Interpreting Graphs as Emergent Competence: A Cultural-Historical Approach

H: We report on a new study conducted in a biology laboratory where the investigators conduct microphotospectrometry of fish retina. Because of the cutting-edge nature of the research, it is often not clear what a particular graph means, which aspects are meaningful signal, and which aspects constitute noise or artifact. By coming to understand the emergence of graph readings in this complex situation, we illuminate the discussion of graphs and graphing competencies where social science researchers’ presuppositions cloud the pertinent epistemological issues. Research on graphing ordinarily asked participants to make inferences about the meaning of graphs without ascertaining that these participants are actually familiar with the conventional rules established by the (scientific) community or with the phenomena that said to be represented in the graph. Recent research showed that in such situations, not only students but also experienced scientists have difficulties reading graphs when they are not familiar with conventions or the phenomena (Roth & Bowen, 2001a; Roth, Bowen, & Masciotra, in press). On the other hand, when individuals are explaining graphs that have arisen from their own or similar work, they are highly competent. The Graphing as emergent competence 2 present study further illuminates the emergence of competent graph use and graph interpretation and shows how scientists in activity appropriate (internalize), in some situations and under certain circumstances, previously-external tools of graphical analysis. As a result, scientists’ reading of graphs is intimately tied to an understanding of the phenomena and instruments involved in the data collection. Our research provides evidence that competent reading of graphs is the result of a historical process in which previous results (and understanding) become internalized (in subject or tool [e.g., computer]). At any one point in time, competent graph reading is based on built-in prior results of human activity. In this paper, we provide evidence for these aspects of reading graphs and the process of internalization. The following excerpt raises the central problematic addressed in this paper and exemplifies our approach and results. In cutting-edge scientific work, the nature of a graph is often ambiguous. Its exact nature (as fact or artifact) is yet-to-be determined. MR, being new to the laboratory, asked whether the graph displayed on the monitor was a sign that an UV cone had been in the collimator. MR: Is this a UV cone? TH: I think there is a potential hump here [on right shoulder] and a little hump there [next to major peak] but it is very hard to read. CH: °You need the spectrum°, to put on. TH: You want to rescan it? CH: No, go on to another cell. There is too much in here that I don’t want to look at. TH: OK Rather than making a definite interpretation, the research associate TH suggested that there are peaks (“humps”) potentially of interest. The senior researcher CH, who also prepared the specimen in the microphotospectrometer, suggested that another spectrum Graphing as emergent competence 3 not presently available on the monitor “had to be put on,” presumably to facilitate the interpretation. TH proposed to rescan the cell, but CH decided to go on and to try another specimen—the searched-for signal was probably not there. Here, the two scientists collaboratively achieved the reading of the graph. This reading was not based on pure inference but was mediated by the graphs displayed in the following ethnographic field note (Figure 1). The shape of the curve in the UV region [left]. The high values are legitimate given that the photoproducts resulting from chemical changes in the retina are expected there. There is also a β absorption effect. Only the right part of the spectrum is really of interest [bottom], and it is this part that is plotted in the curves on the board in front of the lab. There is an increased amount of UV absorption due to bleaching (see middle graph). This absorption is legitimate, both because of the photoproducts and because of the β spectrum. Figure 1. Graphs and conceptual underpinning that mediate the graph-reading episode. Accordingly, chemical changes in the retina produce substances that absorb light in the UV part of the spectrum, thereby cluttering any expected peak from a UV-absorbing cone. Although not made explicit, the graph reading in the above episode embodies the scientists’ understanding and prior experience with the graphs on the right. Because of their extensive experience, they do not make the graphs on the right explicit. However, in other situations that we present in the paper, graphs are actually made visible on the computer monitor so that a direct comparison between a previous and the to-beGraphing as emergent competence 4 interpreted graph is made possible. Of course, the relationship of the scientists to the graph, the object of their inquiry, was also mediated by the scientific community, which expects them to produce clear signals and “unambiguous” evidence for the phenomenon of interest. What is to be taken as a salient aspect of a graph is not known a priori that is, without knowledge of the natural system. All evidence shows that graphs, graph-producing tools, and familiarity with the phenomenon mutually constitute and stabilize each other. This became quite clear when MR first joined the biological laboratory. Despite his physics and statistics background and despite years of research on the topic of graphing, MR could not correctly interpret the graphs that were the result of a data run. That is, interpretation could not be based on a purely inductive process. Even the nature of the relevant graphical feature was not evident so that during the early part of our research, MR was frequently attuned to features not at all salient to the resident scientists. The difficulties faced by a novice reader of the graphs become apparent from the four examples in Figure 2 and the collectively achieved interpretations. In the first two graphs of Figure 2, analysts might be tempted to identify two features each that appear at about the same locations in the wavelength spectrum. However, the analysis of the laboratory interactions between the two scientists who collected and online interpreted these graphs, left little doubt that the left (Figure 2a) pertained to a blue retinal cone whereas the right (Figure 2b) pertained to a red retinal cone. That is, in the first graph what was salient to the scientists is the first, smaller peak whereas in the second, the right (smaller) peak predominated in their perception and interpretation. Yet, a quick inspection of the two graphs shows that the left peaks in both are almost identical. Graphing as emergent competence 5 How then do the scientist come to look at the right graph and apparently looking through its left peak without paying any attention to it as if it was transparent or even invisible to the eye? One might ask, how do scientists come to the point of articulating the left hump in the first graph and the right hump in the second graph as the signal and the other hump as noise, respectively? When scientists began researching a particular phenomenon they did not and could not know what the “right” peaks are, that is, how to “correctly” interpret the graphs that they have at hand. And yet, after some time they developed a competence that allowed them to make assessments, among others, increasingly quickly and without hesitation.