Paradigms of Interactive Systems and Human-Computer Interaction

Usability and the Definition of Paradigms

The primary objective of an interactive system is to allow the user to achieve particular goals within a specific application domain, meaning the system must be usable.
Designers face two fundamental questions regarding interactive systems:
1. How can an interactive system be developed to ensure its usability?
2. How can the usability of an interactive system be demonstrated or measured?
One approach to answering these questions is through the use of paradigms: successful interactive systems that are commonly believed to enhance usability and serve as models for the development of future products.

Time Sharing

In the $1960s$ , research shifted toward the concept of time sharing, where a single computer could support multiple users simultaneously.
Before time sharing, programmers were restricted to batch sessions. In this model, complete jobs were submitted on punched cards or paper tape to an operator who ran them individually.
Time sharing transformed programming into a truly interactive venture. This led to the emergence of a subculture known as "hackers"—masters of detail who enjoyed understanding and navigating complexity.
While initial time-sharing systems were meant to augment the programming capabilities of early hackers, they marked a significant stage in computer applications for broader human use.
The shift moved away from interaction as a pre-planned activity with a complete set of instructions laid out for the computer to follow. Instead, a truly interactive exchange between programmer and computer became possible.
The computer began to function as a dedicated partner to each individual user. This increased throughput of information allowed humans to become reactive and spontaneous collaborators.

Multi-modality

A multi-modal interactive system relies on the use of multiple human communication channels. Each channel used by the person is referred to as a modality of interaction.
In a broad sense, all interactive systems are multi-modal because humans have always utilized visual and haptic (touch) channels to manipulate computers. Audio channels are also used, such as when a user listens to hear if the computer is running properly.
Genuine multi-modal systems rely heavily on the simultaneous use of multiple communication channels for both input and output.
Humans naturally process information using different channels simultaneously. For example, pointing to a person while saying "you" combines touch/gesture and voice to articulate and understand directions easily.
Designers aim to mimic this flexibility by extending the input and output expressions supported by an interactive system. An example is modifying a gesture made with a pointing device by speaking to indicate a specific operation to be performed on a selected object.

Computer-Supported Cooperative Work (CSCW)

The establishment of the first computer networks in the $1960s$ allowed communication between separate machines.
Personal computing initially focused on providing individuals enough power to be liberated from "dumb terminals" attached to time-sharing systems.
As networks became widespread, individuals kept their powerful workstations but sought to reconnect with others in their immediate environment and globally.
This reconnection led to the emergence of Computer-Supported Cooperative Work (CSCW), or collaboration between individuals via the computer.
The main distinction for CSCW systems is that designers can no longer neglect the society in which a single user operates; the needs of many must be represented in one product.
Email is a primary example of a CSCW system. It uses a metaphor where individuals at separate locations communicate via electronic messages, similar to conventional postal systems.
- A user composes a message and "posts" it to another user's electronic mail address.
- When the message arrives, the recipient is informed it is in their "mailbox."
- The major advantage of email is speed; communication turnarounds across the world occur in the order of $minutes$ , compared to $weeks$ for traditional post.
Email is considered an asynchronous CSCW system because participants do not have to be working at the same time for delivery to occur.
Synchronous communication requires simultaneous participation from both the sender and recipient, such as a telephone conversation.
CSCW systems specifically built to support users working in groups are referred to as groupware.

The World Wide Web (WWW)

The World Wide Web (WWW or the web) is built on top of the internet. It provides an easy-to-use, predominantly graphical interface to information while hiding complexities like transmission protocols and remote data access.
The internet is a collection of computers linked by data connections, ranging from slow telephone lines and modems to high-bandwidth optical connections.
Internet communication uses common protocols such as TCP/IP and addressing systems like IP addresses and domain names.
The web adds its own layers: the network protocol (http), a standard markup notation for page layout (HTML), and a global naming scheme (Uniform Resource Locators or URLs).
Web pages contain text, color images, movies, sound, and hypertext links to other pages. These hypermedia documents can be published by anyone with internet access.
History of the Web:
- Conceived in $1989$ by Tim Berners-Lee at CERN (European Particle Physics Laboratory) to distribute scientific data among physicists.
- In $1991$ , the first text-based web browser was released.
- In early $1993$ , graphical web browsers emerged, most notably Mosaic, developed by Marc Andreesen at the National Center for Supercomputer Applications (NCSA) in Champaign, Illinois.
- Mosaic's release triggered the meteoric growth of the web, which eventually dominated internet traffic.
The web is a social phenomenon, creating a "global village" and virtual social environment that challenges the view of computing as an antisocial activity.
It emphasizes liberality and equality regarding gender, race, and disability. While demographics are reaching gender parity, the majority of websites are still hosted in the United States. The web has also become a massive venue for corporate images and e-commerce.

Agent-based Interfaces

Software agents act on behalf of users in the electronic world, similar to how estate agents or travel agents work for customers in the physical world.
- Examples: Email agents that filter mail and web crawlers that search for interesting documents.
Agents can perform repetitive tasks, respond to events when the user is absent, and learn from user actions.
A major challenge is developing a language between human and agent to express intentions, especially since error feedback may not be received until after effects are irreversible.
Some agents use artificial intelligence (AI) to learn from user behavior.
- Example: Eager is an AI that watches users in HyperCard applications. When it detects repeated actions, a smiling cat icon appears to suggest the next step. The user can accept, ignore, or eventually instruct Eager to complete an entire sequence.

Sensor-based and Context-aware Interaction

Traditional interaction involves the user explicitly telling the computer what to do. Context-aware computing relies on implicit interaction.
In this model, a sensor-enhanced environment uses heuristics and semi-intelligent means to predict what would be useful for the user.
The data and the resulting inferences are often fuzzy, probabilistic, and uncertain.
Because sensing context is an imperfect activity, applications should follow the principles of appropriate intelligence:
1. Be right as often as possible and be useful when acting on correct predictions.
2. Do not cause inordinate problems if an action results from a wrong prediction.

Ubiquitous Computing (Pervasive Computing)

For the past $50$ years, paradigms have mostly viewed computers as boxes on desks or in labs. Physical interfaces evolved from noisy teletypes to graphical displays with WIMP (Windows, Icons, Menus, Pointers) or natural language interfaces, but the user still had to physically go to the computer.
In the late $1980s$ , researchers at Xerox PARC, led by Mark Weiser, aimed to move interaction away from the desktop and into everyday life.
Mark Weiser asserted: "The most profound technologies are those that disappear. They weave themselves into the fabric of everyday life until they are indistinguishable from it."
This inspired the field of ubiquitous computing, also known as pervasive computing (a term coined by IBM).
The goal is to create a computing infrastructure that permeates the physical environment so thoroughly that users no longer notice the computer.
The electric motor serves as an analogy: initially large and noticeable, it is now found in so many household items that it is effectively invisible and ubiquitous.