features at all, but rather lie outside the materiality of the object.

Brenda Laurel suggests that interactivity can be thought of as sitting on the three axes, of ‘frequency’, ‘range’, and ‘significance’. 3 Frequency represents the number of occasions on which the user interacts with the computer. Range represents the number of distinct choices that are available, while significance represents the degree to which the choices made by the user alters the outcome. Thus: “A not-so interactive computer game judged by these standards would only let you do something once in a while, only give you a few things to choose from, and the things you could choose wouldn’t make much difference to the whole action (or produce significant changes to the state of the underlying system). A very interactive computer game (or desktop or flight simulator) would let you do something that really mattered at any time, and it could be anything you could think of.” 3

As we reflect on the complexities of preserving the key characteristics of artifacts with a high degree of meaningful interactivity, it becomes clear that interaction gives the operation of computers a certain degree of ephemerality, and variability, which in turn produces highly individualized, and potentially unique, behaviors in computer systems. Thus, the behavior of computers may well be impossible to reproduce in full on subsequent occasions, even supposing the software designer/author were motivated to do so. Laurel characterizes the operation of computers as ‘performative’ 2 and comparable to theatre. So just as no two performances in a theater are (or can be) exactly alike, computer systems whose core behaviors are dependent on the variable input of users may also be unique. The degree to which this is actually so in practice depends crucially on the sort of interaction the computer system in question permits.

In many cases it is more sensible to
think of software in terms of what it
does, rather than in terms of the lines
of code that constitute a program, or
the hardware on which the software
runs. Construed this way, the hu-
man component of human-computer
formation which publically and freely
available. However, as one begins to
engage seriously with preservation is-
sues, it does not take long to come up
against problems that are much more
difficult to address, and which are in-
creasingly common.

I have recently been concerned by the preservation challenges presented when dealing with interactivity and ephemerality. The drive toward providing ever more complex and nuanced forms of computer interactivity is not new. Indeed, it has been around right from the earliest days of computing, Ivan Sutherland’s Sketchpad represented a significant early step, and Sutherland is usually now remembered as the founding father in computer interaction. The history can be traced through Doug Engelbart’s visionary effort during the 1950s to “augment the human intellect” by making available a vast amount of human knowledge via highly responsive workstations. Engelbart’s so-called NLS (oNLine System), which was developed courtesy of an ARPA grant facilitated by Sutherland ( working under the direction of J.C.R. Licklider), was first demonstrated in 1968 in what came to be called the “Mother of All Demos.”a This remarkable event featured the introduction of the computer mouse, video conferencing, teleconferencing, hypertext, word processing, hypermedia, object addressing and dynamic file linking, bootstrapping, and a collaborative real-time editor.

During the 1970s, Apple did a great deal of work to move interactivity technology out of the laboratory into the living room, and today the ideas put forward by Licklider, Sutherland, and Engelbart are considered commonplace. Development continues of course, and Virtual Reality systems are just a recent manifestation of the increasingly sophisticated ways we are able to interact with computers.

From the perspective of the arts, Oliver Grau1 has argued that the development of what he calls ‘illusionary visual space’ is part of the overall art history of illusion and immersion, and draws connections with interactive art, interface design, agents, telepresence, and image evolution.

 

a Ten clips from the Mother of All Demos are available at http://bit.ly/2epzIs2.

The existence of complex interactivity affordances in modern computer systems has a significant impact on how we think, and can think about computers, and this in turn has consequences for our conception of what we are trying to preserve and later make accessible for future generations.

Among computer scientists, the tendency has traditionally been to concentrate on the tangible or the physical.b Thus, preserving (say) the financial records of a company would typically be treated as a series of tasks involving ensuring the bits that comprise the company accounts package and its associated data are saved on a stable medium, and stored in a safe place. These in turn would need to be periodically updated to run on new generations of hardware when they become available (migration) or might subject to virtualization or emulation. While the implied processes of careful analysis, storage, preservation management, and access provision, usually work well for financial systems and text documents, they serve us much less well when human-computer interaction offers users the opportunity to influence fundamentally the performance of software. Grau’s notion of illusionary visual space draws attention to the fact that sometimes the most significant features of an object, and those that we would be the most concerned to preserve, are not tangible

 

b Jerry McDonough has written a number of pieces showing how preservation of bits is in many ways the least difficult of the preservation challenges before us. See, for example, McDonough. 5

The drive toward
providing ever
more complex
and nuanced
forms of computer
interactivity
is not new.