A sign on the shop says Sale. A person reads it. The shop speaks; the reader listens. That’s communication. It is one-way. The person opens the shop door and walks in. That becomes interaction.

Interaction goes further. It links actors through reciprocal action. You press a button. The system responds. You swipe. The screen scrolls. Both sides act. Both sides change. Even if one is a person, the other a system. Interaction includes communication, but it demands feedback. But not all communication is interactive. You read a label. You overhear a conversation. You see a blinking cursor. The system speaks, but you remain still. No feedback loop, no interaction. Communication moves information. Interaction moves effect. Communication shapes what we understand. Interaction shapes what we do.

Before we dive deeper into interaction, we need to understand how communication works. One foundational model is the Shannon–Weaver Model (1949), designed for electrical engineering but now applied across human and digital communication.

The Shannon–Weaver Model of Communication

Developed to understand signal transmission in electrical systems, this model has since been applied to many kinds of human communication.

1. Source 🡒 Originator of the message
2. Transmitter 🡒 Converts the message into a signal
3. Channel 🡒 Medium through which the signal travels
4. Receiver 🡒 Converts the signal back into a message
5. Destination 🡒 The intended recipient

Noise is any interference that distorts the message, and identified through three levels:

1. Technical – Is the signal clear?
2. Semantic – Is the meaning understood?
3. Effectiveness – Did it produce the desired response?

Please note, the desired response doesn't necessarily mean feedback, coherence is a response too.

This model is linear. But for interaction, we'll have to create a loop. If your retina catches light or your ears detect sound, that is not interaction. Interaction requires:

1. Intention
2. Action
3. Response
4. Change

Communication, even when structured, leaves room for interpretation. Interaction needs to take this into account. While communication transmits meaning; interaction, by contrast, produces change through exchange. It introduces mutual feedback. Let's revisit the example: you walk past a shop sign and read it without effort. The sign sends a signal, your perceptual system receives and decodes it, and you may even grasp its meaning. But unless this results in a change in your internal state or leads to a new goal, interaction hasn’t occurred. Interaction is rooted in goal-directed behavior — a cycle of intention → action → perception → evaluation. If this loop isn’t completed, if there’s no reciprocal influence between system and agent, then there’s communication, but no interaction.

Passive reception of information ≠ interaction.

Interaction is behavior in time. If we were to classify every instance of perception or signal processing as interaction, we would fall into absurdity. Then, whatever happens in the universe is an interaction. But that can’t be true, because interaction implies at least some form of connection, mutual influence, and closed feedback, however minimal.

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