). A model can be formed in visual, auditory or tactile modes. Therefore, the (c) part in Figure 1 could be regarded as auditory and tactile modes that are not visible. The various sounds of different species of birds, esp. the sounds made by birds while trying to give signals to other birds, could be the example of (c). However, if the model of birds’ sound signals is transformed and expressed by a notation, it becomes a visual model and is seen as the (a) part in Figure 1.
- A representation is not necessarily a model or a visualization, but just auditory sense or sense of touch to represent some kind of meaning for a person. For example, while hearing a bell ringing, for some persons, it could represent a school bell to remind teachers and students for the start or the end of a lesson. However, for people in another culture or having different experiences with the same bell sound, they have different representations linked to it. This kind of bell sound is not a model to be generalized, but individualized. Another kind of example for the (d) part in Figure 1 could be metaphor, which represents some kind of meaning, but we cannot say that it is a model and even visible. For example, a linguistic metaphor, help words, has been revealed in Swedish students’ non-conventional expression (‘Flopp’) to represent the nitrogen-base of DNA by some Swedish students and that is not a model (Rundgren, Hirsch, Chang Rundgren, & Tibell, 2012). In addition, after the novel, Frankenstein, published 1818, people start using Franken as a prefix to describe ‘‘strange’’ object discovered in nature by scientists like Frankenseeds. In reality, there is no model or visualization to show a Franken object (retrieved on 2014-12-14 from http://scitechvista.most.gov.tw/zh-tw/Articles/C/0/8/10/1/1004.htm), but people could understand the implied meaning.
Figure 1. The relationship of visualization, model and representation.
In sum, ER, IR and cognitive process in the brain are the overlapping parts of (a) as visualization and model in science education. But in the basic science research, (b) and (c) parts are of importance to research progression. To make students learn better regarding a variety of profound scientific concepts, science education researchers, need to investigate more about whether the different forms of ER can be used by teachers to convey scientific models and whether different IR might be created by students considering the different scientific models. Of course, the (d) part of representation is also important to reveal in science education for better science teaching and learning. However, in this article, we emphasize visualization, and more specifically, ER.
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