People are surrounded by a multitude of objects and machines that they interact with every day.

Nearly 20,000 of them, according to Don Norman’s The Psychology of Everyday Things. Simple things such as switches, writing instruments, clothes with varying functions and styles, fixtures, bulbs, sockets, screws, furniture, food utensils, watches, scissors, paper clips — are all examples of products that need ergonomic design.

Then there is a category of machines that has become almost eponymous with the modern day lifestyle — computers.

Norman makes a calculation that supposes each of these objects takes about a minute to learn. Then we spend 20,000 minutes learning how to use all of them. That is 333 hours, or eight forty-hour weeks. And this does not account for the fact that we are encountering objects and machines, unexpectedly, on a daily basis.

As if understanding and learning to use the objects and machines weren’t enough, scientists must also account for the idea that products may not be conducive for human use over the long term. This is where ergonomics weighs in.

According to the International Ergonomics Association, “ergonomics is the scientific discipline concerned with the understanding of interactions among humans and other elements of a system, and the profession that applies theory, principles, data and methods to design in order to optimize human well-being and overall system performance.”

The field is broadly split into physical, cognitive and organizational ergonomics.

Physical and cognitive ergonomics come into play when designing computers and their interfaces for human use. Fields as diverse as industrial engineering, psychology and computer science have to come together to solve problems that arise as a result of Human-Computer Interoperability (HCI).

Dr. Christopher Mayhorn, an assistant professor in the psychology department at N.C. State does extensive research in these fields.

“Psychology fits on the ‘human side’ of human-computer interaction,” he said.

According to Mayhorn, people on the psychology side of ergonomics spend much of their time doing things like “needs analysis” to answer questions such as what functions a device should perform, why errors occur, what the best way is to train people on using a device and how device designs might be improved in the future.

The field of HCI comprises the study, design, construction and evaluation of interfaces between humans and computers, said Thomas Horton, a doctorate student in computer science.

“Good interface design is important for a variety of reasons,” he said. “People should have a positive experience when using a computer. One of the many factors that led to the huge success of Apple’s iPod is the ease of use of its interface.”

In Horton’s view, computer scientists design and implement both hardware and software interfaces. HCI is also involved with a wide range of other areas in computer science, such as computer graphics and artificial intelligence.

The occupational safety and health administration (OSHA) published an “ergonomics program” in 1999. It details the significant risk of musculoskeletal disorders confronting employees in workplaces.

When dealing with computers, the OSHA report examines the following possibilities for MSDs: intensive keying of information into the computer, improper design of desks for computer use and the fact that operators rest their forearms and wrists on the edge of the computer table, reducing blood flow and movement.

Work-related MSDs currently account for one-third of all occupational injuries and illnesses reported to the Bureau of Labor Statistics every year, according to OSHA. These injuries account for nearly $1 of every $3 spent for workers’ compensations, with employers paying more than $15-$20 billion every year.

NCSU’s industrial engineering department has an ergonomics lab that conducts research in the areas of occupational biomechanics, occupational safety and cognitive ergonomics.

The goals of the program include educating engineers about the potential impact various decisions can have on humans that operate those systems, according to the program’s Web site. One primary focus of the lab is a program in occupational safety and ergonomics, offered to masters students.

According to Horton, safety can have a perspective different from that of just personal injury.

“Computers are used by hospitals, airlines and the military to make decisions that affect the lives of people every day,” he said. “If a display isn’t clear, or if a system doesn’t have protections against user error, the consequences can be tragic.”

Apart from the physical problems that might arise when humans and computers are thrown together, there is a subtler and yet more important problem — that of cognition and lack of understanding, and all the problems and confusion that spews forth as a result.

Norman points out that machines, including computers, never err. When computers do err, it is either because a part has failed or because of human error, either in design specification, programming or faulty construction. Humans, on the other hand, do err, primarily because they are asked to perform unnatural acts — detailed calculations, remembering the details of some lengthy sequence or statement or performing precise additions or repetitions.

Horton would like to draw distinctions between the types of users — novices versus experts.

“Novice users have little experience with the application and often no experience with computers at all,” he said. “They will be prone to mistakes, often feel lost and even afraid to work with a system they do not understand at all.”

“Expert users, on the other hand, may have been using similar systems for years — they are experienced, usually want to perform a task as quickly as possible and often resist changes to the system.”

Mayhorn said that he works on topics that affect human-computer interactions in his lab. He has worked on how to train older people to use computer technology and using PDAs as memory aids for older people.

He also studies web design factors that influence information credibility on the Internet, what people like and dislike about instant messenger systems and whether emotions facilitate computer-mediated communication. Design of computer security warnings and how people make computer security-related decisions also come under the purview of his studies.

The visual aspect in the design of computers, software and other objects humans use is also important, such as Horton’s example of the iPod.

Horton believes more collaboration between HCI and ergonomics is visible in the industry, where an off-the-shelf interface cannot handle the unique requirements of the task, leading to a whole new hardware/software solution being found.

He believes the following about HCI as a field of study.

“HCI is a really cool field of study and there are a lot of opportunities for personal creativity in interface design,” he said. “A lot of HCI is hard science, but there is also a degree of intuition and experience required that makes interface design something of an art form.”