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With time, business enterprises and other public as well as private organisations deployed systems that
were complex in nature and were more powerful with automation. These machines not only process
information, but also have the capabilities to handle certain situations dynamically like humans. For
example, machines deployed in stock exchange, industrial plants, aircrafts, etc.

The journey of interaction between human and a machine used to be very complex but as the evolution
and inventions introduced, it has become a child's play. Lets look at the devices which made it easier.

COMPONENTS OF HUMAN-MACHINE INTERACTION

To perform a dialog between human and a computer system there are three components that are
interconnected— Human, Machine and the interface between them. A computer interface or a program
establishes interaction between the user and computer. HMI mainly focuses on this computer interface.
Humans and computers use very different channel of communication as you can understand from the
data given below:

S.No. Humans Computers
1. Sensory Memory Keyboard/Mouse/Touchpad
2. Short-term memory Speech Recognition

3. Long-term memory Text input devices
4. Visual Perception Eye-tracking

5. Auditory perception Display screens
6. Speech and voice Printing abilities

STAGES OF HUMAN-MACHINE INTERACTIONS

There are 4 stages of HMI. This involves the activities of intention, selection, execution and evaluation.
Intention: This is the first stage of HMI. In this stage the user first sets the goal for interaction. And
then perform actions using a system to reach to the goal. This is a mental stage.

Selection: This stage is also defined as the selection of action. In this stage order of actions are set.
This means that the user defines how the interaction is going to take place.
Execution: Once the course of action is set it moves for the execution. In this stage the action is
performed.

Evaluation: This is very important stage in HMI as the success of the interaction depends upon the
feedback.
We can understand these stages in simple terms through an example of celebration of a birthday
party. Neha has an intent to celebrate her birthday party. She decides to celebrate it in a hotel.
This stage is called intention. She selects a hotel and decides on a few friends and relatives with
whom she would like to share her day. This is the selection stage. Finally, she picks up her
friends and relatives in a car and drives to reach the hotel. She orders her meal. This is called the
execution stage. Could she celebrate her birthday? Were her friends happy? Did the meal served
to them reached their level of expectation? Asking and answering these questions are termed
as evaluation.

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