Describe what psychologists have learned about human factors in work design. ‘Human factors in work design’ refers to a specialty area of I/O psychology concerning the design and development of tools, machines, work systems and workplaces, such that their characteristics correspond with the skills and abilities of the worker. This answer will focus on the efficient design of ‘operator-machine systems’ and the workspace. A primary concern for human factors psychologists is the design of ‘operator-machine system’, which is the two-way interaction between workers and tools, collaborating to perform a task.
Chapanis (1976) has provided an outline of the various elements of the operator-machine system: the human system of the operator-machine system comprises of sensing, information processing/decision-making and controlling; whereas, the machine system consists of controls, operation and displays. In the following paragraphs, each element of this interaction will be explored in detail. In the initial step of the interaction, the machine communicates information regarding its operational status to the operator on mechanical devices called displays.
Displays are of several types, one of which is the visual display. The visual display can provide detailed and complex information to the operator. It can take one of three forms: quantitative (that gives precise numerical values), qualitative (that provides characteristics of machine operation) and check-reading (that indicates whether a machine system is on or off or functioning normally or abnormally). Visual displays are adequate for use in such as situations when a long or complex message or one that does not require immediate attention needs to be conveyed.
Also, they are used in work situations in which the operator will be focused on the displays and in environments too noisy for auditory displays. Human factors psychologists adhere to three basic principles when placing and arranging visual displays as both factors greatly influence their effectiveness (Wickens et al. , 1995). First, visual displays must always be in the line of sight of the operator to ensure that the operator receives the information and work performance is not compromised. Second, displays providing related information should be grouped together.
Third, displays that need to read sequentially should be placed in reading order. Auditory displays, which can be as basic as buzzers or as advanced as computer-generated ‘synthetic speech’, are primarily used to provide warnings. They are used in situations where visual displays are not adequate, i. e. , when an urgent message or one that is continuously changing (as is the case with aircraft flight path information) or one that deals with a specific moment (such as a gun fired to start a race) needs to be conveyed.
They are also ideal for work situations in which the operator needs to move in all directions and in dark environments where visual information would be difficult to see. In order for auditory displays to be effective, Edworthy (1994) suggests that they must be at the appropriate sound and volume level, i. e. , neither so soft that they go unheard, nor so loud that they distract workers. In addition to this, auditory warning displays need to be psychologically appropriate. For instance, short bursts of noise are more likely to be perceived as warning signals than a single bell-type sound.
Once the machine has shown output via displays, the worker engages in a three-step information processing and decision making process. The first step is the perceptual stage, in which the worker receives visual and auditory data through the senses. The second step is the cognitive stage, in which the worker classifies and interprets the sensory input. The worker first compares the sensory input to some cognitively stored information, including past experience with the machine and knowledge gleaned from training
Then, it is classified it into a category that corresponds with the kind of information provided, e. g. , a buzzer may be classified as either ‘status information’ or ‘warning’. Finally, the worker refers to the specific language used by the machine to interpret its messages. The third step is the action stage, in which the worker uses memory and/or training to select one of several courses of action that can be taken, and communicates the decision by manipulating controls (Kantowitz, 1989). Machine controls are mechanical devices such as knobs that an operator uses to control machine functions.
One type of machine controls are keyboard controls, which can take the form of an alphabetic or numeric keyboard. Numeric keyboards are either arranged as a string of numbers at the top row of a keyboard, or as three rows of three digit keys in either ascending (as with telephone) or descending order (as is the case with calculators). Alphabetic keyboards can either take the QWERTY format, in which vowels are scattered all over the keyboard, or the DVORAK one, in which the vowels are arranged in the home row and are all activated by the left hand.
The latter is more efficient for touch typing as over 3000 words can be typed using letters from the home row alone (as opposed to the 120 words using QWERTY keyboard), which may increase typing speed by 5 to 20 percent (Sander et al. , 1993). Certain basic principles have to be followed in design and selection of controls in order for operator decisions to be communicated effectively. First, controls should be matched to the operator’s body.
To prevent operator’s hands from being overloaded, only controls requiring great precision should be hand-operated; other simple operations should be controlled by foot. Second, control movements should mirror the machine actions they produce. Third, related controls should be combined so that in one action, the operator can change the operation of both systems. Fourth, controls should be clearly marked for rapid identification.
Not only can they be visually recognized, some controls may require shape-coded controls that can be quickly recognized by touch. Fifth, the placement of important controls on similar machine systems should be standardized, especially when a worker is required to alternate between several similar machines regularly. Sixth, controls, especially emergency controls, should be adequately spaced and arranged to avoid unintentional activation.