Haptic Visions. Valerie Hanson
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to attempt certain kinds of rhetorical actions rather than others. (x)
Following how a technology’s affordances create particular responses in users reveals rhetorical possibilities that the affordances encourage, and even create. Extending Miller’s direction, following affordances helps articulate what properties of information and interaction encourage rhetorical actions in operating a particular technology as well as what kinds of rhetorical actions are most encouraged. Tracing the persuasive in the affordances a technology creates thus provides a way of exploring interaction while attending to an instrument’s productive, material rhetorics. Following the affordances a visualization technology creates, then—and going back to Michel Foucault’s architecture of making visible, as discussed in the introduction—helps to identify some of the available possibilities that shape what can become visible.
As I analyze the operating dynamics of the STM in light of their affordances, I also observe the interactions the operating dynamics encourage in relation to four main ways of characterizing interaction from HCI (human-computer interaction) studies in order to explore how the interaction configures possibilities for the user. In a survey of different views of interactivity from the HCI research traditions, Sally McMillan explains that the following four ways include three that are based on Claude Shannon’s model of communication as information a sender communicates to receiver: user communicating to computer; computer communicating to user; and an equal, adaptive interaction where “the computer is still in command of the interaction, but that it is more responsive to individual needs” (McMillan 175). The fourth constitutes interaction differently, in terms of what Mihaly Csikszentmihalyi refers to as “flow:” it “represents the user’s perception of the interaction with the medium as playful and exploratory” (qtd. in McMillan 173–4). “Flow” tends to include participation from both sides, so that neither computer nor user occupies either “sender” or “receiver” roles; instead, computer and user take on both roles, and so become co-creators or participants (McMillan 174). As McMillan further describes, flow is
characterized by a state of high user activity in which the computer becomes virtually transparent as individuals ‘lose themselves’ in the computer environment. Virtual reality systems seek this level, but it may also be characteristic of gaming environments and other situations in which the user interfaces seamlessly with the computer. (175)
These four models of interaction present different experiences for users; the interaction models may also generate different patterns of user response, further determining how users interface with the computer through the screen. Comparing STM dynamics to the models of interaction provides a more specific sense of how STM dynamics are structured.
Studies in rhetoric, science, and HCI identify “interactivity” as the structuring of events that involve writers/users, media, knowledge and information, and users/readers in particular configurations. A focus on “interactivity,” then, is also a focus on finding, describing, and analyzing interfaces—places of interaction, boundaries where forces or disparate elements meet. This chapter begins my focus on interactivity as I identify, describe, and analyze interfaces; Chapter 3 and Chapter 4 further analyze interfaces. In the next section, I analyze STM dynamics to identify the affordances that instruments create that, in turn, impact the shaping of inscription practices scientists engage in when using the STM. The STM dynamics influence the form of the inscriptions that help create scientific statements, and so shape nanotechnology and the concept of the atom. The affordances shape rhetorical possibilities inherent in the inscription practices that are also visible in the inscriptions themselves, as I explain below.
Manipulating Atoms: Microscope Interactions
Three main dynamics within extant visualization and instrumental traditions in science and related technologies help constitute the visualization practices of the STM: electron tunneling, raster scanning, and image processing using a graphic user interface (GUI). Each of these three dynamics structures interactions between apparatus, user, data, and the nanoscale; informs how instruments mediate the transformation of phenomena to data and to image; and helps structure how scientists interpret the data in the image. While each of these main dynamics functions separately to some extent, the interactions between the dynamics combine, expanding connections and enhancing the intensities that each may possess alone. The coordinated interactions of the dynamics of electron tunneling, raster scanning, and GUI image processing then enable the STM to function, producing and arranging data about the nanoscale, thus affecting what STM images convey and how the images do so. The coordinated interactions of the STM operating dynamics structure the possibilities for making atoms visible—and also help create the productive rhetorical possibilities of the STM.
Electron Movement: Tunneling Electrons and Interactive Surfaces
One of the major dynamics on which the design of the STM is based relies on the interactions between a conductive surface (composed of a metal, for example) and the microscope tip, as the tip does not contact the surface, but remains about a nanometer away (Mantooth 9). Instead of contact, the interaction between tip and surface is a result of electron tunneling. Tunneling is based on the articulation of electrons as both particles and waves in quantum mechanics, where “each electron behaves like a wave: its position is ‘smeared out’” (Binnig and Rohrer, “The Scanning Tunneling Microscope” 52). The behavior of electrons as both particles and waves allows surface electrons to “tunnel” through the barrier of the vacuum between surface and tip atoms, and thus interact with the electron cloud of the atoms or atoms on the tip. Measurements of the tip’s electron clouds through voltage thus presents a way to understand the surface atoms through the behavior of the behavior of the atoms. Use of electron tunneling as a measurement technique in the STM is part of a broader trend in creating images from non-optical data, and has implications for what is able to be visualized with the instrument.
Electron tunneling is a relatively new idea; the incorporation of electron tunneling into the STM shows how the dynamic fits into the larger story of the development of non-lens-based visualization technologies. In 1960, Ivar Giaever first published the results of demonstrated electron tunneling (Giaver 147–48). For his research, he received the Nobel Prize in 1973. However, scientists did not apply electron tunneling to instrument development until the early 1970s, when Russell Young, John Ward, and Fredric Scire created a machine called the “topografiner” that, like the STM, used electron tunneling and three-dimensional scanning to measure “the microtopography of metallic surfaces,” but used a field emitter instead of a tip to create tunneling conditions (Young, Ward, and Scire 999). The topografiner was not very successful in achieving measurements due to interference from outside vibrations, caused by people walking in the building, for example. In the early 1980s, STM inventors Gerd Binnig and Heinrich Rohrer, along with Christoph Gerber and Edmund Weibel, reduced outside vibrations enough to measure the tunneling and develop the STM (Binnig et al. 178–180).29 The story of how electron tunneling became a measurement technique illustrates the complex mediation required of some visualization technologies, mediation anchored in the practices of a larger community.
The use of electron tunneling to visualize atoms affects what can be measured as well as the relations between the different atoms interacting at the interface of the vacuum. What is measured is the atomic movement that enables electron tunneling, not an object such as an atom. Recording the interactions of electrons with other electrons in a vacuum also transforms the distance between tip and surface electrons into a dynamic interface. To create data points, then, the tip passes across the area to be imaged, sampling the changes in voltage produced by the different densities of electron interactions at different spots. Therefore, the STM maps encounters, local events of tunneling.
One effect of the use of electron tunneling to create measurements is that both tip and sample can affect the interaction (and thus the measurement). For example, the tip’s characteristics can affect the sample and the image produced from the sample, establishing a multi-directional affordance that both creates and structures the dynamic between tip, sample, and resulting image. As STM textbook author Chunli Bai explains: “The size, nature and chemical identity of the tip influence not only the resolution and shape of a STM scan but also the electronic structure to be measured” (9). For example, the conical shapes that form the rim of the Quantum Corral (Figure 4) image are not “what atoms look like;” instead, the