Human Input and Output Channels

After having dealt with the computer, the other side of human-computer interaction will be discussed. Similar to the approach adopted previously, human input and output "devices" will be discussed first. Afterwards, human information storage and processing will be sketched out.
According to Dix et al., humans receive and send information via the following channels when interacting with a computer (9-24):³⁴

• visual channel
• auditory channel
• haptic channel
• movement

Dix et al describe these channels in a simplified model of human I/O channels, dealing with the user as an information processing system (10). This system is limited in its capacity to process information, which is compensated by various means of interpretation and expectations. In other words, the user's interpretation and expectation determine what the user sees (17) and hears (22).
It is necessary to mention touch and movement due to their importance in using a keyboard and a mouse.³⁵ While the speed and accuracy of movements have to be considered with respect to the design and size of icons, the haptic channel provides users with information concerning the position of their hands, or, more accurately, their fingers when using a mouse or a keyboard (22-24).³⁶